Zinc pyrithione was banned in EU cosmetic products from 1 March 2022. Four years of reformulation later, most “ZPT-free” claims are still built on the same three or four actives. Here is what the regulation changed, and where a cooling ester with in-vitro Malassezia data fits.
ZPT worked. It was cheap. It was in everything. The problem was that the substance was classified as a CMR 1B reproductive toxicant, and EU law prohibits CMR substances in cosmetics unless a narrow exemption applies.
| Date | Instrument | Effect |
|---|---|---|
| 2020 | (EU) 2020/1182 | ZPT classified as a CMR 1B substance (reproductive toxicity) under the CLP Regulation. |
| March 2020 | SCCS/1614/19 | Scientific opinion: 1% ZPT in rinse-off hair products is safe, but there is no evidence that no suitable alternative exists — so the CMR exemption cannot be used. |
| 3 November 2021 | (EU) 2021/1902 | Published. ZPT added to Annex II (prohibited substances); entries in Annex III (restricted) and Annex V (preservatives) deleted. |
| 22 November 2021 | — | Regulation enters into force. |
| 1 March 2022 | — | Applies. ZPT may no longer be used in cosmetic products placed on the EU market. |
| Unchanged | 21 CFR 358 / M032 | In the United States, pyrithione zinc remains an OTC monograph active: 0.3–2% in rinse-off and 0.1–0.25% in leave-on products for dandruff control. A product using it is an OTC drug, not a cosmetic. |
This table summarises public regulatory instruments. It is not legal advice, and it is not a statement about any finished product's compliance.
Each one changes what you can print on the pack, what testing you owe, and what the product costs.
Replace ZPT with another antimicrobial: piroctone olamine, climbazole, selenium disulfide, salicylic acid, or a combination. Closest to a like-for-like reformulation, and the route most brands took.
Check the current Annex III / Annex V entry for each candidate — limits differ by product type and by market, and they move.
In the United States you can still formulate ZPT as an OTC monograph active. That keeps the “controls dandruff” claim — and brings drug labelling, an NDC listing, drug establishment requirements and a completely different cost base.
A US-only route: the same formula carries a different claim in each market.
Formulate a cosmetic that delivers the sensory job the consumer actually notices — cooling, freshness, less itch perception, cleaner rinse — and support the scalp environment with mild surfactants and a pH that suits skin.
This is where a cooling ingredient belongs — a complementary route alongside the biocide system.
Menthol citrate ester is a mono-ester of L-menthol and citric acid. It is water-dispersible, stays in the formula instead of evaporating, and has published in-vitro inhibition data against Malassezia furfur. That combination makes it useful in the sensory-led route above, at a dose the label can carry.
All inhibition figures are in-vitro, generated on the ingredient or a simple vehicle. They are not clinical results and do not establish efficacy in a finished product. Full methods are in the technical dossier.
Both are reference starting points from our development work. Your surfactant system, preservation and fragrance will change the numbers.
| Parameter | Clear shampoo (rinse-off) | Scalp tonic (leave-on) |
|---|---|---|
| Use level | 1.0–3.0% w/w ester | 0.3–1.5% w/w ester |
| Grade | 10% sodium salt solution | 10% sodium salt solution or free acid with solubiliser |
| Contact window | 1–3 minutes — design the claim around it | Continuing exposure; lower dose is enough |
| Pair with | Mild surfactant system, panthenol, cationic polymer | PCA-zinc, niacinamide, glycerin, panthenol |
| Avoid | High-alkaline base, prolonged heat hold | Anionic thickeners at high dose, low-pH preservation mismatch |
Reference guidance for development. Compatibility, preservation and stability are confirmed on your own formula, and the final claims sit with your team.
Anti-dandruff products are cosmetics. The claim must be substantiated, the product needs a safety report and CPNP notification, and “antibacterial” language is treated as a biocidal-type claim that a cosmetic may not carry.
Naming and listing status is confirmed in writing for each destination, together with the records behind it. CosIng is an inventory rather than a positive list apart from colourants, preservatives and UV filters, and we send the file your safety assessor needs either way.
“Controls dandruff”, “helps prevent recurrence of flaking and itching” and similar wording make the product an OTC drug under monograph M032. A cosmetic may not carry those claims, whatever the active.
That means a US launch on the sensory route has to be positioned as a cosmetic scalp product: cooling, freshness, clean rinse. Keep the in-vitro data in the technical file, not on the front of the pack.
Send the brief: market, claim you want to make, and the surfactant system you are working with. We will tell you what the data supports.