Hydrogen Peroxide

Hydrogen peroxide is a strong oxidizing agent; at common consumer/OTC concentrations (around 3% for antiseptic use, higher in professional settings) it frequently causes stinging, erythema, and chemical irritation, especially on compromised or eczematous skin. Patch/clinical experience consistently shows it can damage the stratum corneum and delay barrier recovery, with risk increasing markedly with occlusion, repeated exposure, or higher concentrations. Given the high likelihood of irritation in sensitive populations and the potential for caustic injury when misused, it warrants a very high irritancy score. Safety Notes: In consumer skincare/personal-care products, hydrogen peroxide is most commonly encountered at the low end around 0.5–1% in mild antiseptic/cleansing or acne-spot style products (where it is typically short-contact or used sparingly due to irritation/oxidation potential). The highest widely observed OTC consumer concentration for skin-related use is 3% (the standard “drugstore” hydrogen peroxide solution sometimes marketed for first aid/skin cleansing), with higher concentrations (e.g., 6–12%+) generally restricted to hair bleaching or professional/prescription contexts rather than typical leave-on facial skincare.