Myristic Acid

Myristic acid is a saturated fatty acid primarily used as a surfactant/cleansing and opacifying agent (often via soaps/salts) and can be present at meaningful levels in cleansers and bar soaps. While not a classic high-risk allergen, fatty-acid–based surfactants and soaps can disrupt the stratum corneum and increase transepidermal water loss, leading to stinging, dryness, and eczema flares—especially with frequent use or high-pH formulations. In sensitive or eczematous skin, the barrier-disruptive potential justifies a mild irritancy rating for patient safety. Safety Notes: In commercial skincare, myristic acid is often a minor co-emollient/co-surfactant or soap-structuring fatty acid in leave-on creams/lotions and some cleansers, where it can appear at trace-to-low levels (~0.05–1%). The highest consumer-available levels are found in high-foaming rinse-off facial cleansers and “soap-based” cleansing creams/bars (often paired with lauric/palmitic/stearic acids and neutralized with KOH/NaOH), where myristic acid can be a major fatty-acid feedstock reaching ~10–25% of the formula. Leave-on products rarely approach the upper end due to waxy feel and higher comedogenic/irritation potential; the upper range is mainly rinse-off.