What it is
Arachidic acid is a saturated, twenty-carbon (C20) fatty acid found naturally in some plant oils, including peanut and other seed oils. In cosmetics it is used to help stabilize emulsions, build viscosity, and contribute a smooth, emollient feel, and it can lend opacity to creams. Being a solid wax-like fatty acid, it supports the structure and texture of the emulsion phase.
Safety & warnings
Saturated fatty acids of this type are generally well tolerated and low in irritation potential. As a long-chain fatty material, it may have some comedogenic potential in very rich formulas for acne-prone users, though it is typically used at low structural levels.
Origin & sourcing
Can be plant-derived (occurring in peanut and other vegetable oils) or produced synthetically; it is a saturated long-chain fatty acid.
Questions everyone asks
What does arachidic acid do in a sunscreen?
It helps stabilize and thicken the emulsion and contributes a smooth, emollient feel, and can add opacity.
Is arachidic acid related to peanuts?
It occurs naturally in peanut and other vegetable oils, which is the origin of its name, but the cosmetic ingredient is a purified fatty acid.