Zits always show up at inopportune times—just before a first date or the morning of a big interview—so when they do pop up, you want to zap them ASAP. When it comes to OTC acne treatments, benzoyl peroxide (BPO) and salicylic acid are usually the staples. They both attack acne-causing grime and bacteria, but that's where the similarities between the super-ingredients end. They tackle different issues and work differently, but people often use them interchangeably. We spoke to two experts who explain the difference between these ingredients so you can figure what works for your condition and skin type the most.
What is benzoyl peroxide?
“BPO is a topical medicated agent that is able to kill the p.acnes bacteria that can cause acne," says Dr Chytra Anand, cosmetic dermatologist and founder, Kosmoderma Clinics and chief formulator, SkinQ. When it is applied, it degrades and releases oxygen, which kills the bacteria. Benzoyl peroxide kills the bacteria (unlike antibiotics, which only slows down their growth), so it has not shown to contribute to any bacterial resistance. “It reduces inflammation and works well on mild to moderate acne, including whiteheads,” she says. It is best to treat inflammatory acne—the kind that is red, hot and painful to touch—says Dr Stuti Khare Shukla, cosmetic dermatologist and founder, Elements of Aesthetics Clinics.
It can cause dryness and irritation if you layer on too much of it, so doctors suggest applying a very small amount only on the actual zit or inflamed area. Plus, it fits well into a prescription-based acne routine too. “Benzoyl peroxide works best in combination with retinols and antibiotics like clindamycin,” says Dr Anand. But it can cause peeling and flaking, so it is best to moisturise well after. Another word of caution? Keep the sun protection close by. “BPO can give you post-inflammatory pigmentation (especially if you have dry or sensitive skin), hence it is advised to use in your PM routine only, and really slather on sunscreen in the morning," says Dr Shukla. It has to be applied only on super dry skin, because the absorption of BPO is increased if the skin is wet and can lead to erythema and irritation.
What is salicylic acid?
Unlike BPO, salicylic acid does not kill the bacteria, so it can be used in conjunction with different products for a complete treatment of your acne. It is a beta hydroxy acid that is keratolytic and comedolytic, which means that it dissolves dead skin cells on the surface of the skin, and then gets down to the pores, dissolves the oil and breaks apart the debris inside that can lead to acne. When you apply it on areas you're prone to whiteheads and blackheads (like your T-zone, cheeks or nose) it can stop acne from occurring in the first place. It is very oil soluble, so it can cut through the grease on very oily skin to reach the inside of each pore and really get to work.