Category: topical
Aliases: α-hydroxyphenylacetic acid, almond AHA
Aromatic α-hydroxy acid with a benzene ring — the largest commonly-used AHA. Slow and even stratum-corneum penetration compared with glycolic acid, producing substantially less irritation and a smaller pH drop for equivalent concentration. Modest keratolytic activity plus antibacterial effect against P. acnes and S. aureus — hence preferential use in darker phototypes, rosacea-prone skin, and melasma where aggressive peels are poorly tolerated.