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Steareth-21

What Steareth-21 is & what it does

An emulsifier usually paired with steareth-2 to create stable, smooth emulsions. It keeps oil and water evenly blended.

What is Steareth-21 and what does it do in sunscreen?

Steareth-21 is an emulsifier made by attaching about 21 units of ethylene oxide to a fatty alcohol, which makes it more water-loving. In sunscreen it is usually paired with the more oil-loving Steareth-2 to keep oil and water evenly blended in a stable cream. Together they give the formula a smooth, consistent texture.

Is Steareth-21 safe?

Yes. The steareth emulsifiers are long-established and widely used in cosmetics, and they are considered safe at the levels used in skincare and sun care. Steareth-21 is not flagged as an allergen in our data and is well tolerated by most people. As with other ethoxylated ingredients, reputable manufacturers purify out trace processing by-products, so the concern is a contaminant rather than the ingredient.

Does Steareth-21 clog pores?

Generally no. Steareth-21 does not carry a comedogenicity flag in our data, so it is unlikely to be a pore-clogging culprit. It is a water-loving emulsifier used in modest amounts rather than a heavy oil or wax. If your skin is breaking out, the richer emollients and oils in a formula are far more likely the cause.

Is Steareth-21 fungal-acne safe?

Not entirely. Steareth-21 is built on a fatty (stearyl) backbone, and the malassezia yeast behind fungal acne can feed on that kind of fatty ester. People prone to fungal acne (malassezia folliculitis) may prefer to avoid it as a precaution. This is one specific skin concern, not a general safety problem: for everyone else Steareth-21 is harmless and routine.

What is Steareth-21 on an ingredient list (INCI)?

Steareth-21 is the INCI name on the label, where the 21 refers to roughly 21 units of ethylene oxide on the fatty alcohol, not a percentage. The high number makes it more water-loving, which is why it is commonly partnered with the lower-numbered Steareth-2. You will usually find it in the middle of an ingredient list among the other emulsifiers.

Sunscreens with Steareth-21

We rate 135 sunscreens that contain it, showing the top 10 by overall score:

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