Hair Dye Allergy!
In the quest for looking young, the prevalence of hair dye reactions have increased in recent years as dyeing hair has become popular among people of all ages. Allergy is more common in people who colour hair regularly, hair dressers, photographers and those who use black temporary tattoos.
The molecules in hair dye are para-phenylenediamine(PPD), para-toluenediamine(PTDS), para-aminophenol and hydrogen peroxide. Most reactions to hair dye and henna/kaalimehendi  are due to PPD. Ammonia which is often blamed as the culprit only facilitates in dye penetration into the inner layers of hairshaft (cortex). In ammonia-free hair dye, this is performed by sodium carbonate and ethanolamine. Hence ammonia-free dye do not prevent allergy.
The symptoms may begin within a few hours to 1-2 days after the application of the dye with itching, redness, swelling, blisters, over the scalp, hairline, face, neck, chest, arms, beard and moustache.
People who use hair dye should not keep the dye in the hair for longer than the recommended time. It should be washed out thoroughly. While applying dye, wear neoprene hand glove , hair colouring cap with holes and apply petroleum jelly or dimethicone cream to the skin adjacent to the hairline to avoid dye spillage on skin .
Always perform a patch test by applying dye with a cotton swab  behind ear or forearm and allowed to dry. The dye can be safely used If  no reaction in 48 to 72 hours. Negative result to patch test does not guarantee freedom from reaction as patch test itself could cause sensitisation and result in rash the next time the hair is dyed.

Studies have shown increased risk for bladder cancer, asthma etc among hairdressers. Recommendations for female hairdressers include working for less than 35 hours per week.
Dye containing PTDS may be an alternative for those allergic to PPD. Safest is use of pure home ground henna.
Immediately Consult a Dermatologist if you develop any discomfort after applying hair dye.

Dr.ANJANA MOHAN  MD-DVL ,Fellow in Derm laser surgery
Consultant  Dermatologist, Skinsecrets clinic, Cochin, Kerala.
Ph : (+91) 7025066555.

Authored By: Dr.Anjana Mohan