Levulinic Acid

Levulinic acid is used mainly as a preservative/pH-adjusting organic acid (often paired with sodium levulinate) at low concentrations, where it is generally well tolerated but not truly inert. As an acid, it can contribute to stinging and barrier discomfort—especially on compromised or eczematous skin and in leave-on products with lower pH—so I rate it as mild irritancy potential with occasional sensitivity in reactive individuals. Safety Notes: In commercial skincare, levulinic acid is most often used as part of preservative systems (commonly with sodium levulinate/potassium sorbate) where it can appear at very low levels around 0.05–0.3% in leave-on and rinse-off products to aid antimicrobial performance and pH control. Higher consumer-available “acid” toners/serums and some deodorant/antimicrobial leave-ons use levulinic acid as a primary acidulant/functional antimicrobial, with observed use levels commonly ~1–2% and up to about 3% in specialized high-strength OTC products, above which irritation/pH constraints typically limit use.