Ralph M. Trüeb1
(1)
Center for Dermatology and Hair Diseases, Wallisellen, Switzerland
Abstract
Hair care, color, and style play an important role in people’s physical appearance and self-perception. Hair defines an individual’s gender, age, sexual attitude, and social status. There are no significant differences in the number of hair follicles between men and women, or between different races. Differences in the appearance of hair are due to the type of hair produced by a follicle and to the type of hair care and cosmetics practiced by the individual.
Ah, such are the lures of the toilet
that none will for long hold aloof from them.
Cosmetics are not going to be a mere
prosaic remedy for age and plainess
but all ladies and all young girls
will come to love them.
Max Beerbohm, A Defence of Cosmetics (1894)
Hair care, color, and style play an important role in people’s physical appearance and self-perception. Hair defines an individual’s gender, age, sexual attitude, and social status. There are no significant differences in the number of hair follicles between men and women, or between different races. Differences in the appearance of hair are due to the type of hair produced by a follicle and to the type of hair care and cosmetics practiced by the individual.
Healthy hair is usually perceived to be shiny hair with a smooth texture and clean-cut end or tapered tips. Hair texture and shine relate to hair surface properties, while the integrity of hair ends relates to the hair cortex.
Hair consists of an outer hydrophobic lipid epicuticle, a layer of flattened overlapping cuticle cells surrounding the elongated polyhedral cortical cells. The cortical cells surround an optional and often discontinuous central medulla. The surface of the hair is covered in a covalently bound, monomolecular layer of a unique, branched fatty acid, 18-methyl eicosanoic acid, or the f-layer. The intact cuticle has a smooth appearance, allowing light reflection and limiting friction between the hair shafts. It is responsible for the luster and smoothness of hair. Finally, the cortex consists of closely packed spindle-shaped cortical cells filled with keratin filaments that are oriented parallel to the longitudinal axis of the hair shaft and an amorphous matrix of high-sulfur proteins. The keratin chains have a large number of sulfur-containing cysteine residues, which form covalent disulfide bonds in adjacent keratin filaments. The disulfide bonds contribute to the shape, stability, and texture of the hair.
The condition of the hair fiber is dependent on hereditary and ethnic factors, age and sex, nutritional and overall health status, condition of the scalp, hair length, hair care and styling habits, and external factors and hair damage including those from cosmetic hair treatments.
Manipulation of the normal hair structure is dictated by culture, and although cosmetic procedures are inherently aimed to be safe, there remains a potential for damage to the hair shaft.
For permanent changes to the color or style of hair, the chemical reaction of coloring, perming, or straightening must occur in the cortex. The f-layer is removed from the surface with any chemical procedure, and the internal disulfide bonds of the cortex are broken in hairstyling and permanent waves.
Loss of luster, frizz, split ends, and other hair problems are particularly prevalent among women who repeatedly alter the natural state of their hair.
While medicinal treatments of hair aim at specific problems relating to the superficial condition of the scalp, such as dandruff, itchiness, and hair loss, cosmetic hair treatments aim at cleansing the hair, conditioning hair, styling hair, changing hair color, and perming hair. Table 6.1 lists the main types of hair cosmetics.
Table 6.1
Hair cosmetics
|
Hair shampoos: to remove sebum and environmental dirt without decreasing cosmetic appearance of hair |
|
Hair conditioners: to improve hair manageability, decrease hair static electricity, add luster, and enhance styling ease |
|
Hairstyling aids: to maintain hair in fashionable arrangement while improving the quality of hair fibers |
|
Hair dyes: to lighten or darken hair color while covering gray hair |
|
Permanent hair waving/straightening: to reposition hair keratin disulfide bonds in a new curly or straight position |
A survey performed by Procter & Gamble demonstrated that 70 % of women are not satisfied with the condition of their hair at least once a week and 40 % are unsatisfied with their hair care products. This has to do with the fact that approximately half of women are incapable of determining their hair type correctly and choosing the appropriate hair care and styling products.
∎
Women are very well aware of how their hair should ideally look, but are not knowledgeable about the appropriate hair care and cosmetic products.
These study findings underscore the significance of counselling on appropriate hair care and cosmetics besides prescribing effective treatment of hair loss.
According to a study, directed by Marianne LaFrance, Professor of Psychology and Professor of Women’s and Gender Studies at Yale University, bad hair days affect individual’s self-esteem increasing self-doubt, intensifying social insecurities, and becoming more self critical in general.
∎
Bad hair is hair that sticks out; needs cutting; is frizzy, damaged, poofy, flyaway, wild, and badly cut; or is bushy and greasy.
Good hair is manageable, smooth, and stylish, shines, has volume, and is bouncy.
This chapter aims to help the clinician to understand the role of various biological processes and pathologic conditions, hair care habits and procedures, and environmental factors on hair health.
6.1 Hair Weathering
Hair weathering is the progressive hair damage resulting from external factors, basically the wear and tear from environment and cosmetic procedures that mainly affect the free end of the growing hair fiber: friction damage from combing and brushing; damage from excessive heat blown or from curling irons; structural and chemical damage from chemical treatment of hair, that is, bleaching, coloring, perming, and straightening; and finally effects of ultraviolet radiation or photoaging.
Hair is porous, and damaged hair is increasingly so. Water absorption causes hair shaft swelling. Wet hair has higher combing friction than dry hair; therefore, combing wet hair is more likely to stretch brittle hair to the point of breaking. When wet, hair can be stretched by 30 % of its original length without damage. Irreversible changes occur when hair is stretched between 30 and 70 %; ultimately, stretching to 80 % causes fracturing.
Although all hair exhibits some degree of weathering, longer hair, subjected to repeated insults, inevitably shows more severe changes of weathering.
Negroid hair has a larger diameter, lower water content, and flattened elliptical cross section. It is usually black or dark brown, tightly curled, low in shine, and high in sebum. It has increased grooming friction, which combined with low tensile strength makes it more difficult to manage.
Finally, hair may be intrinsically weak in the less common inherited abnormalities in hair fiber formation. We described acquired hair fragility in two women with pili annulati with a causal relationship with androgenetic alopecia. Pili annulati are defined by characteristic alternating light and dark banding in the hair shaft, due to air-filled spaces between the macrofibrillar units of the hair cortex, and are regarded as a congenital hair shaft disorder without increased hair fragility. In the presented cases of pili annulati, fragility of hair developed in a causal relationship with the onset of androgenetic alopecia. Accordingly, trichorrhexis-nodosa-like hair fracturing was exclusively limited to the androgenetic region. In general, secondary trichorrhexis nodosa is an unspecific finding related to excess stress of hair in relation to its fragility. With onset of hair thinning due to androgenetic alopecia, progressive reduction of hair shaft diameter may cause increased fragility in pili annulati. In this case, hair shaft fracturing occurs within the area of androgenetic alopecia and colocalizes with the air-filled cavities of pili annulati.
