Para-phenylenediamine is an azo dye, most commonly used in permanent hair dyes as a black dye. It is also used in black rubbers, photographic developers, fabric dyes, epoxy resin curing agents, oils and greases, and gasoline. Potential cross-reactions include preservatives of the paraben family, para-aminobenzoic acid, sulfonamides (including diuretics and diabetes agents), and benzoic acid ester group anesthetics. Even if the hair product is "PPD free", other phenylenediamine variants may cause reactions.
Pure, uncontaminated Lawsonia inermis (henna tree) should not cause reactions in PPD-allergic patients and may be a reasonable alternative as a hair dye. Pure henna is an extremely rare cause of allergic contact dermatitis (ACD).
The vast majority of reactions to hair-dye products are caused by para-phenylenediamine (PPD). As of 2019, PPD has been used in most permanent, demipermanent, and semipermanent hair-dye products. PPD was the contact allergen of the year in 2006.
Some manufacturers produce permanent and demipermanent dyes using para-toluenediamine sulfate (PTDS) instead of PPD (see below), 57% of patients allergic to PPD will tolerate hair dyes based on PTDS.
Practical recommendations for 3 patch tests:
1. TRUE patch test. Test for PPD with TRUE patch test.
2. Hair dye series patch test. If contact allergy to PPD is confirmed: test with a complete hair dye series. If that series is unavailable, at least do a patch test for PTDS. Patients who are allergic to PPD but test negative for allergy to PTDS will very likely tolerate the PPD-free hair-dyes based on PTDS.
3. Specific hair dye patch test. Although patients who are patch test negative to PTDS will likely tolerate the PTDS-based hair-dyes, the recommendation is to do a patch-test for any proposed PTDS-based hair dye. If the test is negative, then use the product.
In patients allergic to hair dye: do not use a hair dye without a patch test.
Alternative to PPD-hair dyes
PPD-Free Hair Dyes Based on PTDS:
- Wella Koleston Perfect (permanent), Wella Color Charm (demipermanent) - The Wella Corporation, Richimond, VA
- Schwarzkopf Igora Royal (permanent) - Schwarzkopf & Dep, Rancho Dominguez, CA
- Goldwell Color Chic (permanent), Goldwell ReShade for Men (demipermanent)
- Sanotint Light (demipermanent) - Sanotint, Cosval Arese, Italy, PSS, Iinthicum Heights, MD
- L'Oréal Paris Excellence To-Go 10-Minute Cre`me Colorant (demipermanent) - IL'Oreal USA Inc, Clark, NJ
Pure henna is an alternative hair dye. Uncontaminated Lawsonia inermis (henna tree) is an extremely rare cause of allergic contact dermatitis (ACD).
In PPD-allergic patients, cross-reactions may occur with other chemicals such blue disperse clothing dyes. Cross-reactions have also been reported to para-aminobenzoic acid-containing sunscreens and topical sulfonamides.
Hair dye-induced allergic contact dermatitis (click here to enlarge the image).