Citric Acid

Evidence by route

About this ingredient

Citric Acid is a weak tricarboxylic α-hydroxy acid (AHA), naturally found in citrus fruits, berries, tomatoes. In cosmetics used as a pH regulator, mild chelator (binds metal ions that accelerate oxidation), less often as an AHA exfoliant. Made synthetically or by fermentation of Aspergillus niger on sugar. Where applied. Practically all water-based cosmetics – adjusts formula pH to the target 4-6 (acidic, matching skin mantle). Also a chelator in shampoos, shower gels. Use concentration 0.1-2%. As exfoliant – 5-10%. In Spain – in CeraVe, La Roche-Posay, Bioderma, Mádara, thousands of brands. Mechanism. As a pH regulator – neutralizes alkaline formula components. As a chelator – binds Ca, Mg, Fe, slowing oxidation and microbial growth. As an AHA – weakens corneocyte bonds in the stratum corneum, accelerates exfoliation. Stimulates dermal collagen synthesis with long-term use (Bernstein 2001). Evidence base. As AHA – at 5-10% and pH 3-4 moderate exfoliative effect, comparable to weak glycolic acid. RCTs (Stiller 1996, Smith 1996) showed improvement in texture, tone, mild fine-wrinkle reduction over 6-12 weeks. In superficial hyperpigmentation – intensity reduction over 12-24 weeks. Safety. CIR confirmed safety across all use concentrations. SCCS imposed no restrictions. Hypoallergenic, non-comedogenic. Above 10% or at pH <3 irritation, burning, erythema possible. Photosensitizes with long-term use – SPF mandatory. Pregnancy and lactation – safe. As a cosmetic pH regulator – safe at any stage. As an AHA exfoliant – same restrictions as other AHAs: under 5% safe, above – individual decision. Suitable for. Universal as a pH regulator and chelator. As AHA – patients with photoaging, post-inflammatory hyperpigmentation, texture issues. Not suitable for severe rosacea and couperose – even weak AHA increases redness.

Tolerability and safety

Skin types

Frequently asked questions