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Baylor College of Medicine News

Allergic reactions to hair dye can happen at any time

Dyeing hair seems to come naturally to many people as they age, but it could be the cause of an allergic reaction, no matter how long you've been using the same product, according to a dermatologist at Baylor College of Medicine.

"You can develop an allergy to a product at any point in time," said Dr. Rajani Katta, professor of dermatology at BCM. "One allergic reaction we're seeing commonly is to hair dyes."

The symptoms of hair dye allergies aren't necessarily immediate, she said. They can occur two, three or even up to seven days after exposure to the product.

Check list of ingredients

Symptoms include redness of skin and itching on the hairline, face, eyelids, ears, neck and even back. The main culprit of thisreaction is a chemical called p-phenylenediamine, also known as PPDA. This is the best chemical to cover the greys, so it's found commonly in hair dyes. Katta suggests that rather than checking for products that are "ammonia free" or "all-natural," look to see if the dye has PPDA – it's usually found midway in the list of ingredients.

"It may start as a mild reaction, but it can get worse over time and spread to other parts of the body," said Katta.

For a mild reaction, she suggests applying over-the-counter hydrocortisone cream to the affected areas. If the hydrocortisone is not helping after one week, see a dermatologist.

If the dermatologist is unsure of the cause of the allergy, they may do patch testing, which is different than prick testing. Prick testing is done by allergists to check for reactions to pollen and other allergens that cause symptoms such as hay fever, sneezing and coughing. Patch testing is done by dermatologists and some allergists to check for skin rashes caused by various chemicals and products.

Hair coloring options

For those who develop an allergy to PPDA, Katta suggests avoiding any product that has this chemical. While there are a few hair dyes that don't contain PPDA, they can be difficult to find. Katta suggests some other hair-dyeing solutions:

Henna – a natural product that's been used in India for hundreds of years and gives a reddish color to the hair. Be sure you are buying pure henna, and avoid a newer product called black henna, which may have added PPDA.

Highlights – these are bleaching agents that don't usually contain PPDA.

Temporary hair rinses.

Lead oxide dyes that darken gray hair – check the ingredients carefully as the same brand name can also sell products with PPDA.

Find a salon that is familiar with hair dye allergies – there are some salon products available that don't contain PPDA.

There are other ingredients related to PPDA that may also cause a similar reaction, so Katta suggests that if you're allergic to PPDA, get tested by a dermatologist to see if you're also allergic to similar ingredients.