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Diethanolamine

Red flag

Evidence key Strong Moderate Weak How we grade

Banned in EU cosmetics Possible carcinogen Chemical of concern

What it can be used for
Keeps the pH steady (the functions the EU ingredient database, CosIng, lists for it; a product may use it for any of them)
CAS number
111-42-2

Why it’s flagged

  • Prohibited in cosmetics in the EU.

    Annex II of the EU Cosmetics Regulation lists substances that must not be used in cosmetics sold in the EU.

  • Classified as a possible or suspected human carcinogen.

    IARC Group 2B means possibly carcinogenic to humans. EU Carc. 2 means suspected human carcinogen. These describe a hazard, not the risk at the amount in one product.

  • Listed as a chemical of concern by the Campaign for Safe Cosmetics.

    The Campaign for Safe Cosmetics is an advocacy group. Its profiles explain why it considers these ingredients a concern.

What the research says

  • Two no-lye hair relaxer kits marketed for children had the highest measured levels of chemicals banned in EU cosmetics or listed under California's Proposition 65 (DEHP, nonylphenol, o-phenylphenol, diethanolamine) of any products tested in this study. Moderate evidence. Helm 2018

About ingredients flagged like this one:

  • The EU bans more than 1,400 substances from cosmetics, while US rules restrict only a handful. Moderate evidence. Alblooshi 2025

Each finding shows its evidence grade. See every graded fact or how we grade.

What this page can’t tell you

These lists describe what a substance can do, its hazard. The risk from one product depends on how much is in it and how you use it, and the label doesn’t say how much.

Not being on a list doesn’t make an ingredient safe. It may never have been assessed.

Check your products

Check a whole labelProducts that list itEWG Skin DeepShop fragrance-free

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Flagged the same way

Official lists checked September 2026. Spotted a mistake? Tell us.