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p>Hair is an important part of body and a major factor in self-image. A wide variety of hair cosmetic preparations are available and are used regularly by most of the world’s population. Hair colouring is one of the commonly done procedure. However, any chemical treatment, normal grooming habits and environmental exposure can produce changes in hair texture or hair breakage. It is necessary for a dermatologist to know the basis of hair colouring, the procedure and the possible side effects it can cause. Also post colour care is also to be known about to prevent further damage to treated hair. This article explains the basic chemistry and mechanism involved in hair dyeing and the basic facts a dermatologist should know.</p
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International Journal of Research in Dermatology | May-June 2021 | Vol 7 | Issue 3 Page 496
International Journal of Research in Dermatology
George NM et al. Int J Res Dermatol. 2021 May;7(3):496-502
Review Article
Hair colouring: what a dermatologist should know?
Neethu Mary George*, Amruthavalli Potlapati
Hair is present in various colours and textures varying
with race and ethnicity. Hair colour is determined by the
melanocytes found only in the matrix area of the follicle
at the base of the cortex directly above the follicular
papilla. Eumelanin is the main pigment found in
black/brown hair and pheomelanin is the predominant
pigment found in blond/red hair. The hair shaft
documents the history of the cosmetic practices of an
Hair colouring is a procedure commonly used by both
elderly people to conceal their grey hair and youth to
achieve a new fashionable colour shade.
A wide variety of natural and synthetic hair-colouring
agents is available. Vegetable and metallic dyes are
natural colourants, but these have largely been replaced
by synthetic dyes. Hair dyes can last longer on
chemically treated hair as this hair is porous and
unexpected colours can result on chemically treated hair.1
Hair dyes are classified, non-oxidative and oxidative
dyes. Non-oxidative coloration is further divided into two
groups, temporary and semi-permanent colorants.
Oxidative colouring is also divided into three groups,
permanent, demi permanent and auto-oxidation dyeing.
Hair consists of a long polymeric structure where peptide
chains are held together by various chemical interactions
such as covalent bonds (disulphide linkage), hydrogen
bonds, ionic and hydrophobic interactions. Among them,
disulphide linkage is particularly important for shaping
the mechanical properties of the hair fibre.2 The hair shaft
is divided into four main distinct structures: cuticle,
cortex, cell membrane complex (CMC) and the medulla.3
The cuticles are the most external part of the hair strand
and keep its physical properties. They regulate the
adsorption and diffusion of various active ingredients
during bleaching, dyeing and hair treatments. It contains
six to ten layers of overlapping cells and each cuticle cell
contains an external thin membrane formed by a layer of
fatty acid, responsible for the hydrophobic character of
the fiber.4
Department of Dermatology, Marsleeva Medicity, Pala, Kerala, India
Received: 21 March 2021
Accepted: 13 April 2021
Dr. Neethu Mary George,
Copyright: © the author(s), publisher and licensee Medip Academy. This is an open-access article distributed under
the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial
use, distribution, and reproduction in any medium, provided the original work is properly cited.
Hair is an important part of body and a major factor in self-image. A wide variety of hair cosmetic preparations are
available and are used regularly by most of the world’s population. Hair colouring is one of the commonly done
procedure. However, any chemical treatment, normal grooming habits and environmental exposure can produce
changes in hair texture or hair breakage. It is necessary for a dermatologist to know the basis of hair colouring, the
procedure and the possible side effects it can cause. Also post colour care is also to be known about to prevent further
damage to treated hair. This article explains the basic chemistry and mechanism involved in hair dyeing and the basic
facts a dermatologist should know.
Keywords: Hair colouring, Paraphenylenediamine, Bleaching, Hair dye, Allergic contact dermatitis
George NM et al. Int J Res Dermatol. 2021 May;7(3):496-502
International Journal of Research in Dermatology | May-June 2021 | Vol 7 | Issue 3 Page 497
The cortex forms the matrix where other proteins and
keratin are located, and composes the larger part of the
fibrous mass of human hair. They consist of cells filled
with keratin and provides mechanical properties to the
fibers.5 The cortical cells, adjacent to the cuticle, are
flatter and contain less sulphur than the cells inside the
cortex, which are rich in cystine, amino acids, lysine and
histidine, in addition to the melanin granules.6 The
consequently lower amount of disulphide crosslinks
leaves non-keratinous proteins more labile and less
resistant to chemical attack than the cystine rich
keratinous components of the fibre.7
The matrix comprises the major structure of the hair and
contains a high concentration of disulphide bonds. It
presents considerable swelling when in contact with
water. It exhibits keratin macro-fibrils aligned in the
direction of the hair strand and melanin granules which
are responsible for the hair colour and its photo
protection. The CMC consist of cell membranes and
adhesive material that “glue” or link the cortical and the
cuticle cells. Chemically, CMC is composed of proteins,
polysaccharides, and ceramides. It is also responsible for
the hair’s natural moisture, making it bright, transparent,
and hydrated.