Features of weathering include damaged cuticles (Fig. 6.1a), longitudinal fissures or split ends (trichoptilosis, Fig. 6.1b), and transverse fissures (trichorrhexis nodosa, Fig. 6.1c). These result from alterations in the ultrastructure, physical, and chemical properties of the hair fiber, that is, mechanical abrasion of the cuticle, damage of the hair cortex with alterations of viscoelastic properties and tensile strength of the hair fiber, and depletion of specific amino acids: methionine (by minus 50 %), tryptophane (−50 %), cystine (−20 %), histidine (−20 %), tyrosine (−15 %), and lysine (−10 %).
Fig. 6.1
(a–c) Hair weathering. (a) Damaged cuticles. (b) Split ends (trichoptilosis). (c) Transverse breakage (trichorrhexis nodosa)
∎
Hair care products that improve the structural integrity of damaged hair fibers and increase tensile strength are available, as are products that increase hair volume, reduce frizz, and improve overall hair manageability.
6.2 Shampoos
Shampoo treatments are the most commonly used means of managing hair and scalp conditions. Until the introduction of the first non-alkaline shampoos in 1933, soap was the only available cleanser for the hair. Today, shampoos are expected to be more than mere cleansing agents. They are expected to not dry out the hair; to produce lather in hard and soft water and when applied to oily hair; to be nonirritating to skin and mucous membranes; to be chemically and physically stable; to possess conditioning benefits; to be biodegradable; and affordable. A shampoo is expected to improve the hair cosmetically while being tailored to the needs of various hair types as well as age and individual habits. Scalp condition is another important factor in individual health and well-being; the scalp should neither be oily nor should dandruff develop.
Shampoos have evolved into high-tech products consisting of 10–30 ingredients that are combined in precise formulations to meet consumer demands (Fig. 6.2, Table 6.2).
Fig. 6.2
Shampoo ingredients
Table 6.2
Shampoo ingredients and effects on hair and scalp condition
|
Shampoo ingredients include: |
|
Detergents, that is, surfactants |
|
Conditioning and active ingredients for hair manageability |
|
Additives that |
|
Modify the surfactant effect (viscosity control agents, foam stabilizers) |
|
Stabilize the product (preservatives) |
|
Increase its appeal (fragrances, dyes, ingredients for consistency, and pearlescent appearance) |
|
The most important effects of shampoo on the hair are: |
|
Moisturizing |
|
Adsorption and/or penetration of the hair |
|
Cleansing, removal of oils, lipid regeneration |
|
The following effects of shampoo influence scalp condition: |
|
Restoration of alkali neutralization ability (pH) |
|
Dryness |
|
Seborrhea |
|
Scalp microbial flora (Malassezia spp., Propionibacterium spp.) |
|
Enzyme activity of the scalp |
|
Scalp circulation |
6.2.1 Shampoo Surfactants
The cleansing ability of a shampoo depends on the surface activity of its detergents. Surface-active ingredients, or surfactants, facilitate the removal of environmental dirt by reducing surface tension between water and dirt; dirt is suspended in the water phase and adsorption prevented. This is achieved by a special molecular structure consisting of a hydrophilic and a lipophilic group. Sebum and dirt are bound and surrounded at the center of a micelle structure with the hydrophilic molecule ends pointing outward. Dirt particles become water soluble and can be removed from the hair shaft.
∎
Surfactants are classified according to hydrophilic polar group as anionic, cationic, amphoteric (zwitterionic), and nonionic.
The cleansing ability of a shampoo depends on how well it removes grease as well as the type and amount of surfactants used. Various surfactants are used in shampoos in order to accommodate different hair types. In most products, the shampoo base consists of anionic and amphoteric surfactants. Depending on individual product requirements, nonionic and cationic surfactants are added to modify the effects of the surfactants or as conditioning agents for hair with surface damage.
Anionic surfactants are characterized by a negatively charged hydrophilic polar group. Well into the twentieth century, natural soaps were the most commonly used anionic hair-cleansing substances. Soap consists of salts that are extracted from naturally occurring animal or vegetable fatty acids. Synthetic surfactants have now replaced soap as a hair cleanser. Because soap is sensitive to hard water, it leaves insoluble salts on the hair, forming a film which causes a dull look. Soap’s alkaline pH can make it irritating to the skin and mucous membranes. The first shampoos introduced on the market in 1933 were alkyl sulfate surfactants. These were still sensitive to hard water and were not adequately tolerated by the skin. They have since been replaced by sodium alkyl ether sulfates which are now the leading surfactants. These are superior with regard to sensitivity to water hardness as well as skin and mucous membrane tolerability and are virtually the only surfactants that can also be used alone in a shampoo as raw ingredients. The best-known anionic surfactants are sulfated fatty alcohols, alkyl sulfates, and their polyethoxylated analogues, alkyl ether sulfates. They possess an outstanding cleansing ability and produce rich lather. A number of anionic surfactants, such as alkyl ether carboxylate, acyl peptides, alkyl sulfosuccinate, and olefin sulfonate, are well tolerated by the skin and are used together with other anionic and amphoteric surfactants to optimize shampoo properties.
Amphoteric (zwitterionic) surfactants contain both negatively and positively charged hydrophilic polar groups. At low pH values, they behave as cationic agents and at higher pH values as anionic agents, and are thus classified between cationic and anionic surfactants. Amphoteric surfactants form complexes with anionic surfactants and reduce their tendency to attach to proteins. In combination with anionic surfactants, amphoteric surfactants are mainly used to optimize anionic-based shampoos: amphoteric acetates/diacetates in particular demonstrate excellent skin and mucous membrane tolerability, have a conditioning benefit on the hair, and are suitable for use in mild shampoos. Examples include betaine, sulfonate betaine, and amphoteric acetate/diacetate.
Nonionic surfactants differ from other surfactants in that they do not possess a charged polar group and are hence compatible with all other surfactants. They are also among the mildest form of surfactant; they make good cleansers with dispersion and emulsification properties, but lather poorly. In combination with alkyl ether sulfates or amphoteric surfactants, they serve to enhance tolerability in very mild cleansers such as baby shampoos. Examples of nonionic surfactants are fatty alcohol ethoxylates, sorbitan ether esters, and alkyl polyglucosides.
Cationic surfactants are quaternary ammonium compounds which are characterized by a positively charged hydrophilic polar group. Given its amino acid structure, the keratin found in human hair has an excess of negatively charged acid groups. The positively charged quaternary ammonium compounds of cationic surfactants thus attach by salt bonds to the negatively charged hair and remain after rinsing. Due to its high level of cysteine, damaged hair contains a higher number of negatively charged acid groups and thus absorbs more quaternary ammonium compounds than intact hair. Because of this quality, quaternary ammonium compounds are used as conditioning agents for damaged hair. Although they make hair easier to comb and manage, and they have antistatic properties, they are poor cleansers and do not lather well. They are also potentially strong irritants and are thus only used with less irritating nonionic surfactants in shampoos designed for chemically treated or very dry hair. Their incompatibility with anionic surfactants limits their use in other shampoo formulations.
