Colouring hair has become a norm today. Whether to add a bit of oomph factor to your looks or to cover greys in order to look ‘maintained’, hair dyes have found a place in almost everyone’s hair routine. Hair dyes come in a range of brands and labels to fit each type of pocket. For the typical conservative Indian mentality, they even come with tags like ‘natural’ and ‘ herbal’ and sometimes they even remove the stigma of the word dye and add replace it with the seemingly harmless term ‘henna or mehandi’. But do such tags make actually make them harmless? What constituents of hair dye cause allergy? What are the symptoms of hair dye allergy? Read on to find more….
What causes hair dye allergy?
Hair coloring products contain many ingredients that can irritate the skin and cause allergic reactions. In medical terms we call it allergic contact dermatitis. Most cases of allergic contact dermatitis to hair dye are caused by an ingredient called paraphenylenediamine (PPD) that procures the darkest tints and covers gray hair in a lasting manner. In boxed hair dyes, PPD usually comes in its own bottle, accompanied by an oxidizer. When both are mixed together, PPD becomes partially oxidised. This is when its likely to cause allergy. Most of the food and drug safety agencies recommend that the hair dyes should contain less than 2% of final PPD concentration when applied. Most of the good trusted brands abide by these guidelines, however, many local brands or the brands that mention themselves as ‘kaali mehandi’ contain much higher concentrations of PPD to the tune of 25%. Sadly, many of the temporary henna tattoo artists add a high concentration of PPD (~25%) to please their clients with a dark tattoo. Such high concentrations sometimes cause a severe, blistering, itchy allergic reaction to the henna tattoo or sensitizes the recipient to PPD who may now react to low concentrations of PPD in hair dyes, even if they would not have otherwise reacted.
It’s not always PPD that causes allergy. Some people also get allergy from ingredients such as ammonia, resorcinol, and peroxide. A patch test done in a dermatologist’s office can help identify which ingredient exactly is causing allergy.
What are the symptoms of hair dye allergy?
Signs and symptoms of hair dye allergy may begin immediately or take upto 48 hours to develop after hair dye application. The symptoms may range from mild to severe and include the following:
- stinging or burning sensation on the scalp, face, or neck that worsens on exposure to sun
- blisters or welts
- itching or swelling of the scalp and face
- swollen eyelids, lips, hands, or feet
- an angry, red rash anywhere on the body
- Anaphylaxis is rare but potentially fatal manifestation of hair dye allergy and manifests as swelling of the throat and tongue, troubled breathing, fainting, tummy pain, nausea, and vomiting
- Pigmented contact dermatitis is a less known complication of hair dye allergy among the masses but its not that uncommon. In this particular type of hair dye allergy one develops greyish pigmentation on face and neck especially along the hair line.
How to avoid hair dye allergy?
You can become allergic to hair dye at any time, even if you have been using the same brand for a number of years. That’s why, even if its a tried and trusted brand, one must do a patch test on a small area behind the ear and wait until it dries. Use vaseline all along the hairline to prevent hair dye from coming in contact with the facial skin. Also make sure:
- do not leave it on for longer than the recommended time
- wear gloves when applying the dye
- rinse your hair thoroughly afterwards
- carefully follow the instructions about mixing and preparing the hair colour
How to treat hair dye allergy?
Mild symptoms– In case of mild redness or itching, wash your scalp thoroughly with mild shampoo and apply moisturiser on the affected skin. Take an anti-allergic tablet like levocetrizine to relieve itching.
Moderate symptoms- In case of persistent symptoms or moderately severe symptoms, oral or topical steroids may be needed, and should be taken as prescribed by a dermatologist. One should definitely use physical sunscreen on face and other exposed areas in order to avoid exacerbation of symptoms.
Anaphylaxis– In case of anaphylaxis one should reach the hospital emergency immediately.
How to prevent recurrence of hair dye allergy?
First and foremost, avoid PPD containing hair dyes. If you develop a reaction to hair dye, even just a mild one, you should stop using products containing PPD altogether, as there’s a risk you could develop a more severe reaction in the future. Try switching to a safer alternative, such as a non-permanent, PPD-free hair dye,as suggested by your dermatologist- them – but be aware that it’s still possible to develop a reaction to PPD free hair dyes. Alternatively, you can dry henna leaves in the sun at home and grind and use them. It is important to note that once you have developed hair dye allergy you may also experience allergies from other dyes used for clothes and shoes, certain medications, anaesthetic agents, cough syrups and sunscreens that contain chemicals which cross react with PPD. So one must inform the treating doctor or hair dresser about PPD allergy.
Take home message: Hair dyes commonly cause allergies, most commonly due to the PPD in them. Check your brand and avoid using ones with PPD. One should also avoid getting black henna tattoos as they increase risks of developing hair dye allergy in future. Stay safe!
The author is a dermatologist and cosmetic surgeon practicing at Shalby Hospital, Mohali.