Colouring the hair is a common practice whether it is to hide the greys, change your natural hair colour or highlight and streak certain portions for cosmetic purposes. At times, hair dyes can causes a severe allergy which is usually localised – only affecting the skin of the head. This is known as allergic contact dermatitis. In other instances, the use of a hair dye can have systemic effects – affecting the entire body. A systemic reaction to hair dye is not common but can be quite severe if it occurs.
What causes hair dye allergies?
Hair dyes contain a number of chemicals, some of which are quite strong and harsh. The main cause of hair dye allergies is a chemical known as paraphenylenediamine (PPD). The darker permanent hair dyes, usually those that are black in colour, tend to have paraphenylenediamine (PPD) to a larger degree than hair dyes of other colours. This chemical is less likely to be found in the same concentrations within temporary dyes or those of a lighter colour. However most hair dyes available in the market contain paraphenylenediamine (PPD).
Paraphenylenediamine (PPD) is a colourless chemical which changes when it becomes oxidised with other chemicals. You will find this when you use hair dyes which come in two bottles – one contains chemicals like paraphenylenediamine (PPD) while the other which is known as the oxidiser contains chemicals like hydrogen peroxide.
When the oxidiser is added, the paraphenylenediamine (PPD) becomes coloured and it is during this oxidation process that the most significant irritation can occur. Once the oxidation process is complete, the chemicals are less likely to cause any allergic reactions.
It is important to take note of the types of hair dye that you are using. Apart from paraphenylenediamine (PPD), other chemicals like isatin, p-methylaminophenol and 6-hydroxyindole may also cause hair dye allergies. These chemicals are present in most permanent hair dyes and if you have a sensitivity to it, then it is unlikely that you will be able to safely use these products.
Symptoms of a Hair Dye Allergy
Usually the allergy is isolated to the area upon which it is being applied. This may include the skin on the scalp, neck and forehead and extend to the ears or even the eyes. The symptoms may include :
- Burning, itching and pain.
- Redness of the skin.
- Dry, rough skin.
- Small vesicles (water-filled pimples).
The skin may remain red, painful or itchy for a few days and start peeling after a while.
If you have allergy-related conditions like eczema, you may notice an aggravation of symptoms. Some sensitive people report an aggravation of their asthma or hay fever as well but this could be attributed to other factors.
In some rare cases, anaphylactic shock may occur. This is a life threatening condition related to an allergy and immediate medical treatment is required.
Treatment or Prevention
Depending on the severity and extent of the allergic reaction, your doctor may prescribe an anti-histamine or a corticosteroid cream to reduce the symptoms. Anti-inflammatory drugs may be used if there is severe and persistent pain with other signs of inflammation.
If you are sensitive to hair dyes, then you should avoid it as far as possible. Speak to your dermatologist about other options for colouring your hair. In instances where the allergy is isolated to a portion of the skin where there is no hair, like the forehead or neck, you can apply a thick layer of petroleum jelly over the sensitive area before applying the hair dye.