After fragrances and preservatives, paraphenelyendiamine (PPD) is the substance most likely to cause an allergic reaction.
So, what is it?
PPD is a chemical often used in salon and store-bought hair dyes to achieve natural looking shades that don’t fade with shampooing. With the help of ammonia, PPD reacts with the air and deposits pigment inside the hair shaft at the cortex — a process that creates more long-lasting results than plant-based or semi-permanent dyes that only colour the outside of the hair.
Unfortunately, the cosmetic effects of PPD can come at a price for many people. Allergies ranging from mild (a rash on the top of the ears and eyelids) to severe (swollen eyes and face) have been reported. PPD has even been known to cause anaphylaxis in some extreme cases.
In my own experience, patients have come to my office complaining of mild redness, burning and stinging after applying hair dye. And while these reactions are frequently determined not to be allergic, they can become more severe if chemicals are left on too long or used too frequently. In these patients, I usually recommend pre-treating the scalp with a prescription steroid lotion.
If you are allergic to PPD, don’t despair.
PPD-free hair dyes do exist, you just have to do your homework to find them (or see my list below if you want to cheat). It’s complicated chemistry but you need to use hair dyes that contain a related substance known as para-toluenediamine sulphate (PTDS). Only 25 percent of people allergic to PPD will react to PTDS.
As always, it is imperative to read the full ingredients’ list since hair dyes advertised as ‘natural ‘ may still contain chemicals like PPD or its sneaky allies.
Here are some other chemical names that are related to PPD and will casuse a reaction if you are allergic to PPD
PPD-FREE HAIR DYES