The medulla is the innermost region and its presence
along the hair is usually discontinuous or even absent and
does not interfere with the hair structure.7 The medulla
can be empty or filled with sponge keratin and has high
lipid concentration, can serve as a pigment reservoir, and
can contribute to the brightness of the hair.
Hair dying systems can be divided into two main
categories, oxidative or non-oxidative, and also according
to the colour durability after the application on hair
strands: temporary, semipermanent, demi permanent and
Temporary hair colour
They are non-oxidative dyes, with high molecular weight
and get deposited on the hair surface post colouring. As
there is no oxidising agent, it doesn’t penetrate the cortex.
They are anionic and hence highly water soluble and can
be removed easily in first shampoo wash. It doesn’t
bleach the hair and hence if the original hair colour is
black, it is not usually seen and they do not have the
power of whitening the hair strand. Because of high
molecular weight, it covers only 15% of grey hair. These
formulas are easy to use and carry little risk of contact
dermatitis. However, these dyes readily stain the scalp
and skin. The temporary non-oxidative formulations as
single applications, present higher dye concentrations,
ranging from 0.1% to 2.0% (w/w) and have the purpose
of promoting a stronger dyeing effect. The formulation
must get in contact with hair for about 30 min and results
will occur immediately. It is suitable for those who wish
for fantasy colors. It resists from three to six washes
when applied to bleached hair, like semipermanent
dyeing. They are available in powder, shampoos and
crayon formulation
Semi-permanent hair dye
They do not use oxidising agents like hydrogen peroxide.
These formulations contain basic or cationic dyes with
low molar mass, which has a high affinity for hair keratin
and resists from three to six washes. Semi-permanent
dyes consist of nitro aromatic amines or aromatic nitro-
anthraquinone dyes that diffuse into the hair and bind to
the hair, however do not attach firmly. Semi-permanent
hair dyes are generally applied to freshly shampooed hair
and allowed to remain on the hair for approximately 10-
40 minutes and the hair is then rinsed with water. The
product usually contains nitro-aromatic molecules
sometimes mixed with inorganic pigments under neutral
or slightly alkaline pH conditions. They penetrate slightly
in the cortex, especially because of the high pH value of
the product promotes the cuticles opening.8 They last for
5-6 shampoo washings and thus require a reapplication.
They are, however, unable to lighten hair as they do not
contain any bleach. Several products are available in the
market: lotions, shampoos, mousses and emulsions.
Cosmetic forms must have the ideal viscosity so that they
do not flow during the application. These semi-permanent
dyes have the potential to cause allergic contact
dermatitis. They cause only minimum hair damage as it
does not involve any harsh chemical processing.
Demi permanent hair dyes
They are more resistant to shampooing when compared to
the semi-permanent dyes. They are applied with
hydrogen peroxide or other demi permanent hair products
are resistant for up to 20 washes because they consist of a
mix of semipermanent molecules with oxidation dye
precursors, applied with hydrogen peroxide (H2O2). In
demi-permanent dyeing, melanin is bleached to a lesser
extent. This product utilises a small amount of mono-
ethanolamine as an alkaliser to get a pH level of 7-8.
Because it doesn’t involve high level of melanin
bleaching, it may offer superior hair quality. However, it
gives very few colour shades and exhibits poor colour
Permanent hair dyes
Majority in the market belong to this category. They
cover up to 100% of white hair strands. Also, it is
possible to have dark and light natural hair colour due to
the combination of the oxidizing agents with the
ammonia hydroxide.1 They cause permanent dyeing,
resistance to shampoo washes and other external factors,
such as drying, friction, light, and others. The principal
difference between the demi permanent hair dye in
comparison with a permanent one is the alkalizing agent
used because, in the first, mono-ethanolamine with low
George NM et al. Int J Res Dermatol. 2021 May;7(3):496-502
International Journal of Research in Dermatology | May-June 2021 | Vol 7 | Issue 3 Page 498
color lightening power is used.9 Permanent dyes have the
potential to damage the hair shaft. They utilize a series of
chemical processes within a single application and all
forms must be mixed with hydrogen peroxide before
application, without which they are ineffective. The
active ingredients penetrate the hair first and then react to
form a new chromophore inside hair fibre.
