Written for Stock My Medicine and clinically reviewed by Hajra Dhanchora, MPharm (GPhC 2216990).
Benzoyl peroxide is the acne treatment dermatologists reach for first, and the one most people give up on in week two because their face went red and flaky. Both facts are true, and the second is avoidable. Here's what it does, how to use it so your skin tolerates it, and how long to give it before judging.
What does benzoyl peroxide do?
Two things spots need: bacteria and blocked pores. Benzoyl peroxide releases oxygen into the pore, which kills the acne bacteria (C. acnes) that can't survive in oxygen, and it loosens the plug of dead skin and oil that blocks the pore in the first place. Because it kills bacteria chemically rather than the way an antibiotic does, bacteria can't become resistant to it, which is why it's used alongside or instead of antibiotic treatments and why it keeps working year after year.
Is benzoyl peroxide good for acne? Which acne?
It's best for mild to moderate acne: blackheads, whiteheads and the red, inflamed spots that come and go across the face, chest or back. It's less effective on its own for deep, painful nodules and cysts, which need a GP, and it does nothing for the marks spots leave behind except prevent new ones. If your acne is scarring, or you've had three months of proper use without improvement, that's the point to see a GP rather than buy a stronger tube.
Which strength: 2.5%, 5% or 10%?
Trials show 2.5% and 5% clear spots almost as well as 10%, with far less irritation, so start low. Acnecide Face 2.5% suits sensitive or first-time skin; Acnecide 5% is the standard; the 10% strength is a pharmacy medicine kept for acne that's tolerated the 5% but not cleared. For the back and chest, a wash-off benzoyl peroxide is gentler and covers large areas. Our Acnecide range has all of them.
How to use benzoyl peroxide gel
Cleanse with something mild, pat dry and wait a few minutes. Apply a thin layer over the whole spot-prone area, not just the individual spots, because it works by preventing the next ones. For the first week, use it once a day, or every other day if your skin is sensitive, and build to twice a day only if the skin stays comfortable. Follow with a plain, oil-free moisturiser; it doesn't cancel the treatment and it halves the peeling. Use SPF 30 or more in the day, because treated skin burns more easily.
Does benzoyl peroxide cause purging?
Not in the way retinoids do. What people call purging with benzoyl peroxide is usually irritation: dryness, redness, tightness and peeling in the first two to three weeks as the skin adjusts. It's expected and it settles, but it's a signal to slow down, not push through. Drop to alternate days, moisturise more, and stop if the skin swells, blisters or stings badly. Spots do not need to get worse before they get better.
Does benzoyl peroxide bleach skin?
No. It bleaches fabric and hair, not skin, and that's the side effect that catches everyone: orange-stained pillowcases, spotted towels and lightened hairlines and eyebrows. Use white bedding and towels, wash your hands after applying, and let it dry fully before getting dressed. Any temporary lightening of the skin is from the peeling and evens out; it doesn't change your skin colour.
How long does benzoyl peroxide take to work?
Bacteria numbers drop within days, but the spots you can see were weeks in the making. Expect the first visible improvement at four to six weeks, and the full effect by eight to twelve. Judge it at twelve weeks of consistent use, then keep going, because acne is a tendency, not an infection; stop and it drifts back. Once clear, many people hold it at once a day or a few times a week.
Can I use it with retinol or other acne products?
Retinol and benzoyl peroxide together irritate, and benzoyl peroxide breaks down some retinoids, so use them at different times: benzoyl peroxide in the morning, retinol at night. Adapalene is the exception and is often paired with it. Don't add salicylic acid, scrubs or alcohol toners in the early weeks, and don't combine two benzoyl peroxide products without a pharmacist's advice. It's safe alongside most other medicines; ask our pharmacist if you're pregnant or on a prescription acne treatment. For everything else in the range, see our skin treatments.
Frequently asked questions
Can teenagers use benzoyl peroxide?
Yes, from around 12; it's the standard first treatment for teenage acne. Start on the 2.5% or 5% and once a day.
Should I put it on spots or the whole face?
The whole area that gets spots. Dabbing it on individual spots treats the ones you have and ignores the ones forming underneath.
When should I see a GP about acne?
Deep, painful lumps; scarring; acne that's affecting your mood; or no improvement after three months of proper use. Prescription treatments work well and the sooner scarring is prevented, the better.