p-Phenylenediamine (PPD)

Also known as: PPD, paraphenylenediamine, p-phenylenediamine

Moderate concernunder our published method

By NordicScan Evidence Engine · generated from structured evidence records · source spans verified by automated gates · Reviewed 2026-07-08 · Evidence snapshot geo-wave1-evidence-snapshot-2026-07-08 · Scoring engine det_v3 · how we score.

What it is

p-Phenylenediamine is a coal-tar hair-dye ingredient used in some permanent and dark hair-colour products.

Why people ask

People ask because hair-dye rules, patch-test instructions and ingredient-reaction reports are often discussed together.

What our method flags — by use

Cosmetic · US hair dyes

In US hair-dye scope, our method rates PPD as moderate-concern because FDA flags it in the hair-dye reaction discussion.

The US FDA flagged by hair-dyes page PPD as a hair-dye ingredient implicated more prominently in allergic reactions and cross-sensitization examples.

Authority / source	Finding (our paraphrase)	Evidence tier	Date	Link
US FDA	The US FDA flagged by hair-dyes page PPD as a hair-dye ingredient implicated more prominently in allergic reactions and cross-sensitization examples.	authority_regulatory	2025-09-25	source

Evidence coverage for this use: Limited (computed from source count × authority tier × recency; signals depth, does not change the concern band).

How this moves a product’s score

On a product score, PPD contributes a moderate concern signal in hair-dye scope from the FDA hair-dye evidence cell.

Nordic Scan provides ingredient information and a concern score under our published method, for general consumer research. It is not medical advice and not a medical device, and does not diagnose, treat, cure, or prevent any disease, or determine the safety of any product. Decide for yourself.

This is what p-Phenylenediamine (PPD) is. What’s in the products you buy? Scan a label and see the concern signals our method flags. Get the app.

Reviewed 2026-07-08 · Evidence snapshot geo-wave1-evidence-snapshot-2026-07-08 · Scoring engine det_v3 · Sources checked 2026-07-08 · See how we score.