The colour formation is based on a series of oxidation
and coupling reactions and require four major
components: the coupling bases; the reaction modifiers;
an alkalizing compound; and an oxidizing agent.
Coupling bases
Bases are aromatic compounds derived from benzene,
substituted by at least two electron donor groups such as
NH2 and OH in para or ortho positions for easy oxidation,
acting as a colour developer.10
Reaction modifiers/couplers
The modifiers are aromatic m-phenylenediamines,
resorcinol, naphthol and other derivatives.11 They are
aromatic compounds derived from benzene and
substituted by groups such as NH2 and OH in the meta
position, which does not present easy oxidation by H2O2.
They do not produce significant colour alone yield only
feeble colouring through oxidation but can modify them
when used with primary intermediaries and oxidants.10
determine the final shade of the colour after reaction with
the oxidized form of the primary intermediate. Hydrogen
peroxide oxidises the primary to a highly electrophilic
intermediate which then couples with the coupler.
Alkalizing compound
This is necessary to promote the proper pH value for the
beginning of the oxidation reaction. The most commonly
alkalizing compounds used are ammonia (as ammonium
hydroxide) and mono-ethanolamine (MEA) when the
formulation contains water, or sodium silicate when it is
in solid form (powder). When ammonia helps to remove
the natural pigments present in hair as the melanin and in
coverage of 100% of white hairs. After the formation of
the coloured polymer in inner of cortex, its complete
removal is not possible and hence its permanent.
However, MEA does not oxidize melanin. Thus, products
containing MEA instead of ammonia hydroxide are
suitable for maintenance of similar shades or to dark
Oxidising agents
There are basically two types of oxidants used: hydrogen
peroxide, when the vehicle is water, and sodium
persulfate, when it is a powder.
Reducing agents
Reducing agents are added to oxidative dye formulations
to retard the reaction between bases and reaction
modifiers and to prevent the initiation of the reaction in
the packaging tube during the storage time. e. g., sodium
metabisulfite (MBS).
Antioxidants are necessary to avoid the reaction
beginning before the addition of the oxidant itself. A
water-soluble antioxidant can prevent the manipulation of
bases and initiation of oxidative reaction by reaction
modifiers, which may interfere with the final colour of
the product. E. g., erythorbic acid (AEB). An oil-soluble
antioxidant is used as a vehicle for emulsion hair dyes
because this avoids the yellowing of wax and the
oxidation of bases and reaction modifiers. e.g., T-butyl
quinone (TBQ).12
The oxidative dye is available as emulsion (most
commonly used), gels, solutions (liquid), and powders.
The peroxides are very unstable, requiring the use of
stabilizers such as sodium stannate and the penta sodium
pentetate. A mixture of surfactants and solvents is used to
disperse dye molecules and ensure hair wetting.
Categories of contents commonly seen in hair dye (Table
To achieve a shade closer to hair colour, a single step
process of hair dyeing is only needed. To achieve a light
shade, a two-step process is done; bleaching with
hydrogen peroxide and ammonium and potassium
persulphate, and then dyeing is done.
Hair bleaching: It is commonly used by both elderly
people to conceal their grey hair and youth to achieve a
new fashionable colour shade. It is believed that the
bleaching process begins with the gradual solubilisation
of the melanin in hydrogen peroxide at high pH which
may detach pigment grains from the hair proteins. The
dissolved melanin is fairly easily broken down or
depolymerised to carboxylate derivatives that are
removed on rinse off.13,14 Bleaching can also lead to
oxidation of protein components of the hair fibre.
Oxidation of cystine cleaves disulphide linkage
generating cystic acid. This alters the electrostatic
properties of fibre and creates anionic sites which can
subsequently lead to higher metal uptake. As the
disulphide bond contributes to the tensile properties of
the fibre, its cleavage leaves hair fragile and damaged.15
George NM et al. Int J Res Dermatol. 2021 May;7(3):496-502
International Journal of Research in Dermatology | May-June 2021 | Vol 7 | Issue 3 Page 499
Bleached hairs showed apparent breaking and fracturing
from the leading edge in the cuticle’s scales. When the
bleached hairs are re-treated with the bleaching agent, the
cuticles were not only lifted but also removed from the
hair surface. This is why bleached hair fibres present low
tensile strength, high porosity and poor sensorial
Table 1: Categories of contents in hair dye.
