Zinc Lactate
Genuinely relevant for some people, or depends on dose and pH.
What it is
Zinc lactate is the zinc salt of lactic acid, which the Cosmetic Ingredient Review records as soluble in its trihydrate form with an estimated log P of -2.97, and lists for use as a cosmetic astringent, cosmetic biocide, deodorant agent and oral care agent. It was one of the 27 zinc salts the Expert Panel assessed together and found safe as used, when formulated to be non-irritating. Its regulatory position is the interesting part, and it is genuinely unresolved. The salt is named nowhere in the Cosmetics Regulation - the string does not occur anywhere in the consolidated text. But Annex III entry 24 is not written as a list of names: its heading restricts "water-soluble zinc salts", and zinc lactate is plainly one of those. Which of those two facts governs is the question, and the regulation does not answer it.
How it shows up on a label
It sits in the middle stretch of every list here that carries it, never near the top - the position a salt used for its astringency usually takes.
What it does well
Reviewed by the expert panel and found safe as used
Zinc lactate was assessed among the 27 zinc salts the Cosmetic Ingredient Review Expert Panel reviewed together, and the Panel concluded that all 27 are safe in cosmetics in the present practices of use and concentration described in that assessment, when formulated to be non-irritating. The Panel's conclusion is about safety in use; it does not establish an effect on skin.
Moderate evidence
Worth knowing
Its EU status turns on a boundary the regulation never draws
Annex III entry 24 is written over "water-soluble zinc salts", and that phrase appears exactly once in the whole Cosmetics Regulation - in this entry's own heading. The regulation defines it nowhere, so there is no text that says how soluble a zinc salt has to be before the cap reaches it. For zinc lactate the solubility is not in doubt; what is in doubt is whether the heading or the list of six named salts beneath it sets the entry's scope. We record that as open rather than picking the answer that happens to be convenient.
Matters most toAnyone reading a panel that carries more than one zinc salt and assuming the same limit applies to each.
Very irritating to the eye as a neat powder, and slow to reverse
The Cosmetic Ingredient Review's eye testing puts this salt second-worst of the zinc salts examined, and the recovery is the part worth knowing. A tenth of a gram of solid zinc lactate powder - 0.027 g as zinc - was placed in the lower conjunctiva of three rabbits under OECD Test Guideline 405, left unrinsed, and followed for seven days. The report grades it very irritating: conjunctival damage had not completely reversed by day 7 in any of the three animals, severe corneal lesions had not completely reversed in two of them, and iris congestion and swelling were still present in two. In the summary sentence it sits between zinc nitrate, called irritating, and zinc sulfate, called severely irritating. On skin the same report finds the opposite - a four-hour occlusive patch of undiluted material was non-irritating to rabbit skin - so this is a mucous-membrane result rather than a skin one, and it comes from neat powder held in an eye rather than from a mask. It is still the reason to keep the product away from the eye.
Matters most toAnyone laying a sheet mask close to the eye area, or rinsing a wash-off mask near the eyes; contact-lens wearers in particular.
Where the EU stands
Class entry may apply
Not named in any annex, but arguably caught by a class entry. Annex III entry 24 restricts water-soluble zinc salts, and zinc lactate is one: the Cosmetic Ingredient Review records it as soluble. The entry's Common Ingredients Glossary column, however, names six salts - zinc acetate, zinc chloride, zinc gluconate, zinc glutamate, zinc citrate and zinc sulphate - and zinc lactate is not among them. Those two columns, "Chemical name/INN" and "Name of Common Ingredients Glossary", sit under one shared heading, "Substance identification", so both are identification and they disagree here. One sign that the class heading is doing the work: the entry troubles to except zinc 4-hydroxy-benzene sulphonate, which is itself not one of the six named salts - an exception is only needed for something the rule would otherwise catch. On that reading zinc lactate is capped at 1% (as zinc) in products other than oral care, with compliance biting from 1 January 2027 for placing on the market and 1 July 2028 for making available. On the narrower reading nothing attaches. No primary source settles which column governs and the regulation never defines "water-soluble", so we record the position as unsettled rather than assert a restriction no source establishes.
Regulation (EC) No 1223/2009, Annex III entry 24 (water-soluble zinc salts), as replaced by Regulation (EU) 2026/909 - reached by the column b class heading, absent from the column c glossary list · source ↗
Sources (2)
Every link goes to the original: a journal, a PubMed record or an EU document.
- [1]Safety Assessment of Zinc Salts as Used in Cosmetics
Cosmetic Ingredient Review Expert Panel, Final Report · 2018
Zinc Lactate is one of the 27 zinc salts concluded "safe in cosmetics in the present practices of use and concentration described in this safety assessment when formulated to be non-irritating". The report defines it as "the zinc salt of lactic acid", CAS 16039-53-5 and 554-05-2, functioning as a cosmetic astringent, cosmetic biocide, deodorant agent and oral care agent, with water solubility "Soluble (trihydrate)", formula weight 243.52 and an estimated log P of -2.97. Its irritation record splits by tissue: a four-hour occlusive patch of the undiluted material was non-irritating to rabbit skin, but in the eye "Zinc Lactate (undiluted powder) was very irritating" - 0.1 g of solid powder (0.027 g as zinc) instilled into three rabbits' eyes under OECD TG 405 and left unrinsed, with conjunctival damage "not completely reversible by 7 days in all 3 animals", severe corneal lesions not completely reversible in two, and iris congestion and chemosis not fully reversible in two. The same report describes the then-current Annex III entry 24 as restricting "water-soluble zinc salts (Zinc Acetate, Zinc Chloride, Zinc Gluconate, and Zinc Glutamate) with the exception of zinc 4-hydroxybenzenesulphonate (entry 25) and zinc pyrithione (entry 101 and Annex V, entry 8) to a maximum of 1%" - two carve-outs, neither of them among the named salts. Checked 4 October 2026.
- [2]Regulation (EC) No 1223/2009 on cosmetic products, consolidated text 02009R1223 - EN - 18.05.2026 - 041.001
EUR-Lex, Official Journal of the European Union · 2026
Searched in full for this entry: "Zinc Lactate" occurs nowhere in the consolidated text, and the phrase "water-soluble" occurs exactly once - in the heading of Annex III entry 24 itself, which is therefore the only place the class is described and nowhere defined. Annex III's columns b to e sit under the shared heading "Substance identification" and are "Chemical name/INN", "Name of Common Ingredients Glossary", "CAS number" and "EC number". Checked 4 October 2026.
