Propylene Glycol (Cosmetic) vs Urea (Cosmetic): which is worse?

What is Propylene Glycol (Cosmetic)?

Propylene glycol is a small synthetic organic compound (diol) used in cosmetics as a humectant, solvent, and skin-conditioning agent. It is produced from propylene oxide (petroleum) but also from bio-based sources.

What is Urea (Cosmetic)?

Urea is a naturally occurring organic compound that is a byproduct of protein metabolism, found in urine and skin. In cosmetics, synthetic urea is used at varying concentrations for different effects: 2–10% as a humectant; 10–20% as a keratolytic (softening/exfoliating thickened skin); 20–40% for calluses and nail penetration.

Documented risks

Propylene Glycol (Cosmetic): Propylene glycol is safe at typical cosmetic use concentrations (1–15%). The CIR and EU SCCS have both reviewed and affirmed its safety. It can cause contact sensitization and irritant reactions in some individuals, particularly at concentrations above 5% in leave-on products; those with sensitive or compromised skin may react. It is rapidly metabolized if absorbed and is not bioaccumulative. There is no evidence of carcinogenicity or endocrine disruption at cosmetic use levels. Note: this entry covers topical cosmetic use; ingested large doses (antifreeze context) are toxic, which is a separate matter.

Urea (Cosmetic): Cosmetic urea is safe and has been used for decades in dermatology for very dry and keratotic skin conditions. The CIR has confirmed safety at cosmetic concentrations. At concentrations above 10%, it may cause mild stinging on broken or inflamed skin. No carcinogenicity or hormone disruption is documented. Urea is considered an active ingredient in OTC skin softeners in Europe.