Hydrogen peroxide
Sodium metabisulfite (MBS)
Sodium stannate and the penta sodium
Ammonia (as ammonium hydroxide)
and monoethanolamine (MEA)
phenols, meta disubstituted
phenylenediamines and
phenyleneaminophenols, and various
resorcinol (1,3-dihydroxybenzene)
O-nitro anilines (gives yellow and
orange shades), aminonitrophenols
and their ethers (gives yellow and
orange shades), Azo dyes (gives
yellow and orange shades),
nitrodiphenylamines (gives 'orange to
red shades), nitrophenyienediamines
(gives colour in the range red to
violet), anthraquinone (Gives violet to
blue shades).
Parabens, phenoxyethanol
Homoxalate, Octinosate, Octocrylene,
Sodium lauryl sulfate (SLS), sodium
laureth sulfate (SLES), disodium
laureth sulfosuccinate (DSLESS),
disodium lauryl sulfosuccinate
(DSLSS), capramidopropylbetaine,
sodium lauroyl methyl isethionate
(SLMI), cocamidopropyl betaine
(CAPB), capryl/capamidopropyl
betaine, sodium cocoamphoacetate
Oleth-23, cetaryl alcohol
Fragrance, avocado oil, sunflower oil,
olive oil, Dimethicone (conditioning
Quaternium-80, benzyl alcohol, and
During the permanent dyeing process, the mixture
containing the primary intermediate (e. g., p-
phenylenediamine) and the coupling agent (e.g.,
resorcinol) in alkaline medium (ammonia) is mixed with
a hydrogen peroxide solution forming a paste with pH 9,
5. The mixture is applied to the hair and the precursors
and hydrogen peroxide diffuse into the hair strand, where
after specific chemical reactions a coloured compound
with a high molar mass is formed. The first step is the
oxidation of primary to give a reactive intermediate.
Under alkaline conditions in the presence of hydrogen
peroxide, p-phenylenediamine is oxidised to give quinone
diimine (QDI+). They react with the coupler, form the
leuco dye (colourless). This is converted into the
indoaniline dye within the hair strand. The intermediate
compounds have similar sizes and, therefore, an easy and
uniform penetration occurs inside the hair.18 The hair
surface in untreated hair has a pH of 4.5 to 5.5. This
acidic pH helps to keep the cuticular cells closely
opposed to the cortex.19 The reaction occurs in an
alkaline medium that promotes the opening of the cuticles
that allows the penetration of the dyes’ molecules into the
cortex. Primaries are oxidised inside the hair to give
reactive intermediates which then react with the couplers.
This reaction yields a new chromophore imparting a new
colour shade to the fibre. The new chromophore is bigger
in size than the starting precursors and thus cannot
diffuse out of the fibre easily. Part of the reaction also
happens on the cuticles and the molecules are removed in
the first washes. In the absence of a coupler, oxidation of
the intermediate can form coloured polynuclear
compounds generated by the reaction between the
diimine and the original amine forming Bandrowski base.
Beside oxidation of dye precursors, hydrogen peroxide
bleaches naturally occurring melanin pigment inside hair
fibre and its decomposition products are subsequently
removed during rinse off.
Various parameters may affect the colour formation in
the hair dyeing process, such as pH, pause time, hair
keratin, and purity of the dye molecule, amongst others.
The variation of the pH value directly influences the
reaction rate because a more alkaline pH favours the
reaction and facilitates the cuticle opening, allowing the
penetration of molecules into the cortex.
The pause time is essential for a complete reaction
between the bases and reaction modifiers to occur.
According to the manufacturer’s guidelines, the product
must be in contact with the hair from 30 to 45 min after
application because it is then possible to ensure colour
reproduction and durability to washing.
There are other permanent hair-dye products which
produce progressive hair colouration (by reacting with
the sulphur of hair keratin) which are not formulated with
oxidative hair dyes. They produce gradually a darkening
of the hair. Lead acetate and bismuth citrate act as active
ingredients in this type of products.20
A number of herbal and ayurvedic dyes are available in
India under various trade names such as Black Rose hair
dye herbal, optima hair dye, khadi dye, vegetal etc.
Though they claim herbal, many of them warrant for a
sensitivity test prior to application and allergies have
been noticed after application of the same.
George NM et al. Int J Res Dermatol. 2021 May;7(3):496-502
International Journal of Research in Dermatology | May-June 2021 | Vol 7 | Issue 3 Page 500
Henna (Lawsonia alba), is a natural organic substance,
and is the most widely used vegetable dye for hair,
providing reddish orange shades. In some commercial
products, it is mixed with other dyes to increase the range
of colour. It consists of the dried leaves of the Lawsonia
alba plant. Its colouring properties are due to the presence
of the substance 2-hydroxy-1,4-naphthoquinone. Natural
henna is mixed with tea water or coffee water overnight
to make the colour more visible. Indigofera tinctoria is a
natural dye that is available for commercial use as a green
powder. It is mixed with water and applied the same way
as henna; When mixed with henna, the colour results are
Other natural dyes from walnut or logwood are used in
Asian counties to blacken greying hair. Metallic dyes
using the salts of silver, lead or bismuth were
traditionally used by men, as the colour change occurs
gradually and use is limited to darkening the hair.21 The
metals are thought to interact with cysteine in the cuticle
to form metal sulphides and the deposits gradually
accumulate on the cuticle producing brittle, dull hair.
