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Isostearic Acid

What Isostearic Acid is & what it does

A branched fatty acid used as an emollient and pigment dispersant that conditions skin and gives a smooth feel. It helps distribute pigments and filters.

What is Isostearic Acid and what does it do in sunscreen?

Isostearic Acid is a branched fatty acid used as an emollient and a pigment dispersant. It conditions skin and gives a smooth feel, and its branched structure helps spread and evenly distribute mineral pigments and filters so they do not clump. That even dispersion is part of why it shows up in tinted and mineral sunscreens.

Is Isostearic Acid safe?

Yes. It is a long-used cosmetic fatty acid that is well tolerated at the levels found in skincare and sunscreen. Unlike straight-chain fatty acids, its branched form stays liquid and gives a lighter feel. It works on the skin surface and is not associated with notable concern for most people.

Does Isostearic Acid clog pores?

Generally no. It is not flagged as comedogenic in our data, and its branched, liquid structure makes it lighter than many straight-chain fatty acids. It is used in modest amounts mainly to disperse pigments. If you are breaking out, heavier oils and waxes elsewhere in a formula are the more likely cause.

Is Isostearic Acid fungal-acne safe?

Yes, by our data. It is not flagged as a fungal feeder, meaning malassezia yeast is not known to readily use it the way it uses many free fatty acids and certain esters. People prone to fungal acne can generally consider it lower risk, though the overall formula matters most. If in doubt, patch test.

Is Isostearic Acid natural or synthetic?

It is usually made synthetically by branching stearic acid, even though stearic acid itself can come from plant or animal fats. The branching step is what gives it its liquid, light feel. So the finished ingredient is engineered rather than found in nature in this form.

Sunscreens with Isostearic Acid

We rate 417 sunscreens that contain it, showing the top 10 by overall score:

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