active
Citric Acid
Ubiquitous pH adjuster, chelating agent, and mild AHA in cosmetic formulations. Provides buffering, stabilisation, and pH management across product types.
Benefits
- pH adjustment and buffering
- Chelating agent — reduces heavy metal-catalysed oxidation
- Mild AHA exfoliation at higher concentrations
- Preservative system enhancement
- Antioxidant via metal chelation
Example uses
- Foaming gel cleansers
- Vitamin C serums (pH management)
- Purple shampoos
- Brightening toners
- SPF sunscreens (stabilisation)
Mechanism of action
Tricarboxylic acid buffers via proton donation/acceptance across three pKa values (3.13, 4.76, 6.40). Chelating activity via tridentate coordination of divalent metal ions preventing Fenton reactions. At pH <4 and higher concentrations functions as AHA via corneodesmosomes disruption.
Clinical evidence · High
Well-characterised. Efficacy as pH adjuster and chelator definitively established. AHA mechanism established.
Effective concentration range
0.1–5% (pH adjustment); up to 10% (exfoliant)
Formulation notes
Highly water-soluble across all cosmetic pH. At high concentrations (>5%) functions as chemical exfoliant; at low concentrations purely as pH adjuster.
Watchouts
At exfoliant concentrations increases photosensitivity. Stronger than some AHAs at equivalent pH.
Stacks with
Market positioning
Sold as natural pH adjuster and preservative system enhancer. Accurate. Exfoliant function at higher concentrations sometimes underreported.
Comedogenicity
0 / 5
Sensitisation risk
Low
INCI & aliases
Citric Acid
2-hydroxypropane-1,2,3-tricarboxylic acid
Clean beauty perception
Universally accepted in clean beauty. Naturally occurring in citrus fruits. EWG rating 1.
Graph relationships
Timeline