What is Stearic Acid?
Stearic Acid falls into the fatty acid category — a fatty acid. A C18 fatty acid used as a thickener and emulsion stabiliser. Rated 2/5; commonly avoided in strict fungal-acne routines.
You may see it on labels as Stearic Acid, Octadecanoic Acid, so it can hide under more than one name in an ingredient list.
Where Stearic Acid shows up
As a fatty acid, Stearic Acid typically appears in cleansers, cream bases, and bar soaps, where it builds texture and lather. Separately from clogging, its irritancy is rated 0/5 — low, so it's unlikely to sting or sensitise on its own.
Is Stearic Acid bad for acne-prone skin?
Because it barely registers on the comedogenic scale, Stearic Acid is generally a safe pick for breakout-prone skin and is often recommended as a gentler alternative to heavier ingredients.
Note for fungal-acne (malassezia) sufferers: Stearic Acid is commonly avoided in fungal-acne routines, since it falls into the fatty-acid or ester families the yeast can feed on. The evidence there is looser than for comedogenicity — see our fungal-acne checker for context.