Table 6.3 lists the surfactant types according to their polar group charge, chemical classes and examples, their characteristics, and purposes in a shampoo formulation.
Table 6.3
Shampoo surfactants
|
Surfactant type (polar group charge) |
Chemical class/examples |
Characteristics |
Purpose |
|
Anionics (negative) |
Lauryl sulfates, laureth sulfates, sarcosines, sulfosuccinates |
Deep cleansing, may leave hair harsh |
Cleansing |
|
Cationics (positive) |
Long-chain amino esters, ammonioesters |
Poor cleansing, poor lather, impart softness and manageability |
Conditioning |
|
Amphoterics (both) |
Betaines, sultaines, imidazolinium derivatives |
Nonirritating to eyes, mild cleansing, impart manageability |
Additive for modification of surfactant activity |
|
Nonionics (none) |
Polyoxyethylene fatty alcohols, polyoxyethylene sorbitol esters, alkanolamides |
Mildest cleansing, impart manageability |
Cleansing |
6.2.2 Shampoo Additives
Shampoo products are also expected to possess stability and to have an appealing quality, making the use of a number of additives necessary.
In addition to selection and combination of surfactants, additives also help reduce skin irritation. Moisturizers and humectants are added to make the hair silkier:
· Moisturizers include natural oils, fatty acid esters, and alkanolamides.
· Humectants include propylene glycol, polyethylene glycol, glycerin, sorbitol, and lactate.
Ensuring shampoo stability requires:
· Use of preservatives to protect against bacterial contamination: organic acids and their derivatives, for example, parahydroxybenzoic acid ester, salicylic and sorbic acid, methylparaben, and formaldehyde releasers, for example, DMDM hydantoin
· UV absorbers to stabilize dyes against light: benzophenone derivatives
· Antioxidants to protect oxidation-sensitive substances: ascorbic acid, α-tocopherol, butyl hydroxyanisole
· Buffers to ensure pH stability: citrate, lactate, and phosphate buffers
· Cosolvents to keep conditioning oils and fragrances clear in solution
· Dispersing agents to keep otherwise insoluble agents, such as silicone oils and antidandruff agents, in suspension: polyvinylpyrrolidone
Last, but not least, attractiveness of a shampoo is enhanced by fragrances, dyes, and special ingredients that give it a pearlescent appearance:
· Fragrance oils cover up the typically fatty odor of the shampoo base and lend the product and individual, pleasant-smelling scent. An appealing fragrance also helps promote regular use of the product.
· Dyes and liquid crystal concentrates give the shampoo a pearlescent and more concentrated appearance. Liquid crystal concentrates also contribute to its moisturizing effect. They usually consist of insoluble crystal particles made up of fatty acid esters of polyols and alkanolamide derivatives of fatty acids that reflect light.
6.2.3 Shampoo-Conditioning Agents
Depending on hair length and exogenous factors, the distal end of the continually growing hair shaft exhibits increasing signs of damage (hair weathering).
∎
The aim of conditioning agents in a shampoo is to maintain the natural condition of newly grown hairs for as long as possible.
Virtually all standard shampoos used today contain conditioning agents. Damaged hair can, of course, not be restored to the condition of healthy, newly growing hair, and more than a reparative effect cannot be expected. Nonetheless, it is possible to increase shine and make hair more manageable and easier to comb by using a shampoo with a high proportion of conditioning agents, that is, the conditioner effect.
Conditioning agents include fatty substances such as vegetable oils, wax, lecithin and lanolin derivatives, protein hydrolysates (collagen, silk, animal proteins), quaternary ammonium compound, and silicones.
There is increasing use of cationic polymers in place of monomer quaternary ammonium compounds, in which the cationic groups are integrated in a polymer structure, for example, polyquaternium-10 and polyquaternium-16 as well as guar hydroxypropyltrimonium chloride. These adhere more firmly to the hair than monomer bonds and leave a film that coats the surface of the hair fiber, making it appear to be soft and smooth while improving shine and color by altering the refractive index. In addition to their use in conditioners, these cationic polymer-finishing agents have become a main component of 2-in-1 shampoos which combine cleansing and conditioning actions. The amount used must correspond to the condition of the hair since these agents have a high affinity for the hair and with repeated use can build up on the hair shaft. Excessive conditioning can make hair less manageable and appear oily.
In addition to cationic polymer-finishing agents, silicones are also used, especially dimethicone, which is added along with special dispersing agents to a shampoo base containing a relatively high proportion of surfactants. The strong conditioning effect occurs as a result of extremely fine dimethicone droplets being deposited on the hair as the shampoo is diluted during washing.
∎
Silicones have a similar effect to that of fats and oils, but without weighing the hair down. Silicones add lubricity and reduce friction that arises from combing, making the hair easier to comb and style, and thus also preventing damage. They also give the hair antistatic properties that prevent it from becoming frizzy.
Table 6.4 lists the hair conditioner categories with their primary ingredients, main advantages, and hair-grooming benefits.
Table 6.4
Hair-conditioning agents
|
Hair conditioner category |
Primary ingredient |
Main advantage |
Hair-grooming benefit |
|
Fatty ingredients |
Fatty alcohols, lanolin derivatives, oils, waxes, lecithins |
Increase hair shine, increase hair manageability |
Improve appearance of dry hair |
|
Cationic detergents and film formers |
Quaternary ammonium compounds (quats) |
Smooth cuticle, decrease static electricity |
Excellent to restore damaged, chemically processed hair |
|
Polymers (polyquaternium) |
Fill hair shaft defects, decrease static electricity, improve shine |
Improve appearance of dry hair, improve grooming of coarse, kinky hair |
|
|
Protein-containing |
Hydrolyzed proteins (keratin, collagen, silk, wheat, soya) |
Penetrate hair shaft to minimally increase strength |
Temporarily mend splits |
|
Silicones |
Dimethicone, cyclomethicone, amodimethicone |
Thin coating placed on hair shaft |
Decrease static electricity, decrease combing friction, add shine |
6.2.4 Shampoo Active Ingredients
Active ingredients are added to shampoos for the management of specific problems affecting the scalp such as mild dandruff, seborrhea, seborrheic dermatitis, and psoriasis. The spectrum of active shampoo ingredients is broad and varied, from clinically proven, primarily antidandruff agents to traditionally used substances derived from natural sources, for example, plant extracts (Table 6.5).
