What Is Hydroxyacetophenone, and Is It Safe?
You bought the moisturizer because the front of the bottle said clean. Then you turned it over, ran your eye down the ingredient list, and hit hydroxyacetophenone. Nineteen letters. Sounds like something with a hazard symbol on the drum.
Here’s the short version, because you probably came here for it and not for a chemistry lecture: this one’s fine. The US safety panel reviewed it in 2022 and called it safe at the levels currently used, which usually means well under 1%. EWG scores it 1, the lowest hazard rating it gives. It’s one of the more reassuring things you’ll find on a skincare label, and the safety review behind it is unusually thorough for an ingredient most people have never heard of.
But it’s worth understanding why it’s in there, because the reason is more interesting than the ingredient.
The job it’s doing in your moisturizer
Hydroxyacetophenone has two jobs on paper and a third in practice.
The Cosmetic Ingredient Review, the industry-funded but independently staffed panel that assesses ingredients for the US market, lists it as an antioxidant and a skin-conditioning agent. Antioxidant means it slows the oxidation that turns oils rancid and makes a cream go off. Skin conditioning is the vaguer one: it helps the product feel decent on your face.
The third job is the one formulators actually buy it for. It’s a preservative booster. On its own it won’t keep a water-based cream sterile, but paired with a real preservative it makes that preservative work harder, which lets a brand use less of it.
That’s the whole commercial logic. If you want a product that survives a year in a warm bathroom without leaning heavily on the preservatives people have learned to fear, something has to pick up the slack.
What the safety review found
The CIR panel published its assessment in 2022 and concluded that hydroxyacetophenone is safe in cosmetics at the levels currently used.
Four things persuaded them, and the first is the one I’d lead with at a dinner party: it’s already a food flavoring. Hydroxyacetophenone holds FEMA GRAS status, meaning a panel of experts has cleared it as generally recognized as safe to eat. You’re worried about it touching your face. It’s been going in your mouth for years.
The rest of the case is duller and more convincing. A 28-day feeding study in rats found no toxicologically significant changes at doses up to 600 mg per kilogram of body weight per day, which became the no-observed-adverse-effect level. The material used in cosmetics comes in at 99.5% purity, so there’s very little else riding along. And its chemical structure carries none of the flags that make toxicologists nervous.
How much ends up in your products? Not much. Symrise, which sells the best-known version, tells formulators to dose it at up to 1%. The industry survey behind the review reported a top-end 5% in leave-on night products and masks, 0.6% in bath products, and 0.23% around the eyes. So the usual answer is a fraction of a percent.
So why does EWG restrict it?
Here’s where it gets a little tricky, and where most articles on this ingredient just stop.
The Environmental Working Group’s Skin Deep database scores hydroxyacetophenone a 1, its lowest hazard rating, with a data availability rating of “Good”. Cancer: low. Allergies and immunotoxicity: low. Developmental and reproductive toxicity: low. About as clean a card as an ingredient gets from an organization not famous for handing them out.
And yet EWG’s own certification program lists it as restricted, meaning an EWG VERIFIED product can’t contain it without adequate substantiation.
Those two things look contradictory. They aren’t, quite. A hazard score answers “is this substance harmful?” A certification restriction answers “will we take your word for how you’re using it?” EWG’s mark is a promise about a specific finished product, so it asks brands to show their work on ingredients where the answer depends on the details. That’s a paperwork bar, not a safety verdict.
Worth knowing if you shop by the EWG VERIFIED seal and wonder why a product you liked doesn’t carry it. It might not mean what you assumed.
Where I’d spend the worry instead
| Quick facts | Hydroxyacetophenone |
|---|---|
| Also written | 4-hydroxyacetophenone, or piceol |
| What it does | Antioxidant and preservative booster. It doesn’t preserve on its own |
| Supplier dosage | Up to 1%, though the industry survey reported 5% at the top end |
| Safety review | Cosmetic Ingredient Review, 2022, safe at current levels |
| EWG score | 1, the lowest, with data availability rated good |
| EU status | Not restricted at all, unlike phenoxyethanol’s 1% cap |
| Allergy record | Five published case reports, three of them after the 2022 review |
| Also cleared as | A food flavoring, under FEMA GRAS |
Nothing. I wouldn’t put this on an avoid list, and I wouldn’t pay extra to dodge it.
