Sodium Citrate

Sodium citrate is primarily a pH buffer/chelating salt used at low concentrations (typically ~0.1–1%) to stabilize formulations and is generally well-tolerated in patch testing and clinical use. However, as a pH-adjusting agent it can cause mild stinging on compromised or very inflamed skin (e.g., eczema flares), especially if the overall formula’s pH shifts toward more acidic/alkaline ranges. Given the low but non-zero irritation potential in highly reactive populations, it fits best as very gentle rather than completely inert. Safety Notes: In commercial skincare, sodium citrate is most commonly used as a pH adjuster/buffer and chelating adjunct, where it is frequently present at trace-to-low levels (~0.01–0.3%) in both leave-on (serums, creams) and rinse-off (cleansers) products. Higher levels are seen when it functions as a primary buffering component in citrate buffer systems for acidic formulas (e.g., AHAs, vitamin C derivatives) and in some cleansing/bar-type systems, with consumer-available products reaching ~1–5% depending on pH target and ionic strength. Sodium citrate is not specifically restricted by EU/FDA for general cosmetic use, so the upper end is driven mainly by sensorial/tolerance and formulation stability rather than regulation.