Table 6.5
Plant extracts (selection) for hair and scalp care
|
Plant |
Botanical |
Indication |
|
Soapbark |
Quillaja saponaria |
Cleansing |
|
Antimicrobial |
||
|
Willow bark |
Salix alba |
Dandruff |
|
Repellent against head lice |
||
|
Coltsfoot |
Tussilago farfara |
Dandruff |
|
Seaweed |
Fucus vesiculosus |
Seborrhea |
|
Thyme |
Thymus vulgaris |
Seborrhea |
|
Rosemary |
Rosmarinus officinalis |
Promotes blood circulation |
|
Mallow |
Malva sylvestris |
Conditioning (thin hair) |
|
Linden |
Tilia cordata |
Conditioning (thin hair) |
|
Millet |
Panicum miliaceum |
Conditioning (thin hair) |
|
Horsetail |
Equisetum arvense |
Conditioning (dry, brittle hair) |
|
Avocado |
Persea gratissima |
Conditioning (colored hair) |
|
Sage |
Salvia officinalis |
Conditioning (gray hair) |
|
Chamomile |
Matricaria chamomilla |
Scalp irritation |
|
Heartseed |
Cardiospermum halicacabum |
Scalp irritation |
|
Witch hazel |
Hamamelis virginiana |
Scalp irritation |
|
Aloe vera |
Aloe barbadensis |
Scalp irritation |
|
He Shou Wu |
Polygonum multiflorum |
Antiaging |
Antidandruff agents. A study with 1,000 men reported that 18 % of respondents had mild dandruff and 4.5 % severe dandruff. In a smaller study with 500 students, 70 % reported having dandruff.
∎
The specific anatomic features of the scalp skin, such as the large number of terminal hair follicles and the enlarged epidermal surface due to numerous hair canals, contribute to a higher rate of exfoliation. Even a healthy scalp will develop dandruff within 1 or 2 weeks if the hair is not washed.
Pathological dandruff results from accelerated proliferation of epidermal cells and thus increased exfoliation of variously large collections of abnormally keratinizing epidermal cells. This leads to breakdown of the normal columnar structure of the stratum corneum and increased formation of cell aggregates which determine the size of the flakes. The process results from focal inflammation of the scalp with parakeratosis which causes abnormal exfoliation and an altered light refractive index of the keratinized cell aggregates (Fig. 6.3). The clinical appearance of dandruff is determined by the size, adherence, and light refractive characteristics of the flakes. Among the factors that lead to inflamed patches on the scalp are physical/chemical stimuli, microbial colonization, and sebum production and composition.
Fig. 6.3
Pathogenesis of dandruff (From Trüeb 2007)
The lipophilic yeast Malassezia spp. normally inhabits the scalp, making up about 45 % of its resident microflora. In patients with dandruff, it is the predominant yeast type with about 75 % and in patients with seborrheic eczema 83 %. Modern classification and nomenclature of Malassezia spp. is based on DNA typing. The most common types found on the scalp are M. restricta and M. globosa, the latter of which in particular has a major role in the development of dandruff given its high level of lipase activity.
Dandruff is divided by clinical appearance into the following types:
· Simple dandruff (Fig. 6.4a) typically occurs with dry skin as a result of atopic dermatitis or age-related dry skin. It can be caused by excessive hair cleansing or the use of a shampoo designed for oily hair. Typical findings include dry, bran-like scales, and patients often complain of itching. Most authors also cite the coexistence of overgrowth of Malassezia spp. in simple dandruff as evidence of its role in pathogenesis.
Fig. 6.4
(a–c) Dandruff. (a) Simple dandruff (pityriasis simplex). (b) Oily dandruff (pityriasis oleosa). (c) Asbestos-like scaling (pityriasis amiantacea)
· Oily dandruff (Fig. 6.4b) is associated with seborrhea of the scalp. It often occurs with inadequate personal hygiene, and Malassezia spp. is widely believed to be involved in pathogenesis. Firmly adherent, oily, bran-like scales are found, often on the anterior hairline, external ear, preauricular area, and around the eyes.
· Asbestos-like scaling or pityriasis amiantacea (Fig. 6.4c) frequently occurs as an idiopathic disorder in girls, but can also be related to lacking personal hygiene. It presents with well-circumscribed areas of thick, asbestos-like, firmly attached scales with focal hair loss and no itching. Concomitant postauricular skin cracks are typical. Underlying specific dermatological disease such as eczema, psoriasis, tinea capitis, and – rarely – pemphigus foliaceus should be excluded.
∎
Medicated shampoos containing antidandruff ingredients are essential in treating dandruff and exfoliative scalp disorders such as seborrheic eczema and psoriasis. The choice and frequency of shampooing are determined by the underlying cause, that is, dry skin (sebostasis) or seborrhea. Patients with dry skin should be advised to wash their hair less frequently and avoid using oily hair shampoos. For oily dandruff, on the contrary, daily hair cleansing alone can lead to improvement.
Table 6.6 lists active ingredients used in the treatment of dandruff according to their mode of action.
Table 6.6
Antidandruff shampoo ingredients
|
Keratostatic agents that inhibit overproduction of keratinizing cells: coal tar and ammonium bituminosulfonate (pale sulfonated shale oil as a coal tar substitute) |
|
Keratolytic agents that break down cell aggregations: colloidal sulfur and salicylic acid |
|
Antimicrobial agents that inhibit Malassezia yeasts: selenium disulfide, zinc pyrithione, piroctone olamine, ketoconazole, and ciclopirox olamine |
|
Combinations of these |
Zinc pyrithione demonstrates a strong antidandruff effect with a low potential for irritation or sensitization. Clinical studies have shown it to be superior to coal tar, selenium disulfide, and piroctone olamine.
In one study, the effect of 2 % ketoconazole was better and longer-lasting than 1 % zinc pyrithione, but improving shampoo formulation can increase the effectiveness of antidandruff agents. In particular, the effectiveness of zinc pyrithione could be significantly improved with the use of micronized ingredients, especially given the legal maximum of 1 %. The zinc pyrithione molecule is present as a crystalline suspension in glycol distearate and is not water soluble. The formulation allows even distribution of zinc pyrithione crystals in shampoo, and the use of nonspherical crystals measuring only 2.5 μm allows better adsorption and more even distribution on the scalp. This is particularly effective in inhibiting Malassezia yeasts, even with a short contact time and rinsing. The combination of zinc pyrithione with zinc carbonate leads to reduced dissociation of the active ingredients into zinc and pyrithione, which alone have a lower antidandruff effect.
In terms of minimal inhibitory concentrations (MIC) on Malassezia spp., there are considerable differences in potency of the various antidandruff agents (in brackets): crude coal tar (MIC, 250–5,000), salicylic acid (MC, >100), selenium disulfide (MIC, 1.56–3.3), zinc pyrithione (MIC, 0.78–1.66), and ketoconazole (MIC, 0.1). Potency in terms of MICs is important, but it is not the sole factor that determines efficacy. Other influential aspects of treatment pharmacology include delivery, retention, bioavailability, mildness, and esthetics. Finally, dandruff must be controlled through regular treatment.
∎
Patients are compliant for only 30 s. Shampoos that achieve antimycosis on contact lead to more successful management of dandruff. Ultimately, the cosmetic aspects of shampoo-based therapy must be acceptable to patients or compliance will be compromised. Three out of four women suffering from dandruff would prefer to use a medicated shampoo with conditioning benefits.
Ingredients for managing scalp seborrhea. A greasy scalp is a frequent condition, both causing cosmetic embarrassment, and a disposition to pathologic conditions such as seborrheic dermatitis and scalp folliculitis. The condition sets in with adolescence, often with premenstrual exacerbations, and its frequency declines after the age of 30 years, with sebostasis dominating after menopause. Oral antiandrogenic treatment with cyproterone acetate represents to most effective treatment of scalp seborrhea in women.
