Common Name(s): Lemon acid,2-hydroxypropane-1,2,3-tricarboxylic acid

CAS Number: 77-92-9

DESCRIPTION

What It Does: Adjusts ph to optimal ranges, chelates destabilizing metal ions, provides mild exfoliation at higher concentrations.

Why It's Used: Universal cosmetic ph adjuster and chelating agent. aha exfoliant activity is secondary.

How It Works: As ph adjuster, donates protons. as chelating agent, three carboxylic groups bind divalent metals (ca²⁺, mg²⁺, fe²⁺) preventing oxidative degradation.

Typically Found In: Nearly all cosmetic formulations,brightening products,exfoliants

TECHNICAL DETAILS

Primary Category: Active ingredient – alpha hydroxy acid (aha)

Secondary Functions: Chelating agent,ph adjustment,preservation enhancement

Application Areas:

Typical Concentration Range: 0.1%–10%

SOURCING & ETHICS

Vegan Status: Yes – synthetic or fermentation-derived

Halal Status: Yes

Source Notes: Produced by fermentation of sugars by aspergillus niger. gras (e330). most abundant organic acid in citrus.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low at low concentrations; 2/5 at exfoliant concentrations

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Photosensitizing – mandatory spf use. start at low frequency.

Safe for Sensitive Skin: Use with caution – spf required

SAFETY & COMPATIBILITY

Safety Profile: Safe at otc concentrations. eu: ≤10% leave-on at ph ≥3.5. mandatory spf advisory.

Works Well With: Niacinamide,ceramides,hyaluronic acid,spf

Avoid Combining With: Retinol in same step; multiple exfoliants simultaneously

SCIENTIFIC NOTE

Three carboxylic acid groups provide multiple proton donation sites and stronger chelation than monocarboxylic ahas. this makes citric acid the preferred cosmetic chelating agent alongside edta.

Last Verified: 2026-03-12

Primary Sources: Cosing database,cir safety assessment,ewg skin deep