Linolenic Acid

Linolenic acid (an omega-3 fatty acid, typically used at low percentages as an emollient/skin-conditioning lipid) is generally well-tolerated and can support barrier function, which lowers baseline irritancy risk compared with exfoliating actives. However, as an unsaturated fatty acid it can oxidize in formulations, and oxidized lipids may increase stinging/irritant reactions in highly reactive or eczematous skin, so it is not best classified as “very gentle.” In real-world routines—especially on compromised skin or with concurrent actives—this warrants a conservative “gentle” score rather than an exceptionally low one. Safety Notes: In commercial products, linolenic acid (typically alpha-linolenic acid) is often present at very low levels (around 0.001–0.05%) as a minor component of botanical oils/extracts or as a declared standalone fatty-acid add-in for barrier-support leave-on creams/serums. Dedicated lipid-replenishing leave-on treatments and “pure fatty acid” booster-style products can reach ~1–5% linolenic acid, but higher levels are uncommon in OTC skincare due to oxidative instability (rancidity/odor/color shift) and irritation risk, so brands more often use stabilized blends or encapsulation rather than pushing beyond this range.