Ingredient glossary / Colorant
PPD (p-phenylenediamine)
On the label: p-Phenylenediamine · Colorant
What it is
The dye base of most permanent dark hair colours and the main cause of hair-dye allergy; the EU requires a patch-test warning. Also the illegal additive in 'black henna' temporary tattoos.
Colorants: Colorants tint the product or the skin; in the US each is listed by its FDA name (CI number or D&C name).
Wikidata: Protein-coding gene in the species Homo sapiens. Q18038684 →
In the research
2,833 PubMed papers mention it with skin, cosmetics or hair; the three most recent:
- Adverse reactions associated with henna-based cosmetic products: a twenty-two-year pharmacovigilance analysis of the FDA adverse event reporting system · Cutaneous and ocular toxicology, 2026
- Textile-Integrated Electrochemical Sensing Approaches for Monitoring Wound-Relevant Biochemical Markers · International wound journal, 2026
- 60 years of sarcoidosis experience at an internal medicine clinic in Türkiye · Monaldi archives for chest disease = Archivio Monaldi per le malattie del torace, 2026
A paper is a paper, not a verdict: titles are listed so you can read them, and a study on cells or mice says little about a cream on a face.
Other colorants
Dew & Balm describes ingredients from the public record and makes no claim about what a product will do for you. Statements about dietary supplements have not been evaluated by the FDA. If a product causes a reaction, stop using it; a reaction that spreads or affects breathing is a call to a doctor or 911.