Benzoyl Peroxide

Benzoyl peroxide is 过氧化苯 (guò yǎng huà běn) in Chinese, often written in full as 过氧化苯甲酰 or abbreviated BPO; Taiwan uses 過氧化苯甲醯. It's an antibacterial acne active that kills C. acnes by releasing reactive oxygen.

It won't thin skin, but it does worsen dryness and peeling. It works by killing bacteria, not exfoliating, so at a sane strength and frequency (2–5%, every other day or 3x weekly) plus a moisturizer, the barrier stays healthy. Obvious dryness, itching, or redness means the dose or frequency is too high.

Common reasons: concentration too low (under 2%), less than 4 weeks of use (it needs at least 2 to show), applying too infrequently, stacking other irritants, or acne that isn't bacterial (hormonal, for example). Commit to 2–3 weeks of consistent use and drop the other irritants first.

Yes, but stagger them: benzoyl peroxide (2–5%) in the morning, tretinoin at night, at least 8 hours apart. The combo clears acne better, but early on it's drying and irritating — start with low concentrations and ramp up frequency gradually.

Judge at 4–8 weeks. If acne clearly improves, step down to every other day or 2–3x weekly for maintenance. No improvement by 6–8 weeks, or steadily drier and more sensitive skin, means it isn't working for you — switch to another option (fusidic acid, isotretinoin, etc.).

Yes. That's a peroxide trait — contact with dark fabric or hair can strip color. Let the product dry fully before it touches clothing, rinse thoroughly after washing your face, and watch for residue on towels and pillowcases.