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Cosmetic ingredient

Zinc pyrithione

Former anti-dandruff staple — banned from cosmetics in Great Britain since October 2022 Also on labels as: pyrithione zinc, ZPT

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What it does

Zinc pyrithione (ZPT) was for decades one of the best-known anti-dandruff ingredients. Laboratory research suggests it works against Malassezia, the yeast linked to dandruff, in several ways — including raising zinc levels inside the yeast and interfering with how it makes energy.

You may still see it mentioned in older advice, including some dermatology leaflets, as an option for dandruff and seborrhoeic dermatitis.

Why you won't find it in UK shampoos now

ZPT was classified as toxic for reproduction (category 1B) under chemical-safety rules, which triggers a ban in cosmetics. In Great Britain it was added to the list of prohibited cosmetic ingredients from 15 October 2022, with existing stock allowed to be sold until 15 December 2022 (The Toys and Cosmetic Products (Restriction of Chemical Substances) Regulations 2022). The government's explanatory memorandum notes the same changes already applied in Northern Ireland, which follows EU rules — the EU had already banned it.

Cautions

  • Don't buy imported shampoos that list zinc pyrithione: in 2026 the Office for Product Safety and Standards rejected an imported anti-dandruff shampoo set containing ZPT at the border and had the listing removed from an online marketplace, rating the risk as serious.
  • Choose a UK-compliant alternative such as piroctone olamine, or a medicated shampoo with ketoconazole, coal tar or salicylic acid (NHS).

How strong is the evidence?

Evidence: Limited

Small or early studies only — promising at best.

Despite its long use, a 2015 BMJ Clinical Evidence review found only one small placebo-controlled trial and rated the evidence for ZPT in scalp seborrhoeic dermatitis as very low, concluding it shouldn't be a first-line treatment. Before the ban, the EU's scientific safety committee had judged it safe in rinse-off anti-dandruff products up to 1% — but its hazard classification meant it was banned anyway.

UK rules and availability

Prohibited in cosmetics in Great Britain since 15 October 2022 (Annex II entry 1669 of the GB Cosmetics Regulation). We found no UK-licensed medicine containing it.

Not medical advice. This guide is general information from the sources listed, not a diagnosis or a substitute for a pharmacist, GP or dermatologist. If you are worried, or symptoms are severe or not improving, get advice. Read our health information policy.

Sources

  1. The Toys and Cosmetic Products (Restriction of Chemical Substances) Regulations 2022 (S.I. 2022/659) legislation.gov.uk
  2. S.I. 2022/659 – Explanatory memorandum legislation.gov.uk
  3. legislation.gov.uk – Cosmetics Regulation Annex II (prohibited substances) legislation.gov.uk
  4. OPSS – Product safety report: anti-dandruff shampoo and conditioner set (2510-0132) gov.uk
  5. European Commission SCCS – Opinion on zinc pyrithione (2020) health.ec.europa.eu
  6. Park M et al. Mechanism of action of zinc pyrithione against Malassezia restricta. Sci Rep 2018 pubmed.ncbi.nlm.nih.gov
  7. Naldi L, Diphoorn J. Seborrhoeic dermatitis of the scalp. BMJ Clin Evid 2015 pmc.ncbi.nlm.nih.gov