Mandelic Acid
Genuinely relevant for some people, or depends on dose and pH.
Also written as: AHA · Alpha Hydroxy Acid · Phenylglycolic Acid
What it is
Mandelic acid is an aromatic alpha hydroxy acid originally derived from bitter almonds and now made synthetically. Its molecule is roughly four times heavier than glycolic acid's, so it moves into the skin more slowly and evenly, which is why dermatologists often suggest it for darker or reactive skin. It also has mild antibacterial activity, which is one reason it appears in acne-focused masks and toners.
What it does well
Slower, more even penetration than smaller AHAs
Its size limits how fast it enters the skin, which in practice means less immediate stinging at comparable strengths. Clinical trials of mandelic acid peels report good tolerability, including in medium and darker skin tones.
Moderate evidence
Worth knowing
The AHA sun-protection advice still applies
Mandelic acid was not studied separately in the EU advisory committee's UV work, but as an alpha hydroxy acid it is treated the same way: use sunscreen while exfoliating regularly.
Matters most toAnyone using it as a regular leave-on treatment, particularly in summer.
Where the EU stands
No specific restriction
Not listed in any Annex of the EU Cosmetics Regulation, so there is no legal maximum concentration. The general safety obligation on the responsible person applies.
Sources (1)
Every link goes to the original: a journal, a PubMed record or an EU document.
- [1]Effects of Topical Mandelic Acid Treatment on Facial Skin Viscoelasticity
Facial Plastic Surgery · 2018 · doi:10.1055/s-0038-1676048
Objective cutometer measurement showed topical mandelic acid improved facial skin viscoelasticity, though the study was small and conducted by the developers of the formulation.