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  • Rajani Katta MD

Do You Color Your Hair? This Is What You Need To Know About Hair Dye Allergy.

Updated: Aug 16, 2020


I'm seeing more and more patients who've become allergic to their hair dye. Many of these patients haven't been able to identify the trigger for their rash, but the awful red itchy patches on their face, eyelids, or neck are making them miserable. Do you think you're immune because you've been coloring your hair for years and have never had a problem? As I tell my patients, that doesn't mean a thing. Some of my patients have colored their hair for 20 or more years before they develop an allergy. Others develop an allergy soon after they start. Here's what you need to know about allergy to hair dye and how to prevent it:

1. If you're having your hair colored in a salon, make sure that they're careful. If you're doing it at home, make sure that you're careful!

Apply a layer of pure Vaseline petroleum jelly to your hairline, to act as a barrier so that no hair color touches the sensitive skin of your face. And don't let any of the hair dye solution land on your skin; I've seen allergic reactions show up on hands or forearms from a drop of solution.

2. The hair dye should be applied to your hair, not to your scalp. While this is standard practice at a hair salon, it may be harder for you if you're applying it yourself at home.

3. Follow the directions exactly. Leave on for the recommended time and no longer. Some of my friends tell me that they try to get other things done during this time, and they're not always watching the clock. Don't do this--this is one time where you want to follow the directions exactly.

4. Rinse thoroughly. I see reactions on the neck and upper back all the time, possibly because even a small amount of leftover active chemical can trigger a reaction.

5. Remember that all permanent hair color sold in the United States has the potential to trigger allergic reactions. This is due a chemical called p-phenylenediamine (PPDA). This chemical is found in almost all permanent, semipermanent, and demipermanent hair dyes, because it covers gray so well. However, it's the major trigger of allergic reactions to hair color.

Some people purchase "all-natural" hair color or "ammonia-free" hair color, thinking that it won't cause allergic reactions. While those types of hair color may be less irritating to the scalp, they're still likely to contain PPDA. 6. How do you know if you've developed an allergy? Surprisingly, hair dye allergy usually doesn't show up on the scalp. When allergic reactions occur, they often occur on the eyelids, on the forehead at the hairline, on the ears, on the neck, or on the shoulders. The scalp seems to resist allergic reactions better than surrounding areas. The thinner skin of the face and eyelids, on the other hand, is especially susceptible to allergic reactions. This allergy may show up as itchy red scaly patches, or it may show up as severe redness and swelling of the affected areas. Some patients have had such severe reactions that they've been hospitalized. 7. The most common type of allergic reaction to hair dye is allergic contact dermatitis, also known as delayed allergy. While the allergy may start the same day, it usually takes 2 to 3 days for the rash to begin. It can even take a week before the rash shows up. 8. Once the rash is there, it can last for weeks in some patients. While milder cases will eventually go away on their own, for more severe cases you should see your physician. The bottom line: hair dye is a chemical, and it has the potential to cause serious allergic reactions. Treat it and use it with respect.

Dr. Rajani Katta is the author of Glow: The Dermatologist's Guide to a Whole Foods Younger Skin Diet. To receive future updates on preventive dermatology and the role of diet, sign up here.

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