∎
A significant improvement in seborrhea generally cannot be achieved with over-the-counter shampoos.
Coal tar (Liquor carbonis detergens), which reduces sebum production, is virtually the only effective active ingredient in medicated shampoos. Ammonium bituminosulfonate (ichthammol) is comparatively ineffective. To maintain volume, the surface of the hair must be prevented from becoming too smooth, and to avoid lipolytic or peroxidative transformation of scalp or hair lipids, antimicrobial substances are used. This is usually achieved with a mild, generally anionic surfactant base consisting of effective cleansing substances with low substantivity. Inhibition of microbial lipolysis can also be achieved by the surfactants forming the shampoo base. Antimicrobial agents that are effective against Malassezia spp. are suited for use in seborrhea and dandruff. Selenium disulfide is contraindicated since it increases sebaceous gland excretion. Additional conditioners, especially moisturizers and cationic polymers, should be avoided in hair that has a tendency to become oily, since they weigh it down. The use of plant extracts containing tannin, for example, oak bark (Quercus spp.) extract, can have a positive influence holding a style by roughening the surface of the hair.
Special care ingredients for managing the itchy or burning scalp. Special care ingredients with some degree of efficacy in treating itchiness or burning sensations of the scalp are piroctone olamine (antidandruff agent with antipruritic properties), menthol (antipruritic agent), polidocanol (local anesthetic agent), and plant extracts with anti-inflammatory properties, such as chamomile (Matricaria chamomilla), heartseed (Cardiospermum halicacabum), or witch hazel (Hamamelis virginiana).
Witch hazel is an astringent produced from the leaves and bark of the North American witch hazel shrub, originally used for medicinal purposes by Native Americans, who produced witch hazel extract by boiling the stems of the shrub and producing a decoction, which was used to treat inflammatory conditions. Early Puritan settlers in New England adopted this remedy from the natives. A missionary, Dr. Charles Hawes, eventually learned of the preparation’s therapeutic properties and further determined that the product of the plant’s twigs was even more efficacious. Hawes’ process was further refined by Tomas Newton Dickinson, Sr., who is credited with starting the commercial production of witch hazel extract in 1866 and establishing its wide use. The main constituents of the extract include tannin, gallic acid, catechins, proanthocyanins, flavonoids (kaempferol, quercetin), essential oils (carvacrol, eugenol, hexenol), choline, and saponins. It is a strong antioxidant and astringent, which makes it useful as a natural remedy for acne, psoriasis, eczema, aftershave applications, ingrown nails, and cracked or blistered skin, and for treating insect bites.
∎
In shampoo form, witch hazel is particularly useful in the treatment of the red scalp syndrome and in preventing or soothing scalp irritation resulting from sustained use of ethanolic topical minoxidil solutions. An alternative is to compound minoxidil into a topical solution of hamamelis distillate.
6.2.5 Product Safety
The public is keenly interested in knowing of any health risks potentially associated with everyday products such as shampoo.
∎
The effects of shampoo ingredients such as crude coal tar, halogenated organic compounds, formaldehyde, formaldehyde releasers, and musk on personal health and/or the environment are only a few of the issues that have received recent media attention.
The product safety rating of a shampoo is based on an evaluation of the data for all ingredients with regard to skin and mucous membrane tolerability, sensitization potential, acute and chronic toxicity, mutagenicity, skin penetration and accumulation potential, biodegradability, and aquatic toxicity.
Carcinogenicity. Opponents of tar-based products, concerned with the risk of carcinogenicity, grew even more vocal with the first publications on percutaneous absorption of polycyclic aromatic hydrocarbons (PAH) from tar-based shampoo. In fact, in the roughly 100 years since tar-based products have been used for dermatological indications, the incidence of related skin cancer is very rare and no relationship has been reported with the use of coal tar-based shampoos. Containing up to 79 μg/g benzoapyrene, the main PAH in tar-based shampoos, only a fraction of 79 μg PAH per hair washing is absorbed. By way of comparison, the benzoapyrene in a pound of grilled ground beef is about 10 μg.
Skin and mucous membrane irritation. Critical assessment of validated data on the frequency of contact allergies to shampoo demonstrates their low risk.
Given that shampoos are diluted by water, have a short contact time, and are rinsed off, the risk of sensitization is low.
Nevertheless, in patients who are already sensitized, exposure could conceivably trigger eczema. Patients should therefore be advised of all ingredients contained in the shampoo; a complete allergy history can also help avoid contact with relevant allergens. Although in most cases testing individual ingredients is sufficient, testing the final formulation for skin and mucous membrane irritation is preferable. Such testing is not mandated by current directives on cosmetic products and is often not performed. Therefore, safety ratings of cosmetic shampoos used for therapeutic indications should be critically assessed on an individual patient basis.
Environmental safety. Environmental safety requirements for cosmetic products are derived from applicable environmental laws. Water protection regulations mainly address the effects of substances that end up in the water; for a given ingredient to be approved for use, it should not be expected to cause irreversible damage. Rapid and complete biodegradation of surfactants, which are used in large quantities, is required and has been the subject of careful scrutiny and confirmation.
Most knowledge of ecological characteristics of surfactants has come from their use in laundry detergents and cleaners, which are used in far larger quantities, rather than from the comparatively smaller amounts used in shampoos which pose less of a threat to the environment.
6.2.6 Methods for Measuring Efficacy of Hair Care Products
Modern hair care products must be safe and nonirritating, but they must also demonstrate efficacy. Cosmetics laboratories have developed objective methods for measuring efficacy. Measurements are made using individual hair fibers as well as strands of hair. Compared to measurements of individual hair fibers, those conducted on groups of hairs are more valuable, yet the degree of abstraction remains high given that consumers are not concerned with strands of hair, but with overall appearance. Nevertheless, they supply important information. Measurement methods encompass a large number of computerized and sometimes robot methods which are used to quantify cosmetic phenomena and effects such as buildup, bounce, body, manageability, entanglement, causes of damage, and conditioning benefits. By using a carefully selected variety of methods, refining the method park, and conducting dialogues with experts on subjective tests with end consumers, hair care effects can be precisely described and optimized to suit practical considerations and economic targets. Testing of various hair types in climate chambers with different levels of humidity is aimed at developing global hair care product lines.
6.3 Conditioners
Sebum is the ideal hair conditioner. Excessive removal of sebum in the course of washing the hair and scalp created the need for synthetic sebum-like substances that attempt to supply hair with the positive attributes of sebum while avoiding the greasy appearance of excessive sebum and dirty hair.
Hair conditioners aim at:
· Imparting softness
· Increasing luster and gloss
· Reducing flyaway
· Enhancing disentangling facility
· Alleviating defects related to certain types of hair and hair treatments
They are available as shampoos for dry or damaged hair, conditioning (2-in-1) shampoos, and hair conditioners (liquids, creams, pastes, gels). The hair conditioning agents are basically the same used in conditioning shampoos and listed in Table 6.4.