Hair colouring is a commonly done procedure; though
not investigated fully, it is associated with a lot of side
effects. Airborne contact dermatitis, irritant contact
dermatitis, photo contact dermatitis, periorbital eczema,
hand eczema, lichenoid lesions, and lichen planus
pigmentosus-like pigmentary changes were the
commonly observed clinical patterns of hair dye
dermatitis. Paraphenylenediamine (PPD) is the major
culprit responsible for most of the adverse effects.
Contact leukoderma, contact urticaria, lymphomatoid
papulosis, erythema multiforme-like or prurigo nodular
is-like lesions, and anaphylaxis have also occurred with
PPD.22-26 PPD intoxication results in multisystem
involvement and can cause rhabdomyolysis and acute
kidney injury (AKI), flaccid paralysis, severe gastro-
intestinal manifestations, cardiotoxicity and
arrhythmias.27 There are reports of increased risk of
bladder carcinoma in women who use permanent dyes
frequently and for long periods.28 However, a case-
control study conducted at a hospital in Spain with more
than 300 women did not show an increased risk of
developing bladder cancer related to the regular use of
hair dyes.29 It is also mentioned that use of permanent
dyes can have a relevant impact on the risk of developing
acute leukemia in adults.30 Some dermatological and/or
carcinogenic side-effects have been attributed to some
chemicals used as hair dyes.31 Taylor et al described four
cases of leukoderma caused by hair colors.32 In most of
these cases, the cause of selective melanocytotoxicity is
PPD, and depigmentation at patch test sites has also been
reported after a few months of testing.33 Primary
sensitisation can be from sources other than hair dye.
Today, PPD is permitted in the European union at a
concentration of 6% and toluene-2,5-diamine is permitted
at a concentration of 10%.34
A patch test is recommended. Dyes containing para-
toluenediamine sulphate (PTDS) may be an option found
in newer semi-permanent and permanent dyes and up to
50% may be able to tolerate it.35
Open test: On a clean area behind the ear or on the
forearm just below the elbow, the dye mix is applied with
a cotton swab and allowed to dry. If there is no reaction
in 48 to 72 hours, the dye mix can be safely used on the
Another hair colouring method has been followed by
many, who are allergic to normal hair dye, includes,
application of henna leaf paste (mixed with tea/coffee
water and lemon juice) for 45-60 min followed by rinsing
and then treating the hair with indigo powder paste
(powder mixed in warm water) for few hours followed by
rinsing. This gives a shade similar to black if done
repeatedly. But indigo can stain hands and scalp, hence it
is advised to apply only on hair shaft.
Highlighting is a process by which isolated sections of
hair are either lightened or darkened. This is done by the
‘foil method,’ where strands of hair are separated by a
comb and laid over an aluminium foil sheet, and then
painted with a mixture of hydrogen peroxide and
pigment. The foil is then folded, and the contact time
depends upon the shade required.
Dip dyeing where only the tips of hair is dyed. Ombré is
when a gradually increasing shade is applied from
proximal to distal end of hair shaft.
Shampoos with cationic surfactant is preferred post
colouring.19 It is mandatory to use conditioners as they
flatten the cuticles and seal the gaps that could expose the
important cortex to environmental damage. Choosing the
right surfactant system and conditioning agents are
important for reducing the colour fade. Significantly
faster colour fading was observed for sodium lauryl
sulphate and sodium lauryl sulphate (surfactants).
Sulphate-free surfactants showed statistically significant
advantages for colour protection shampoos. A
combination of silicone quaternium-22 microemulsion
and silicone UV quat (poly-silicone-19) visibly improves
the colour protection of shampoo formulations. An
increasing level of Poly-silicone-19 correlates with
increasing colour protection. An effective colour
protection shampoo should be based on mild surfactants,
conditioning agents for improved combability and feel of
the hair and UV-filters for protection against fading
induced by UV light.
