The majority of hair colorant users will never develop an allergy because it is not in their genes to be susceptible; it's all in the genes. Fifty million units of home hair colorants are sold and forty-five million salon applications of hair colorants are carried out in the UK each year and adverse reactions are exceedingly rare - far rarer than food allergies. European figures show that the incidence of marked or severe allergic reaction to hair colorants is approximately three in every million units.
When reactions to hair colorants do occur, their effects are short-term but can be very uncomfortable, so it is important to make sure you use your hair colorant safely to avoid an adverse reaction. Always read and follow the instructions and carry out an allergy alert test each time you use a product, even if it is the same brand you always use as sensitivity can develop with repeated use. If you do suffer a reaction following the use of a hair colorant, you should contact your doctor first but also contact the manufacturer of the product or the salon where you had your hair coloured, both of whom will help you and your doctor handle your reaction.
Allergic reactions are themselves rare, however in a severe allergic response hair loss might follow. This is an extremely rare reaction. If, in exceptional circumstances, hair loss does occur, this should be temporary and help will be available from the manufacturer or the salon. They may suggest you visit a specialist e.g. a trichologist or dermatologist.
Important safety instructions are provided on the outer pack and on instruction leaflets contained inside hair colorants. These warnings alert us to the possibility of allergic reactions and that these reactions, although rare, may be severe. The instructions emphasise an Allergy Alert Test must be carried out.
How to do the 48 hour Allergy Alert Test
Different manufacturers and salons may recommend slightly different ways of doing the test based on their experience with a particular method, but also because of varying product formulations, packaging and applications.
The basic principle however is common and clear instructions are provided:
the instructions must be followed exactly each time;
the Allergy Alert Test must be carried out each and every time you colour your hair as sensitivity can develop with repeated use;
use a small amount of the hair colorant of choice at a small skin site, as directed, 48hrs before using the product;
if you react to the Allergy Alert Test, do not go-ahead and colour your hair.
The test can be inconvenient but we are constrained by biology; the delayed contact allergy reaction takes up to 48 hours to develop. If you cut corners, you risk missing a positive reaction. The test is the best available, tailored to each of the many different products on the market. Independently reviewed research shows that allergy alert testing is highly effective when carried out as instructed.
You do not need to buy a second pack just for the purpose of the test. Just re-close the packs after taking out the small amount recommended for the test.
What should I do if I react to an allergy alert test?
If you react to the allergy alert test, do not go ahead and colour your hair, even with a product you may have used before. Contact the manufacturer (careline or helpline numbers are provided on the pack). If you have reacted to the allergy alert test, the company will help you and your doctor organise diagnostic patch-testing with a dermatologist. This will identify which ingredient led to the reaction. You must not use any product containing that ingredient in future, even from another manufacturer.
Because of the possibility that people who react to the hair dye paraphenylene diamine (PPD) could react to other, similar, hair dyes, all the products with dyes in this family will be labelled 'contains phenylene diamines'.