Silicones in Hair Products: What the EU Restricted

Europe restricted a group of silicones in rinse-off products in January 2020, and almost nobody noticed. This June the rules widened again, and from June 2027 they reach leave-on products too.

The restriction covers D4, D5 and D6, the cyclic silicones, and the reasoning has nothing to do with what they do to hair. Regulators classified them as very persistent and very bioaccumulative. They don’t break down, and they build up in living things.

The Commission’s own estimate is that the rules cut emissions of these chemicals by up to 90%.

So the silicone conversation has two halves that keep getting mashed together, and separating them is most of the work here.

Half one: what silicones do to your hair

Not much harm, honestly.

A silicone coats the hair shaft. That coating smooths the cuticle, adds slip so a comb glides through, cuts frizz and makes hair shine. It works, which is why it’s in so many conditioners and nearly every serum sold on the promise of glossy hair.

The knock on them is build-up: the coating accumulates, weighs hair down, and blocks moisture from getting in, so hair ends up looking dull and feeling coated. That’s the complaint behind most “silicone-free” marketing.

It’s real, and it’s smaller than the marketing implies. The silicones that really do rinse away are the ones grafted onto water-loving chains, which you spot by the prefixes PEG- and PPG-. Ignore the advice that names ending in “-conol” are water-soluble, because dimethiconol isn’t; it’s the same insoluble backbone with a different end on it.

What the measurements actually show is that deposition levels off rather than piling up forever. When researchers treated hair once, three times and five times, the amount stuck to the hair was the same after one treatment as after five. Ordinary shampoo then took roughly half of it back off. There is no published data at all on twenty or fifty washes, so anyone describing indefinite accumulation is extrapolating past the evidence.

Whether it accumulates at all turns out to depend on the rest of the formula rather than the silicone: with a cationic conditioning polymer in the mix, deposition stays flat.

That’s the actual trap, and it catches people who did everything right. Switch to a mild sulfate-free shampoo while keeping a silicone-heavy conditioner, and you get build-up you didn’t have before, because the gentle cleanser can’t strip what the old one did. Then you blame the clean shampoo.

Half two: what happens after the drain

This is where the regulators got involved, and it’s the more serious half.

The cyclic silicones D4, D5 and D6 were identified in the EU as substances of very high concern. Very persistent, very bioaccumulative, and in D4’s case toxic as well. They resist breaking down in the environment and they accumulate in organisms over time.

D4 and D5 were already capped at 0.1% in wash-off cosmetics from January 2020, under an earlier version of the same rule. The 2024 decision rewrote it: D6 joined them, a general market ban on all three took effect on June 6, 2026, and leave-on cosmetics come under the cap from June 6, 2027.

Dimethicone, the silicone you’ll see most often on a haircare label, is not in this group. It’s a linear silicone rather than a cyclic one, and it isn’t covered by the restriction. The gap in how regulators treat the two is wider than most “silicone-free” marketing suggests: while Europe was restricting the cyclics, the US FDA has dimethicone on its approved list of over-the-counter skin protectants, usable at anywhere from 1% to 30%.

Worth knowing, because “silicone” gets used as one word for a family of ingredients that regulators clearly treat differently.

On the label	Which one	Restricted in the EU?
Cyclotetrasiloxane	D4	Yes. Rinse-off since January 2020, leave-on from June 2027
Cyclopentasiloxane	D5	Yes, on the same timetable as D4
Cyclohexasiloxane	D6	Yes, added by the 2024 decision
Dimethicone	Linear, not cyclic	No, and the FDA lists it as a skin protectant
Other names ending in -cone	Usually linear too	No

One thing the table can’t tell you: the restriction is about where these end up, not about what they do to your scalp. D4 is classed as persistent, bioaccumulative and toxic, and D5 and D6 as very persistent and very bioaccumulative. Those are environmental classifications. Nobody restricted them because they damaged anyone’s hair.

So should you avoid them

Depends what you’re optimizing for, and I’d rather give you the split than a blanket rule.

For hair health, silicones aren’t a safety problem. They’re a preference. Fine hair goes limp under them faster, curly hair often does better without them because the coating fights the moisture curls need, and thick or frizz-prone hair frequently loves them. If your hair looks good and feels light, nothing here says stop.

For the environment, the cyclic ones are a real issue and Europe has now acted on it. Every shower sends them down the drain, wastewater treatment doesn’t fully remove them, and they persist once they arrive. That’s the same shape of problem as optical brighteners in laundry: a cosmetic benefit paid for downstream.

If you want a simple rule: skip the cyclic ones, treat dimethicone as a personal preference.

Reading the label

Almost everything ending in “-cone,” “-conol,” “-silane” or “-siloxane” is a silicone. Dimethicone, amodimethicone, cyclopentasiloxane, cyclohexasiloxane, dimethiconol.

The cyclic ones to skip are the “cyclo-” names: cyclotetrasiloxane is D4, cyclopentasiloxane is D5, cyclohexasiloxane is D6. If a product is formulated for the EU market it should already comply, but a US-market product has no such requirement, so the name is what you have to go on.

What I’d actually buy

Every brand on our list of the best clean shampoo and conditioner leaves silicones out, so this is another case where a certification or a clean-formulation policy does the reading for you.

Innersense is the one to try if you’re worried that going silicone-free means accepting frizz, because it’s built to deliver slip from plant oils rather than a synthetic coating. Rahua does the same at the luxury end. Everist skips them in a waterless concentrate that also drops the plastic bottle.

If you’re coming off years of silicone products, expect a rough fortnight. Hair that’s been coated for a long time looks worse before it looks better, because you’re seeing its real condition for the first time. A single clarifying wash at the start speeds that up considerably.

Frequently asked questions

Are silicones bad for your hair?

Not harmful, but not right for everyone. They coat the hair shaft, which smooths frizz and adds shine, and the tradeoff is potential build-up that weighs hair down. Fine hair and curly hair tend to do worse under them. Thick or frizz-prone hair often does better with them.

Which silicones did the EU restrict?

D4, D5 and D6, the cyclic silicones, on environmental grounds rather than health ones. They’re classed as very persistent and very bioaccumulative. D4 and D5 have been capped at 0.1% in rinse-off cosmetics since January 2020. The 2024 decision added D6, set a general market ban from June 6, 2026, and extends the cap to leave-on products from June 6, 2027. Dimethicone, a linear silicone, isn’t covered at all.

How do I remove silicone build-up?

A clarifying shampoo, or any shampoo strong enough to lift a non-soluble coating. Water-soluble silicones (PEG- and PPG- prefixes, or names ending in “-conol”) rinse out with normal washing. The build-up problem usually appears when someone pairs a very gentle shampoo with a silicone-rich conditioner.

Is dimethicone safe?

It’s considered safe on skin and hair and isn’t part of the EU restriction, since it’s a linear silicone rather than a cyclic one. Whether you want it is a preference about how your hair behaves, not a safety question.

Silicones in Hair Products: What the EU Just Restricted, and Why

Half one: what silicones do to your hair

Half two: what happens after the drain

So should you avoid them

Reading the label

What I’d actually buy