6.4 Hairstyling Aids
Hairstyling aids are intended to maintain hair in fashionable arrangement while improving the quality of hair fibers. Hairstyles are in part dictated by the available technology in hairstyling products.
Hairstyling aids aim at:
· Maintaining hair in desired position
· Adding increased hold to hair
· Creating illusion of fullness
· Creating a wet, spiky look
· Straightening, conditioning, moisturizing, and adding shine to kinky hair
They are available as hair spray, hairstyling gel, hair-sculpturing gel, hair wax, hair mousse, and ethnic styling aids, such as pomade, brilliantine, oil sheen spray, and curl activator.
Table 6.7 lists available styling products, their formulation, aim, and application.
Table 6.7
Hairstyling aids
|
Styling product |
Formulation |
Aim |
Application |
|
Hair spray |
Aerosolized spray polymer (PVP, VA, MEA) |
Maintain hair in desired position |
Sprayed on finished hairstyle |
|
Hairstyling gel, hair-sculpturing gel |
Clear gel polymer |
Hold hair away from scalp for fullness or spiky look |
Rubbed with hands on towel-dried hair |
|
Hair wax |
Soft opaque formable wax |
Add increased hold to hair |
Massaged into dry hair after softening in palm |
|
Hair mousse |
Aerosolized polymer foam |
Hold hair away from scalp for fullness or spiky look |
Squirted onto hand and dabbed through towel-dried hair |
|
Ethnic styling aids: |
|||
|
Pomade |
Ointment of petrolatum |
Straighten, condition, moisturize, add shine to kinky hair |
Combed with hands through hair |
|
Brilliantine |
Liquid oil |
Allow ease of styling and proved shine |
Massaged with hands through hair |
|
Oil sheen sray |
Aerosolized oil |
For shine and moisturization |
Sprayed onto hair |
|
Curl activator |
Clear glycerin gel |
For ringlet hairstyles |
Massaged with hands through hair |
From Draelos (2005)
6.5 Hair Dyes
In the absence of another way to reliably reverse hair graying, hair colorants have remained the mainstay of recovering lost hair color, reaching back as far as to the ancient Egyptians who colored their hair with henna and indigo, and the ancient Romans who used lead combs dipped into vinegar. Henna, obtained from the plant Lawsonia alba, is a naturally occurring hair colorant still frequently used today. Although the color can add red highlights to hair, occasionally on gray hair, it may come out looking orange.
There are several choices open to cover gray hair:
· To apply blond streaks to some of the hair, a procedure called highlighting
· To color only the gray, especially in the beginning when the gray in men affects only the temples or the perimeter in women
· To color about half the hair by wrapping it with a lighter shade producing a natural look
· To color the entire head of hair, usually going two shades lighter than a person’s natural color to prevent a harsh look
The following major types of synthetic hair colorants are currently used:
· Temporary (textile dyes)
· Natural coloring (henna)
· Semipermanent (low molecular weight direct dyes)
· Permanent (aromatic amines)
Temporary hair colorants consist of large complex organic structures that do not penetrate the cuticle. The colors are not intense but are capable of covering gray hair in a subtle way. This may be a good way for an individual to experiment with the coloring idea. The colorant washes out with the next shampoo.
Semipermanent colorants consist of small molecules that penetrate the cuticle. These compounds color gray hair very nicely, are easily applied in a lotion or foam at home, and last for six to ten shampoos.
Permanent hair dye is the most frequently used hair colorant. In permanent hair coloring, the formation of colored molecules from their precursors occurs inside the hair fibers as a result of oxidation by hydrogen peroxide. The most prominent among permanent hair coloring agents are p-phenylenediamine (PPD) and p-toluylendiamine (PTD). The advantage of permanent color is that the color withstands normal hair washing. Because new growth comes out, the roots need to be touched up. Such products are used in a very gratifying manner and safely by millions of individuals worldwide. Besides a cosmetic benefit, hair dyes have been shown to also have a photoprotective effect on the hair fiber.
∎
There have been studies that raised the possibility that long-term usage of permanent hair dyes (particularly black dyes) may be associated with an increased risk of developing certain cancers. However, taken together, the evidence is insufficient to state with certainty whether there is a link between using hair dye and cancer.
More important is contact allergy to PPD and PTD (Fig. 6.5a–c), resulting in allergic contact dermatitis and acute diffuse telogen effluvium following allergic contact dermatitis of the scalp by approximately 3 months.
Fig. 6.5
(a–c) Contact allergy to PPD. (a) Allergic contact dermatitis. (b). Patch testing. (c) Positive patch test
6.6 Cosmetic Treatment for Aging Hair
As hair ages, changes affecting pigmentation and growth become evident. Aging hair is characterized by loss of follicle rigor, consistent with slowing of other body activities with age. Senescence of the hair is particularly visible and consists in failure to pigment the hair shaft (graying), decrease in rapidity of hair growth, and reduction in the diameter of the hair shaft. Senescent alopecia is different from androgenetic alopecia.
Preventive measures begin with early avoidance of factors that cause damage to the hair and scalp such as UV rays, tobacco smoking, poor diet, and stress. UV rays contribute significantly to the aging of the skin and presumably the hair as well.
Cosmetic treatment for aging hair consists in:
· Grooming rules for maintaining good-looking hair (Table 6.8)
· Special shampoo selection for aging hair (Table 6.9)
· Conditioner use
· Use of hairstyling aids
· Hair photoprotection
Table 6.8
Grooming rules for maintaining good-looking hair
|
Manipulate hair as little as possible |
|
Comb hair gently |
|
Avoid combing wet hair |
|
Avoid high temperature appliances |
|
Select a vented ball tip styling brush |
|
Avoid scratching of hair and scalp |
|
Cut away split ends |
|
Preferably wear short hair style (length of hair should be inverse proportional to age) |
From Draelos (2010)
The effect of UV radiation on the hair follicles is attributed, among other things to the light activation of porphyrins produced by Propionibacterium spp. in the hair canal which triggers a follicular microinflammation. For this reason, the use of an antimicrobial solution has been recommended as one possible preventive measure. Another would be photoprotection of the hair and scalp. Cinnamidopropyltrimonium chloride is a quaternized UV absorber that also has a conditioning effect in shampoo. Solid nanoparticles as carriers of UV blockers are in development for use in hair.
The efficacy of hair growth agents or antiaging substances in shampoo is questionable given their dilution with water and short contact time, unless they can be absorbed in effective quantities. Antioxidants and UV absorbers primarily serve to protect oxidation-sensitive oils or dyes against the effects of light. Yet, they are often present in concentrations that are too low to protect the hair. Pantothenic acid is a strong humectant and is therefore considered a conditioner. Finally, topical melatonin has been found to suppress UV-induced erythema and UV-induced reactive oxygen species in a dose-dependent manner.
