Citric Acid
Also known as 2-Hydroxy-1,2,3-propanetricarboxylic acid, 3-Carboxy-3-hydroxypentanedioic acid, E330
“CIR Expert Panel says: safe as used in cosmetics.”
Citric Acid (2-hydroxy-1,2,3-propanetricarboxylic acid; CAS 77-92-9; C6H8O7) is a weak tricarboxylic acid and intermediate of the Krebs cycle. In cosmetic formulations it functions primarily as a pH adjuster/buffer and as a mild chelating agent (sequestering divalent metal ions such as Ca2+, Mg2+, and Fe2+). It is chemically and biologically distinct from the alpha-hydroxy acids (glycolic and lactic acid) despite being carboxylic — the CIR assessment explicitly notes this distinction because the AHA safety literature does not automatically apply to citric acid. The CIR Expert Panel assessed citric acid together with 12 inorganic citrate salts and 20 alkyl citrate esters (Fiume, Heldreth, Bergfeld et al., Int J Toxicol 33(2 Suppl):16S-46S, 2014, PMID 24861367; CIR Final Report March 2012) and concluded these ingredients are safe in the present practices of use and concentration. Citric acid, calcium citrate, ferric citrate, manganese citrate, potassium citrate, sodium citrate, diammonium citrate, isopropyl citrate, stearyl citrate, and triethyl citrate are FDA Generally Recognized As Safe (GRAS) direct food additives, so the CIR assessment focused primarily on dermal exposure for cosmetic use cases. Citric acid is ubiquitous in cosmetic formulations as a pH adjuster (typically 0.01-0.5%), where its weak acidity and buffering capacity make it the default choice for neutralizing alkaline surfactant bases. The QRT row carries no conditions or concentration limits for citric acid itself.
Primary pH adjuster/buffer in cosmetic formulations — weak acidity and dual buffering capacity make it the default neutralizer for alkaline surfactant and emulsion bases
Mild chelating agent that sequesters divalent metal ions (Ca2+, Mg2+, Fe2+), improving formulation stability and preventing metal-catalyzed oxidation of sensitive actives
CIR Expert Panel concluded safe as used in cosmetics (Fiume et al., IJT 2014, PMID 24861367) — same assessment also clears 12 inorganic citrate salts and 20 alkyl citrate esters
FDA Generally Recognized As Safe (GRAS) as a direct food additive; long history of safe food and cosmetic use; also approved as food additive E330 in the European Union
Krebs-cycle intermediate with no systemic toxicity at cosmetic-relevant exposure levels
- · Citric acid is a weak acid; at high topical concentrations (>10%) it can cause skin irritation, though typical cosmetic use (0.01-0.5% as pH adjuster) is well below any irritation threshold
Not to be conflated with alpha-hydroxy acid exfoliation — the CIR assessment explicitly distinguishes citric acid (tricarboxylic, used as pH adjuster) from glycolic/lactic acid AHAs (used as exfoliants); citric acid does not share the AHA safety considerations for sun sensitivity
CIR Quick Reference Table (12/2017, revised 07/2018) - Citric Acid row: Finding 'S' (Safe), Citation 'IJT 33(S2):16-46, 2014'
“Citric Acid | S | [no detail column entry] | IJT 33 (S2): 16-46, 2014”— QRT-122017revised072018.pdf, p. 26