George NM et al. Int J Res Dermatol. 2021 May;7(3):496-502
International Journal of Research in Dermatology | May-June 2021 | Vol 7 | Issue 3 Page 501
To prevent serial fading of hair dye post colouring, it was
found that polymers with hydrophobically modified and
cationic functionalities are most effective in preventing
hair dye dissolution in water. A primary example of a
polymer within this category is a cationic terpolymer of
vinylpyrrolidone, dimethylaminopropyl methacrylamide,
and methacryloylamino propyl lauryl-dimonium
Hair colouring is getting common these days and people
want to look young and trendy. However, it is associated
with structural and systemic side effects. Hence, more
developments should come in the field of hair colour to
prevent the side effects and reduce structural side effects.
Funding: No funding sources
Conflict of interest: None declared
Ethical approval: Not required
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Cite this article as: George NM, Potlapati A. Hair
colouring: what a dermatologist should know? Int J
Res Dermatol 2021;7:496-502.
... Można zaaplikować preparat np. za uchem i pozostawić na minimum dwie doby [11]. Sam obraz alergii powstałej na skutek zabiegu koloryzacyjnego zawiera się głównie w zaczerwienieniu skóry, jej pieczeniu lub świądzie, jednak możliwe są poważniejsze objawy uczuleniowe, pojawiające się nawet w późniejszym czasie od wykonania barwienia. ...
... W cięższych przypadkach mówi się nawet o leukodermii spowodowanej preparatem koloryzującym, która także może wynikać z PPD i jego działania toksycznego na komórki pigmentacyjne -melanocyty [11]. Leukodermia to miejscowa utrata pigmentu skórnego spowodowanego kontaktem z substacją chemiczną zawierającą pochodne fenoli [21]. ...
Hair dyeing has been popular since ancient times, when pigments were mainly extracted from plants. With the development of technology and cultural trends, the search began not only for new pigments but also for new substances, which would make hair dyeing more durable and intense. The addition of synthetic compounds to the composition of hair coloring cosmetics, in addition to the indicated benefits also resulted in side effects. The most often listed substances with toxic properties are PPD (p-phenylenediamine), PTD (p-toluenediamine), persulfates (e.g. sodium persulfate), lavson, m-aminophenol or resorcinol. The adverse effects of these substances on the organism of the client or the hairdresser may manifest in the form of skin redness, swelling, purulent rash, urticaria or even chemical leucoderma, asthma or rhinitis.
Hair dyeing is a popular practice dating back to ancient Egyptian times. Initially, hair dye use was restricted to concealing grey and white hairs of the elderly population. However, in recent times, its use is common among the younger generation as a fashion statement. Hair dye contact dermatitis is a common dermatological condition encountered by dermatologists. It is a delayed type of hypersensitivity reaction that commonly affects the scalp and the vicinity of hair line and neck. Para-phenylenediamine (PPD), a synthetic aromatic amine is the most common allergen specifically implicated in hair dye contact dermatitis. Para-phenylenediamine was announced as the allergen of the year in 2006 by the American Contact Dermatitis Society. Contact allergy to para-phenylenediamine can occur in 0.1–2.3% of the general population. Epicutaneous patch testing is the gold standard test for the diagnosis of hair dye contact dermatitis. However, para-phenylenediamine carries a risk of cross-sensitivity and co-sensitization to other allergens. Apart from contact dermatitis, hair dye use is also associated with various other cutaneous adverse effects such as pigmentary changes, hair loss, skin malignancies and autoimmune disorders. Due to the various adverse effects associated with hair dye use, it is prudent to look for safer alternatives to allergenic hair dyes. In this article, we review the epidemiology, cutaneous and systemic adverse effects associated with hair dye use, patch testing, preventive strategies to minimize the risk of hair dye contact dermatitis, and treatment aspects.
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The objective of this study was to examine the association between personal use of hair dyes and the risk of leukemia. We conducted a systematic literature review of epidemiology studies reporting leukemia-specific cancer risks among hair dye users, and estimated the meta-relative risk (meta-RR) and corresponding 95% confidence interval (95% CI) of leukemia, comparing hair dye users to nonusers. When data from all 20 studies that met the inclusion criteria were combined, ever use of hair dye was associated with a nonstatistically significant increased risk of leukemia, meta-RR = 1.09 (95% CI: 0.97–1.22). When restricted to studies that adjusted for smoking, ever use of hair dye was not associated with leukemia, meta-RR = 0.99 (95% CI: 0.76–1.29). A statistically significant increased risk of leukemia was associated with permanent hair dye use (meta-RR = 1.19 [95% CI: 1.07–1.33]), dark hair dye use (meta-RR = 1.29 [95% CI: 1.11–1.50]), hair dye use among males (meta-RR = 1.42 [95% CI: 1.01–2.00]), hair dye use pre-1980 (meta-RR = 1.49 [95% CI: 1.21–1.83]), and hair dye use for ≥15 years (meta-RR = 1.35 [95% CI: 1.13–1.62]). Overall, findings suggest that ever use of hair dye is not a significant risk factor for leukemia. Certain hair dye use characteristics were associated with a statistically significant increased risk, but further research is required to determine whether these associations truly reflect a risk of leukemia due to methodological limitations in the underlying studies.