Table 6.9
Special shampoo selection for aging hair
|
Primary cleanser: |
|
Anionic, usually a lauryl sulfate, in combination with a laureth sulfate, or |
|
A sarcosine for dry hair, resp. |
|
A sulfosuccinate for greasy hair |
|
Secondary cleanser (for mild shampoos): |
|
Nonionic or amphoteric (in baby shampoos) |
|
Shampoo conditioners: |
|
Mature individuals should select conditioners developed for fine hair, preferably: |
|
Silicone (dimethicone) |
|
Panthenol (humectant) |
|
Hydrolyzed proteins (no buildup) |
|
Special antiaging ingredients: |
|
Photoprotective agents |
|
Antioxidants (primarily aims at protecting shampoos from oxidation) |
|
Melatonin |
|
Energizers (caffeine, guarana, gingko)? |
|
Others from TCM (He Shou Wu) or Ayurveda (at least of important commercial interest)? |
6.7 Adverse Effects of Cosmetic Hair Treatments
Besides hair weathering, there exist a number of peculiar adverse effects resulting from inappropriate cosmetic hair treatments. These are:
· Hair matting (from inappropriate hair washing)
· Bubble hair (from inappropriate hair drying)
· Cosmetic hair beads (from inappropriate hairstyling)
· Central centrifugal cicatricial alopecia (from inappropriate hair-straightening procedures)
Women often blame shampoos for their hair loss. Diffuse hair loss due to an inhibition of mitosis associated with long-term use of shampoos containing keratostatic antidandruff agents, such as selenium sulfide, has been discussed in the older literature and remains controversial. More frequently, the impression of increased hair shedding is created through the detachment of scales containing groups of trapped telogen hairs (Fig. 6.6).
Fig. 6.6
Detached scales containing groups of trapped telogen hairs
∎
Absence of effects of dimethicone- and non-dimethicone-containing shampoos on hair loss rates has systematically been demonstrated.
6.7.1 Hair Matting
Hair matting or acute felting of the hair represents a rare condition of irreversible tangling of scalp hair with dramatic onset. It is not a primary hair disorder: physical conditions, chemical agents, and behavioral factors play the main roles. There is invariably a history of previous chemical hair treatment.
Damaged hair, for example, permanently waved hair, is particularly prone to sudden entanglement, which can occur with the use of viscous fluids such as undiluted shampoo. The piling of long hair on the top of the head while shampooing and the repeated friction of wet hair facilitate the process of matting. The raised cuticle cells of the damaged hair interlock as a result of excessive friction and static electricity, and the hair become tangled. Accordingly, microscopy reveals twisting and bending of the hairs through 180°. An irreversible knot, sometimes referred to as a bird’s nest, forms over a limited area (Fig. 6.7a–c).
Fig. 6.7
(a–i) Adverse reactions to cosmetic hair treatments. (a–c) Hair matting. (d, e) Bubble hair. (f, g) Cosmetic hair beads (Courtesy of Prof. P. Itin). (h, i) Central centrifugal cicatricial alopecia (formerly, hot comb alopecia)
Since the structure of the hair is significantly damaged, the only alternative is to cut off the tangled portion.
The best means of prevention in damaged hair is to follow the instructions for using shampoo products and to regularly use conditioner, especially for permed hair.
6.7.2 Bubble Hair
Bubble hair is an acquired hair shaft abnormality characterized by a localized area of weak, dry, and brittle hair which breaks easily and bubble-like areas in the hair shaft seen with light microscopy. The overall texture of the hair may change from soft and naturally curly to straight and stiff. Bubble hair is a reproducible hair shaft defect caused by heat. Brief, focal heating of damp hair is sufficient to cause bubbles to form inside the hair fibers (Fig. 6.7d, e).
The use of overheating hair dryers, or any other hair care equipment that overheats, should be avoided.
6.7.3 Cosmetically Induced Hair Beads
Cosmetically induced hair beads present as monilethrix-like appearance of hair shafts through buildup of polymers (PVP, vinyl acetate, methacrylates) on hair as a result of excessive use of hair lacquer and hairstyling gel. Light microscopy reveals that the hair is encircled by a material with a glassy appearance (Fig. 6.7f, g).
6.7.4 Others (Peculiar to African Hair)
Central centrifugal cicatricial alopecia represents a well-defined area of partial hair loss over the top of the heads seen almost exclusively in patients of African origin (Fig. 6.7h, i) and presumably related to peculiarities of African hair anatomy and grooming habits, including excessive use of heat for the purpose of stretching the hair (hot comb alopecia) and traction.
Therapeutic options are limited to the use of a compound of topical 5 % minoxidil and 0.2 % triamcinolone acetonide combined with oral doxycycline; therefore, the goal of treatment is to prevent progression of disease through avoidance of traction, chemicals, and heat, since once scar formation has occurred, it remains irreversible.
Adverse effects have also been reported by persons who used a commercial hair-straightening product known as the Rio Hair Naturalizer System (World Rio Corporation). Most reported substantial hair loss, with a majority indicating growth of new hair that was abnormal in both quantity and quality.
Suggested Reading
Hair Weathering
Hofbauer GF, Tsambaos D, Spycher MA, Trüeb RM (2001) Acquired hair fragility in pili annulati: causal relationship with androgenetic alopecia. Dermatology 203:60–62PubMedCrossRef
Sinclair R (2007) Healthy hair: what is it? J Invest Dermatol Symp Proc 12:2–5CrossRef
Trüeb RM (2005) Dermocosmetic aspects of hair and scalp. J Investig Dermatol Symp Proc 10:289–292
Shampoos
Ackerman AB, Kligman AM (1969) Some observations on dandruff. J Soc Cosm Chem 20:81–101
Adams RM, Maibach HI (1985) A five-year study of cosmetic reactions. J Am Acad Dermatol 13:1062–1069PubMedCrossRef
Baroni A, de Rosa R, de Rosa A et al (2000) New strategies in dandruff treatment: growth control of Malassezia ovalis. Dermatology 201:332–336PubMedCrossRef
Bouillon C (1996) Shampoos. Clin Dermatol 14:113–121PubMedCrossRef
Dawber R (1996) Hair: its structure and response to cosmetic preparations. Clin Dermatol 14:105–112PubMedCrossRef
