Hair dye allergies affect about 5% of the people who use permanent hair dyes. The allergic reaction caused in these cases is usually a form of allergic contact dermatitis. The allergic reaction is usually localized to the head area, and causes redness and itching in the affected region. Scalp, neck, face, and back areas may also get affected in some cases.
Hair stylists who handle the hair dyes (with bare skin) on a regular basis may also get dermatitis of the hands. Widespread allergic reaction involving the organs and skin all over the body is also possible in some rare cases. The main cause of hair dye allergies is a widely used component of the hair dyes known as 4-paraphenylenediamine (commonly abbreviated as PPD).
Contact with a specific form of this allergen may cause an itching or burning sensation on the scalp. The symptoms may either being within a short time after hair dye application or take a few days (sometimes weeks) to develop.
Read more on itchy scalp.
What is PPD (4-paraphenylenediamine)?
PPD is also known as PPDA, rodol, ursol, and orsin. Available since 1909, this component is present in many permanent hair dye products in the market. Hair dying products usually come as a pack of two separate products in two separate bottles. In one bottle, a colorless, non-oxidized PPD-based dye is present. In the other bottle, an oxidizer (usually hydrogen peroxide) is present.
During the hair dying process, the hydrogen peroxide oxidizer is used first to break down melanin, which is the natural coloring pigment of the hair and the skin. After that, the PPD-based dye is used to replace the color of the hair. Reaction of PPD with the peroxide oxidizes PPD and makes it colored.
The fully oxidized form of PPD does not cause allergy. However, a partially oxidized form of PPD can cause allergy in PPD-sensitive individuals. Apart from hair dyes, PPD is also found in temporary tattoos and dark-colored cosmetics. PPD is also used to dye fur coats. Due to its potential toxic effects, PPD was banned in hair dye products in France, Sweden and Germany.
Other hair-dye allergens
Apart from PPD, other substances in the hair dye products may also be responsible for an allergic reaction. Examples of such substances include isatin, 6-hydroxyindole, and p-methylaminophenol.
Allergens related to PPD include the following:
- Compounds with azo groups (present in temporary hair dyes, gasoline, food coloring agents, inks within ballpoint pens, and certain medicines).
- Sulfa drugs.
- Procaine and benzocaine (local anesthetics).
- Para-aminosalicylic acid (used in the treatment of tuberculosis).
- Para-aminobenzoic acid (used in sunscreen creams).
It is important to be vigilant about the substances present in hair dye products because manufacturers of these products may at times use misleading marketing approaches. For example, allergic reactions are still possible with hair dyes that are labeled as “hypoallergenic”, “natural”, “unscented” or “fragrance-free”.
When in doubt about the terminology used to describe a product’s ingredients and their possible effects, one should seek advice from a certified hair-styling professional or a doctor. Also, it is important to remember that allergic reactions only affect individuals who are hypersensitive to certain substances. Not everybody who is exposed to an allergen will be affected.
Types of Hair Dye Allergies
The following are the main types of allergic reactions that may be caused by hair dyes.
Allergic contact dermatitis
Allergic contact dermatitis is the most common type of allergic reaction due to hair dye use. It is caused when a genetically predisposed individual comes in contact with PPD. The risk of developing sensitivity to PPD also increases with increased frequency of hair dye use. Initial sensitivity to PPD takes at least 10 days (after the first use of PPD) to develop. After developing sensitivity, a person may experience an allergic reaction within 6-72 hours of second (or subsequent) exposure to PPD.
This is technically referred to as delayed hypersensitivity. During the allergic reaction, the macrophages and lymphocytes target the PPD molecules and cause formation of skin redness, granulomas and vesicles. The most commonly affected areas include the skin at the hairline, ears, eyelids, beard and neck. An itching or burning sensation occurs in these areas. The location of skin irritation may also extend well beyond the point of skin contact with PPD.
In contact urticaria, exposure to PPD triggers release of histamine and production of IgE antibodies. Histamine causes increased porosity and dilation of cutaneous blood vessels. This causes edema due to seepage of plasma from the blood vessels into the tissue spaces of the skin. The affected skin areas also become red.
The signs and symptoms of contact urticaria take about a minute to an hour to develop. In some cases, red patches may appear all over the body. This may be accompanied by sneezing, bronchial asthma, vomiting, and difficulty in swallowing. This condition is known as contact urticaria syndrome (abbreviated as CUS).
Anaphylactic shock is a life-threatening emergency that rarely occurs due to hair dye allergy. The signs and symptoms include facial swelling, drop in blood pressure, and difficulty in breathing. In the absence of immediate medical treatment, death may also occur.
Diagnosis (Allergy Sensitivity Test)
Not everybody who uses a hair dye develops an allergic reaction to it. However, there is always a possibility that one may be sensitive to certain components present in hair dye products. Therefore, it is strongly advisable to undergo an allergy sensitivity test before adopting a particular hair dye product.
Users of hair dyes can perform an allergy sensitivity test themselves by applying a little hair dye solution (dye mixed with developer or oxidiser) on the inner side of the elbow or behind the ear. If no skin irritation (such as burning or itching sensation) or skin rash develops in the next 48-72 hours, then one may proceed to use the hair dye product. However, if a skin rash or skin irritation develops, then one should not use that particular hair dye product.
Dermatologists use a skin patch test to determine if a person is sensitive to certain allergens. A patch containing 2% PPD in petrolatum is stuck to the skin on the upper back, which is examined after 48 hours. If a person is allergic to PPD, skin rashes, blisters or ulcers may develop on the back. A ready-to-use T.R.U.E. patch containing 24 putative allergens (including PPD) is also available for testing multiple allergic sensitivities at once.
Treatment of PPD Allergy
When an acute allergic reaction to hair dye develops, the hair and scalp should be washed with a mild shampoo to remove the hair dye from the hair. Also, a 2% solution of hydrogen peroxide should be applied to the affected areas in order to completely oxidize PPD. A 1:5000 dilution of potassium permanganate can also be used for this oxidation reaction.
A wet dressing of lime or olive oil may be used to soften the crust. However, one must consult with a doctor before undertaking these steps. Once the reaction is contained, an allergic testing for PPD should be done. If an allergic reaction to PPD is found, then the doctor may prescribe a corticosteroid cream for application to the affected areas. It is important to note that an individual found allergic to PPD should not use any hair dye products.