If you’re going to spend your limited label-reading energy somewhere, spend it on undisclosed “fragrance,” which can hide dozens of undeclared ingredients including phthalates, or on the preservatives with real allergy data behind them. Hydroxyacetophenone isn’t where the risk lives. It’s a mild antioxidant that lets brands use less of the ingredients you were probably trying to avoid in the first place.
The one thing the safety review couldn’t have known
Here’s the part I’d want told to me, and almost nobody covers it.
Dermatology journals have now published five case reports of allergic contact dermatitis traced to hydroxyacetophenone. The first, in 2018, was a 79-year-old man whose eyelid dermatitis cleared once he stopped the face cream causing it, confirmed by a patch test at 0.6%. Three of the other four were published in 2023, 2025 and 2026, which is to say after the CIR panel closed its review in 2022.
Keep the scale in mind. Five reports against 791 products on the US market and years of mass-market use is a rare-event signal, not a scandal, and it’s roughly what you’d expect from any ingredient that gets popular enough. It doesn’t change the verdict for almost everyone reading this.
What it does change is the tidy version of the story. This ingredient sits in an odd spot: cleared by the US panel, scored 1 by EWG, and not restricted by the EU in any way, while a small allergy literature builds quietly underneath. If you have stubborn eyelid or facial dermatitis that you’ve never explained, and your products contain it, this is now a reasonable thing to raise with a dermatologist and ask to be patch tested for.
“Safe at the levels currently used” is a statement about today’s products and today’s evidence. It’s the strongest thing a review panel can say, and it isn’t the same as “studied for forty years in humans.” Very few cosmetic ingredients clear that bar. This one clears every bar we currently have, and the case reports are the honest asterisk.
Frequently asked questions
Is hydroxyacetophenone a preservative?
Not on its own. It’s an antioxidant and skin-conditioning agent that works as a preservative booster, making the actual preservative in the formula more effective so a brand can use less of it. A product relying on hydroxyacetophenone alone wouldn’t stay safe to use for long.
Is hydroxyacetophenone natural or synthetic?
The version in your skincare is made in a lab, but the molecule itself is a plant one. It’s called piceol in botany, and Norway spruce needles carry it at roughly 0.4% to 1.1% of their dry weight, where it appears to be part of how the tree handles stress. Your skin can’t tell the difference between the two, and the lab version comes with a purity level (99.5%) no plant extract will match.
Can hydroxyacetophenone irritate sensitive skin?
It’s rated low for irritation and low for allergy risk, and for most people it’s a non-event. There are five published case reports of genuine contact allergy to it, mostly involving the face and eyelids, so it isn’t impossible. It’s just rare. If a product with it in there stings, the likelier culprits are acids, essential oils, undisclosed fragrance, or a preservative like caprylhydroxamic acid, which has a much heavier allergy record.
Why is it in “preservative-free” products?
Because technically it isn’t a preservative, some brands use it in systems they market that way. Read that claim carefully. A water-based product with nothing antimicrobial in it at all would grow mold, so “preservative-free” usually means “preserved with something we’d rather not call a preservative.” That’s a marketing choice, not a safety problem.
Related reading
If you’re reading labels this closely, our guide to the skincare ingredients worth avoiding covers the ones that actually earn the worry, and our explainer on endocrine disruptors in cosmetics gets into the science of why some of them matter. For brands whose labels we’ve already been through line by line, start with the best non-toxic skincare brands or browse the scored profiles in our brand directory. Same series, other labels: butylene glycol, PEG-100 stearate, potassium sorbate, and benzalkonium chloride, the one we do steer you away from.
Sources: Cosmetic Ingredient Review, Safety Assessment of Hydroxyacetophenone as Used in Cosmetics (2022). Environmental Working Group, Skin Deep entry for hydroxyacetophenone. Sanz-Sánchez T, Valverde Garrido R, Maldonado Cid P, Díaz-Díaz RM, Allergic contact dermatitis caused by hydroxyacetophenone, Contact Dermatitis 2018;78(2):174-175. Gatica-Ortega ME, et al., Allergic contact dermatitis caused by hydroxyacetophenone in an anti-wrinkle serum, Contact Dermatitis 2023;88(5):407-409. Pesqué D, et al., Photo-aggravated allergic contact dermatitis caused by hydroxyacetophenone, Contact Dermatitis 2025;93(5):415-417.