Georgalas A (2004) Enhanced delivery of antidandruff active in shampoo vehicle. J Cosmet Sci 55(Suppl):S207–S214PubMed
Goldschmidt JA, Kligman AM (1968) Increased sebum secretion following selenium sulfide shampoos. Acta Derm Venereol 48:489–491PubMed
Hay RJ, Graham-Brown RAC (1997) Dandruff and seborrhoeic dermatitis: causes and management. Clin Exp Dermatol 22:3–6PubMedCrossRef
Hughes-Formella BJ, Filbry A, Gassmueller J, Rippke F (2002) Anti-inflammatory efficacy of topical preparations with 10 % hamamelis distillate in a UV erythema test. Skin Pharmacol Appl Skin Physiol 15:125–132PubMedCrossRef
Korting HC, Schäfer-Korting M, Klövekorn W et al (1995) Comparative efficacy of hamamelis distillate and hydrocortisone cream in atopic eczema. Eur J Clin Pharmacol 48:461–465PubMedCrossRef
Merk HF, Mukhtar H, Kaufmann I et al (1987) Human hair follicle benzo[a]pyrene and benzo[a]pyrene 7,8-diol metabolism: effect of exposure to a coal tar containing shampoo. J Invest Dermatol 88:71–76PubMedCrossRef
Rushton H, Gummer CL, Flasch H (1994) 2-in-1 shampoo technology: state of the art shampoo and conditioner in one. Skin Pharmacol 7:78–83
Schuster S (1984) The aetiology of dandruff and the mode of action of therapeutic agents. Br J Dermatol 111:235–242CrossRef
Shapiro J, Maddin S (1996) Medicated shampoos. Clin Dermatol 14:123–128PubMedCrossRef
Trüeb RM (2005) Dermocosmetic aspects of hair and scalp. J Investig Dermatol Symp Proc 10:289–292
Trüeb RM (2007) Shampoos: ingredients, efficacy and adverse effects. J Dtsch Dermatol Ges 5:356–365
Urbano CC (1995) 50 years of hair care development. Cosmet Toiletries 110:85–104
Van Schooten FJ, Moonen EJ, Rhynsburger E et al (1994) Dermal uptake of polycyclic aromatic hydrocarbons after hair wash with coal tar shampoo. Lancet 344:1505–1506PubMedCrossRef
Conditioners
Rushton H, Gummer CL, Flasch H (1994) 2-in-1 shampoo technology: state of the art shampoo and conditioner in one. Skin Pharmacol 7:78–83
Trüeb RM (2005) Dermocosmetic aspects of hair and scalp. J Investig Dermatol Symp Proc 10:289–292
Trüeb RM (2007) Shampoos: ingredients, efficacy and adverse effects. J Dtsch Dermatol Ges 5:356–365
Hairstyling Aids
Draelos ZD (2005) Hair grooming cosmetics. In: Draelos ZD (ed) Hair care. An ilustrated dermatologic handbook. Taylor & Francis, London/New York, p 75
Hair Dyes
Bolt HM, Golka K (2007) The debate on carcinogenicity of permanent hair dyes: new insights. Crit Rev Toxicol 37:521–536PubMedCrossRef
Kelsh MA, Alexander DD, Kalmes RM, Buffler PA (2008) Personal use of hair dyes and risk of bladder cancer: a meta-analysis of epidemiologic data. Cancer Causes Control 19:549–558PubMedCrossRef
Mendelsohn JB, Li QZ, Ji BT et al (2009) Personal use of hair dye and cancer risk in a prospective cohort of Chinese women. Cancer Sci 100:1088–1091PubMedCentralPubMedCrossRef
Pande CM, Albrecht L, Yang B (2001) Hair photoprotection by dyes. J Cosmet Sci 52:377–389
Rollison DE, Helzlsouer KJ, Pinney SM (2006) Personal hair dye use and cancer: a systematic literature review and evaluation of exposure assessment in studies published since 1992. J Toxicol Environ Health B Crit Rev 9:413–439PubMedCrossRef
Tosti A, Piraccini BM, van Neste DJ (2001) Telogen effluvium after allergic contact dermatitis of the scalp. Arch Dermatol 137:187–190PubMed
Cosmetic Treatment for Aging Hair
Bangha E, Elsner P, Kistler GS (1996) Suppression of UV-induced erythema by topical treatment with melatonin (N-acetyl-5-methoxytryptamine). Arch Dermatol Res 288:522–526PubMedCrossRef
Draelos ZD (2010) Care of aging hair and photoprotection. In: Trüeb RM, Tobin DJ (eds) Aging hair. Springer, Berlin/Heidelberg, pp 183–191CrossRef
Fischer TW, Scholz G, Knoll B et al (2001) Melatonin reduces UV-induced reactive oxygen species in a dose-dependent manner in IL-3-stimulated leukocytes. J Pineal Res 31:39–45PubMedCrossRef
Gao T, Bedell A (2001) Ultraviolet damage on natural gray hair and ist photoprotection. J Cosmet Sci 52:103–118PubMed
Pande CM, Albrecht L, Yang B (2001) Hair photoprotection by dyes. J Cosmet Sci 52:377–389
Wissing SA, Muller RH (2001) Solid lipid nanoparticles (SLN) – a novel carrier for UV blockers. Pharmazie 56:783–786PubMed
Adverse Effects of Cosmetic Hair Treatments
Al-Ghani MA et al (2000) Matting of hair: a multifactorial enigma. Dermatology 20:101–104
Hair Matting
Al-Ghani MA et al (2000) Matting of hair: a multifactorial enigma. Dermatology 20:101–104
Bubble Hair
Gummer CL (1994) Bubble hair: a cosmetic abnormality caused by brief, focal heating of damp hair fibers. Br J Dermatol 131:9801–9903CrossRef
Cosmetically Induced Hair Beads
Itin P, Schiller P, Mathys D, Guggenheim R (1997) Cosmetically induced hair beads. JAAD 36:260–261CrossRef
Others (Peculiar to African Hair)
Callender VD, Onwudiwe O (2011) Prevalence and etiology of central centrifugal cicatricial alopecia. Arch Dermatol 147:972–974PubMedCrossRef
Gathers RC, Lim HW (2009) Central centrifugal cicatricial alopecia: past, present, and future. J Am Acad Dermatol 60:660–668PubMedCrossRef
Gathers RC, Jankowski M, Eide M, Lim HW (2009) Hair grooming practices and central centrifugal cicatricial alopecia. J Am Acad Dermatol 60:574–578PubMedCrossRef
Khumalo NP (2011) Prevalence of central centrifugal cicatricial alopecia. Arch Dermatol 147:1453–1454PubMedCrossRef
Khumalo NP, Gumedze F (2012) Traction: risk factor or co-incidence in central centrifugal cicatricial alopecia? Br J Dermatol 167:1191–1193. doi:10.1111/j.1365-2133.2012.11050.xPubMedCrossRef
Kyei A, Bergfeld WF, Piliang M, Summers P (2011) Medical and environmental risk factors for the development of central centrifugal cicatricial alopecia: a population study. Arch Dermatol 147:909–914PubMedCrossRef
LoPresti P, Papa CM, Kligman AM (1968) Hot comb alopecia. Arch Dermatol 98:234–238PubMedCrossRef
Shah SK, Alexis AF (2010) Central centrifugal cicatricial alopecia: retrospective chart review. J Cutan Med Surg 14:212–222PubMed
Summers P, Kyei A, Bergfeld W (2011) Central centrifugal cicatricial alopecia – an approach to diagnosis and management. Int J Dermatol 50:1457–1464PubMedCrossRef
Swee W, Klontz KC, Lambert LA (2000) A nationwide outbreak of alopecia associated with the use of a hair-relaxing formulation. Arch Dermatol 136:1104–1108PubMed
Whiting DA, Olsen EA (2008) Central centrifugal cicatricial alopecia. Dermatol Ther 21:268–278PubMedCrossRef