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Reactions to Hair Dye

Reactions of one kind or another to the use of hair-dye products are not that uncommon. They range from irritation occurring locally in areas in direct contact with the dye (irritant contact dermatitis) to 'genuine' allergy which will provoke local symptoms (allergic contact dermatitis) but may also produce a systemic reaction affecting other areas of the body. In both cases, the symptoms can vary from very mild to quite severe. The local irritation will tend to affect the scalp, neck, forehead, ears and eyelids; the generalised symptoms may include more widespread itching, urticaria (nettle rash), general unwellness or, rarely, anaphylaxis.

Hair-dye products contain a wide range of chemicals and almost any of these could trigger sensitivity reactions. However, there are a group of well recognised culprits.

Paraphenylenediamine (PPD) is found in permanent hair dyes, especially those at the darker / black end of the range. These systems usually require the use of two components; the PPD-based dye in one bottle together with various other chemicals (e.g. resorcinol to vary the colour tone; ammonia which is necessary for the chemical reaction), and an oxygen-providing 'fixative' (usually hydrogen peroxide) in the second bottle. PPD is actually colourless but becomes coloured when oxidised by the release of oxygen from the second bottle. It is during the oxidation process that the chemical acts as a sensitiser - hence once the process is complete the dye is generally 'safe' and does not continue to cause problems once the initial symptoms have settled down (although this may take many days).

Because PPD is known to be a strong sensitiser in some people, other chemicals have been used as alternatives in an attempt to produce safer hair-dye products. Para-aminodiphenylamine (PADA) and paratoluene diamine (PTDA) and 3-nitro-p-hydroxyethylaminophenol (usually found in dyes at the less dark, 'redder' end of the spectrum) are somewhat less troublesome than PPD, but can still cause sensitivity problems and if you have already been triggered, it is quite likely that these will also upset you. Thus for the patient who has become sensitised, there are no 'safe' permanent hair dyes, only slightly 'safer' ones.

Cross-reactivity will occur in a moderate number of patients who have become sensitised to one of these chemicals. Typically, they may also then react to azo dyes (used in temporary hair dyes, foods and medications), local anaesthetics such as benzocaine (used in dental work or minor surgery), sulphur-antibiotics (rarely used these days), and para-amino benzoic acid (PABA - a preservative widely used in sunscreens, creams and lotions).

There are several approaches to the problem of hair-dye, but none of them are easy!

  • Stop using hair dyes altogether. The only truly safe option - although if you are one of the unfortunate few who have developed cross-sensitivity to some of the other chemicals mentioned above such as azo-dyes in foods, you may still have to avoid those, or keep a careful watch for symptoms that might be arising from their use.
  • Try and find a safe alternative. As mentioned above, there are really no 'safe' products, but there may be a product that is safe for you. In order to find it, you could follow one of two routes:
    1. Undergo formal patch testing at an allergy (dermatology) clinic. The main chemicals that cause problems in hair-dyes are well known, and are available in patch-test form. The clinic will test a range of these chemicals (as well as other potential sensitisers such as formaldehyde) and will then tell you which ones you are sensitive to. You can then look for products that are free of the offending chemicals. There are drawbacks with this plan - getting referred; waiting lists; the limited number of chemicals tested - they can't test everything, and you may be sensitive to something they haven't tested, that could then cause a problem if it is in the product that you choose to use.
    2. Patch test a range of products yourself (unless you have suffered a severe reaction from hair dyes previously). This has the advantage that you test the whole product, although if you react to some of them you won't know exactly what component is causing the problem, unless you keep very careful notes and can work it out by a process of elimination. Patch test by dabbing a small amount of the dye solution either behind the ear or on the inner elbow, leave to dry, and leave uncovered for 48hrs. If any irritation, rash or unwellness occurs then do not use the product (and wash it off your skin immediately). Note that if it is a 2-bottle product, you will need to mix a small amount of solution from each bottle and use this mixed solution for the test.

      When choosing products, switch to non-permanent hair dyes. These generally use different, less troublesome chemicals, although about 10% of people sensitised to PPD will suffer allergic sensitivity to non-permanent dyes as well. You may well be lucky - however if your skin is inflamed from previous reactions even these may cause irritation unless you wait until any existing lesions or patches of inflammation have thoroughly settled. Henna or vegetable dyes available from 'green' shops and some chemists & hairdressers are probably the safest option, but even these may sometimes contain azo-dyes (see above).

Finally, as with all allergy and chemical-sensitivity problems, it is important to sensibly reduce exposure to unnecessary chemical exposure, and maintain good levels of vitamins and minerals by eating a varied, balanced diet, or using broad-spectrum nutritional supplements if the diet has to be restricted.


Last updated: March 2012