Full-text available
Hair color change by dye application is a common procedure among women. Hair dyes are classified, according to color resistance, into temporary, semipermanent, demipermanent and permanent. The first two are based on molecules which are already colored. Temporary dyes act through dye deposition on cuticles, but semipermanent may penetrate a little into the cortex and so the color resists up to six washes. Demipermanent and permanent dyes are based on color precursors, called oxidation dyes, and the final shade is developed by their interactions with an oxidizing agent, but they differ from the alkalizing agent used. In oxidation systems, there is an intense diffusion of the molecules into the cortex, what promotes a longer color resistance. Dyes and color precursors present differences related to chromophore groups, hair fiber affinity, water solubility, and photo stability. The aim of this review is to discuss the differences among hair dye products available in the market and their action mechanisms, molecular structures, application methods, and some aspects of formulations.
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Hair dye poisoning has been emerging as one of the important causes of intentional self harm in the developing world. Hair dyes contain paraphenylene-diamine and a host of other chemicals that can cause rhabdomyolysis, laryngeal edema, severe metabolic acidosis and acute renal failure. Intervention at the right time has been shown to improve the outcome. In this article, we review the various manifestations, clinical features and treatment modalities for hair dye poisoning.
Synopsis--Data on patents for 33 primary intermediates and 20 color modifiers were collected from the literature. The effect of structure on shade, depth of color, light fastness, and solu-bility was determined for each product. The effect on color, depth of shade, and light fast-ness of dyeing mixtures of each of the 20 color modifiers with equimolar quantities of 3 pri-mary intermediates is reported. It is shown that by proper selection of color modifier the shade may be varied, the depth of color greatly increased, the fastness to light increased many fold, and the tendency to turn red on aging decreased. By using the formation of Bandrowski's base from oxidation of p-phenylenediamine as a tool the percentage of conversion to the colored form was shown to be only slightly more than 5% under the conditions normally used for dyeing hair. The effect of various factors on this yield is reported. The results of using five recently described pyridine derivatives are tabulated and dis-cussed.
Cosmetics of the hair, skin, and nails represent an area of great importance to the practicing dermatologist because use of these products can enhance the external appearance, create cutaneous disease, or interfere with other treatment modalities. Furthermore, the dermatologist is the physician best suited to aid patients in appropriate cosmetic product selection and use. This article is an overview of the most important cur-rently marketed cosmetics for the hair, skin, and nails. It discusses the use of hair cosmetics to alter the shape, color, thickness, and cosmetic appearance of the hair. Hair-removal techniques are also discussed. Nail polishes and prostheses to alter nail color and length are examined. Finally, skin cosmetics and toiletries for the face and body in the form of cleansers, toners, exfoliants, masks, moisturizers, specialty creams, and antiperspirants/deodorants are evaluated in terms of formulation, as well as therapeutic versus aesthetic benefit.
Exposure to hair dyes has long been known as a significant risk factor for development of allergic contact dermatitis among the exposed population as these lead to severe eczema of face and upper trunk in the consumer and hand eczema in hair-dressers. Currently, para-phenylenediamine (PPD) is the main ingredient used in permanent hair color products in the market and is the most important allergen. Prevalence of PPD sensitization is high in patients with contact dermatitis across all continents, with hair dye use being the commonest cause. In order to decrease the burden of disease, use of alternative natural dyeing agents among consumers and use of barrier neoprene gloves among hairdressers should be encouraged apart from stringent legislation to reduce the amount of PPD reaching the consumer.
The influence of molecular size and shape and the impact of ionic character on the diffusivity of dyes into human hair fibre have been investigated using advanced molecular modelling techniques. A model has been proposed consistent with current theories on the pathways followed by molecules as they penetrate into the hair fibre and inspired by apparent similarities between the mechanisms involved in hair dyeing and in enzyme and zeolite chemistry. A previously reported method has been extended to take more realistic account of the mechanism of the diffusion process in hair fibres and the motion of the hair dye molecules as they enter the fibres. Original data have been reanalysed mathematically and the interpretation of the results refined. A revised descriptor, LD, the longest dimension of the smallest cross-section of the optimum parallelepiped enclosing the molecule, is proposed as a measure of the diffusivity of the dye into the fibre. Molecular size limit values for dye penetration are proposed varying with the charge on the hair dye molecules.
