Ci
Citric Acid
Citric AcidExfoliant
Citrus-derived AHA. Most common use is pH adjustment; weaker exfoliant than glycolic or lactic acid.
What it does
Citric acid is technically an alpha hydroxy acid, but its most common cosmetic role is pH adjustment — bringing a formulation into its target acidic pH window. As a stand-alone exfoliant it's weaker than glycolic or lactic acid at comparable concentrations. Citric acid is also a chelator, binding trace metals that would otherwise destabilize formulations.
The evidence, graded
expert consensusAHAs and BHAs can be combined safely in well-formulated products. The 'never mix them' rule is overstated — the real concern is total acid load on the skin barrier, not the chemistry of mixing them.Kornhauser 2010 · Clinical and Cosmetic Investigative Dermatology ↗
emergingAHAs (glycolic, lactic, mandelic) need an acidic pH (typically 3.5–4) to deliver advertised exfoliation. Products with neutral or partially neutralized pH still hydrate but won't drive meaningful keratolysis.Smith 1996 · Journal of the American Academy of Dermatology ↗
Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.
Pairs worth knowing
Browse all 668 ingredients — grouped by what they do, each with whatever evidence we can cite.
This page is public so a shared ingredient card always has its sources behind it — and so you can check them without an account.
Want more like this?
Every evidence-based flag cites its source, Drop tells you when your routine is complete, and it helps you simplify — instead of selling you more. The app launches on iOS and Android in October 2026. Rate my routine works today at /rate — no sign-in.