CosmeticBet
Anti-dandruff actives

Zinc pyrithione

INCI: ZINC PYRITHIONE · also ZPT, Pyrithione zinc

A proven dandruff fighter: a drug ingredient in the US, banned in EU cosmetics since 2022.

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C10H8N2O2S2Zn317.70 g/mol
zincsulfuroxygennitrogencarbon
2D drawing from PubChem 26041 (hydrogens hidden)

How common

All products0.71%
In shampoos7.6%
In conditioners6.7%

105 of 14,784 products with a full ingredient list in Open Beauty Facts; No. 338 of all the names found on their labels.

What it is

  • A zinc compound active against Malassezia, the yeasts believed to play a major role in dandruff.

    SourceHide
    Ketoconazole (KET) and zinc pyrithione (ZPT) are compounds active against the Malassezia spp. yeasts, which are believed to play a major role in dandruff and seborrheic dermatitis.[1] Study · 2002 · open source

Why it is in products

  • Against dandruff.

    SourceHide
    (2) Pyrithione zinc, 0.3 to 2 percent when formulated to be applied and then washed off after brief exposure.[2] US federal regulation · 2024 · open source

What it does

  • In a half-head trial, the side washed with a 1% zinc pyrithione shampoo had steadily less dandruff than the side washed with the same shampoo without it.

    Good evidencescalpSourceHide
    There was a progressive reduction in dandruff on the sides of the head treated with the ZPT shampoo, the differences relative to the placebo-treated areas being statistically significant after three, six and nine washes.[3] Study · 1985 · open source

  • In an independent trial of 331 people with severe dandruff, ketoconazole 2% did better than zinc pyrithione 1%, and dandruff came back less often after it.

    Good evidencescalp3 sourcesHide
    KET 2% shampoo was significantly superior to ZPT 1% shampoo in the treatment of subjects with severe dandruff or seborrheic dermatitis of the scalp[1] Study · 2002 · open source
    Of the 331 eligible volunteers[1] Study · 2002 · open source
    The recurrence rate of the disease was also significantly lower following KET 2% treatment than following ZPT 1% treatment.[1] Study · 2002 · open source

Downsides and safety

  • The EU classifies it as toxic for reproduction (category 1B). EU scientists found it safe at up to 1% in rinse-off anti-dandruff products, but it was banned from cosmetics from 1 March 2022, because it had not been shown that no suitable alternatives exist.

    Well established4 sourcesHide
    which has been classified as a CMR substance of category 1B (Toxic for Reproduction)[4] EU law · 2021 · open source
    Zinc Pyrithione can be considered safe when used as an anti-dandruff ingredient in rinse-off hair products up to a maximum concentration of 1 %[4] EU law · 2021 · open source
    since it has not been established that there are no suitable alternative substances available with regard to anti-dandruff ingredients in rinse-off hair products[4] EU law · 2021 · open source
    It shall apply from 1 March 2022.[4] EU law · 2021 · open source

  • A dandruff review notes irritation in about 3% of users.

    Some evidenceSourceHide
    Zinc Pyrithione 1% shampoo Scalp: 2–3 times/week. Increased cellular copper interferes with iron-sulfur proteins. ICD in ~3% of patients.[5] Study · 2015 · open source

Where it works

SurfaceOuter layer(stratum corneum)Living layer(epidermis)Dermis

On the scalp, against the yeasts linked to dandruff.

Good evidenceSourceHide
are compounds active against the Malassezia spp. yeasts[1] Study · 2002 · open source

Rules

European Union

  • Banned in cosmetics since 1 March 2022 (Annex II, entry 1670).

    2 sourcesHide
    1670 Pyrithione zinc; (T-4)- bis[1-(hydroxy-.kappa.O)pyridine-2(1H)- thionato-.kappa.S]zinc[6] EU law · 2026 · open source
    It should also be added to the list of substances prohibited in cosmetic products in Annex II[4] EU law · 2021 · open source

United States

  • An over-the-counter dandruff drug ingredient: 0.3 to 2% in products washed off, 0.1 to 0.25% in products left on.

    2 sourcesHide
    (2) Pyrithione zinc, 0.3 to 2 percent when formulated to be applied and then washed off after brief exposure.[2] US federal regulation · 2024 · open source
    (3) Pyrithione zinc, 0.1 to 0.25 percent when formulated to be applied and left on the skin or scalp.[2] US federal regulation · 2024 · open source

Sources

  1. A multicenter randomized trial of ketoconazole 2% and zinc pyrithione 1% shampoos in severe dandruff and seborrheic dermatitis Piérard-Franchimont C et al., Skin pharmacology and applied skin physiology, 2002Study
  2. 21 CFR Part 358: Miscellaneous external drug products for over-the-counter human use, incl. dandruff, seborrheic dermatitis and psoriasis (2024 edition) US Government Publishing Office (govinfo), Code of Federal Regulations, 2024US federal regulation
  3. The effects of a shampoo containing zinc pyrithione on the control of dandruff Marks R et al., The British journal of dermatology, 1985Study
  4. Commission Regulation (EU) 2021/1902 amending Annexes II, III and V to Regulation (EC) No 1223/2009 as regards the use in cosmetic products of certain substances classified as CMR Official Journal of the European Union, 2021EU law
  5. Seborrheic Dermatitis and Dandruff: A Comprehensive Review Journal of clinical and investigative dermatology, 2015Study
  6. Regulation (EC) No 1223/2009 on cosmetic products, consolidated text of 18 May 2026 Publications Office of the European Union (EUR-Lex/Cellar), 2026EU law

Checked against these sources on 4 November 2026. Spot a mistake? Tell us.