Finding alternative hair dyes for individuals allergic to para-phenylenediamine (PPD) has been difficult. Newer permanent and demipermanent hair dyes that have replaced PPD with para-toluenediamine sulfate (PTDS) are now available. We examined whether individuals allergic to PPD will tolerate PPD-free hair dyes containing PTDS. A retrospective analysis of patch-test results since October 2006 was done and yielded 28 patients allergic to PPD who were also tested with a hair dye series. From January 2004 through October 2006, seven additional patients allergic to PPD were tested with PTDS but not the full dye series. Patch-test results were analyzed. The newer PTDS dyes were recommended for all PPD-positive PTDS-negative subjects starting in 2008, and these subjects were contacted to determine whether they tolerated the recommended hair-dye products. Of 28 PPD-allergic patients seen since October 2006, 16 (57.1%) tested negative to all other substances on the dye series. Eleven tested positive to PTDS; of these, several were also allergic to other substances in the hair dye series. There was only one patient who was allergic to ortho-nitro-PPD and not to PTDS. Of 7 additional PPD-allergic patients seen from 2004 through 2006, 4 (57.1%) tested negative to PTDS. In total, 20 of 35 individuals (57.1%) tested positive to PPD but negative to PTDS. Ten of 13 PPD-positive patients for whom PTDS hair dyes were recommended subsequently used a PTDS hair dye, and all tolerated these products. Fifty-seven percent of patients allergic to PPD in this study will likely tolerate newer permanent and demipermanent hair dyes based on PTDS. Most individuals not allergic to PTDS will also test negative to other substances in the dye series. All 10 patients who tested positive to PPD and negative to PTDS who subsequently used a PTDS dye free of PPD tolerated these products. Many individuals allergic to PPD will benefit from the newer PTDS-based products.
Hair is commonly colored with synthetic dyes to enhance its appearance or as a fashion statement. The chemistry of permanent hair dyeing technology is based on a 150-year-old observation by Hofmann that p-phenylenediamine produces brown shades on a variety of substrates when exposed to oxidizing agents, including air. The pH of choice for hair dyeing is generally in the range 9-10. At alkaline pH, significant swelling is observed, most likely primarily due to ionization of diacidic amino acid residues. The number of new dye precursors patented over the years, and examples of recent commercial success such as the diamino-N,Ndihydrazopyrazolones, suggest that the oxidative process in an optimized form will remain the dominant technology into the foreseeable future. The rapidly The rapidly developing science of genetics and an emerging understanding of the molecular basis of hair pigmentation may be key elements in the development of systems encouraging natural, biotechnological, or semisynthetic hair repigmentation.
Synopsis The fading of oxidative color in hair as a result of daily shampoo washing activities has become a common problem and a source of frequent complaints by consumers. The fading occurs primarily through hair dye solubility in water. One aspect of the current study investigates the physical and chemical factors that influence hair color fading during the washing process. This is accomplished by testing hair dye dissolution in water from dyed hair samples with variation of surfactant type, pH, and hair type. Furthermore, a new approach to preventing color fading is developed aiming to provide an effective barrier function for hair dye from dissolving into water. The preliminary investigation of a series of polymers with various functional groups indicates that polymers with hydrophobically modified and cationic functionalities are most effective in preventing hair dye dissolution in water. It is also evident that a synergistic effect of the polymer's hydrophobic moieties and cationic charges are important on hair color protection during shampoo washing processes. A primary example of a polymer within this category is a cationic terpolymer of vinylpyrrolidone, dimethylaminopropyl methacrylamide, and methacryloylaminopropyl lauryldimonium chloride (INCI: Polyquaternium-55). The color protection benefit of this polymer is evaluated using newly developed methodologies for evaluating hair color changes, such as hair color fading tests through multiple shampoo washes with mannequin heads and hair tresses, both derived from human hair, colorimetry, and quantitative digital image analysis. In addition, new infrared spectroscopic imaging techniques are used to detect the hair dye deposition behavior inside hair fibers both with and without the color protection treatment. Both visual and instrumental measurement results indicate that Polyquaternium-55 provides a high level of color protection when formulated in a hair color protection regimen with up to 50% color protection. This regimen significantly outperforms commercial products that were tested containing a color protection claim. The proposed mechanism for the anti-fading action of hydrophobically modified polymers includes a cationic charge-reinforced hydrophobic barrier. This model is supported by evaluating the color fastness effect of several different polymer chemistries and by measuring hair surface hydrophobicity changes.