Malic Acid

Malic acid is an alpha-hydroxy acid used for exfoliation and pH adjustment; when present at exfoliating-use levels (commonly ~1–10% in leave-on products) it can cause stinging, erythema, and barrier disruption, especially in eczema-prone or compromised skin. Clinical and real-world experience with AHAs shows irritation risk is strongly dose- and pH-dependent, and malic acid is not an exception—cumulative use with other actives (retinoids, benzoyl peroxide, other acids) increases the likelihood of significant irritation. Given sensitive-skin populations and the potential for painful reactions when mis-layered or used on impaired barriers, it warrants a significant-potency score. Safety Notes: In commercial skincare, malic acid is frequently used at very low levels (~0.01–0.5%) as a pH adjuster/chelator or minor AHA component in cleansers, toners, and creams, sometimes as part of a broader fruit-acid blend. At the high end, it appears in consumer-available AHA peel/exfoliant products (typically rinse-off masks/peels) where malic acid can be a major acid in the blend, reaching ~20–30% in specialty at-home peel formulations; leave-on products are generally far lower due to irritation and pH constraints. There is no specific FDA/EU maximum percentage limit for malic acid in cosmetics, but practical upper use levels are governed by product pH, buffering, and consumer tolerability.

Suitability