Benzoyl peroxide: an old acne treatment that still works

Benzoyl peroxide has been treating acne for decades, long before most of today’s trendy ingredients existed. It’s cheap, it’s everywhere, and it still sits near the top of acne guidelines. It also has a reputation: it dries your skin, ruins your towels, and in 2024 it made headlines over benzene. Here’s what it does, and how worried you should be.

How benzoyl peroxide works

Acne has a few ingredients: pores that clog with dead cells and oil, bacteria called Cutibacterium acnes that thrive in those clogged pores, and inflammation that turns a plug into a red pimple.

Benzoyl peroxide goes mainly after the bacteria. A 2025 review in Canadian Family Physician, which adapted the 2024 American Academy of Dermatology guidelines to Canadian practice, describes it as a topical antimicrobial that also reduces the irritating fatty acids bacteria produce in the pore, and has a mild unclogging effect. Being a peroxide, it works by oxidation, which is also why it bleaches fabric.

The same review points to its biggest advantage: no acne bacteria resistant to benzoyl peroxide have been reported. Antibiotic creams and pills can lose their punch as bacteria adapt. That’s why guidelines discourage using antibiotics on their own and recommend combining them with benzoyl peroxide to help limit resistance.

What the evidence shows

Benzoyl peroxide is one of the most-studied acne treatments. A 2020 Cochrane review pooled 120 trials with nearly 30,000 people. Its findings:

• People using benzoyl peroxide were more likely to report their acne improving than those on placebo or no treatment.
• There may be little to no difference between benzoyl peroxide and adapalene (a retinoid) or clindamycin (a topical antibiotic) in how much people improved.
• People were about twice as likely to stop treatment because of side effects on benzoyl peroxide than on placebo, mostly because of redness, itching and burning.

The Cochrane authors rated most of this evidence low certainty. Many trials had design weaknesses, and industry funded 50 of them, while 63 didn’t report their funding. Still, the overall picture is consistent, and the 2024 AAD guidelines, as summarized in the Canadian review, give benzoyl peroxide a strong recommendation for acne.

What Health Canada allows

In Canada, benzoyl peroxide acne products are non-prescription drugs, so the label carries a DIN (Drug Identification Number). Health Canada’s Acne Therapy Monograph, updated in December 2025, permits 2.5 to 5 percent, for adolescents 12 and older and adults. Anything stronger, any product combining it with another medicinal ingredient, and any product for rosacea is on the Prescription Drug List. The Canadian review notes a 10 percent cleansing gel is available by prescription.

The monograph requires labels to include these cautions, among others:

• Avoid contact with the eyes, lips, mouth and nostrils.
• Avoid contact with hair and dyed fabrics, which may be bleached.
• Avoid unnecessary sun exposure and use a sunscreen.
• Don’t use it on sensitive skin or if you’re allergic to benzoyl peroxide.
• Get medical help right away if you develop hives, swelling of the eyes or mouth, blistering or trouble breathing.
• Stop and see a health care provider if there’s no improvement within 6 to 8 weeks.

Dryness, irritation and bleached towels

Irritation is the main reason people give up. The Canadian review lists burning, dryness, fabric staining and bleaching as its side effects, and notes that lower concentrations and wash-off formulas are usually well tolerated.

Some practical ways to make it easier, drawn from the monograph’s directions and the review:

• Start with a lower strength, or a wash, and use it once a day at first. The monograph’s directions are to start with one application a day and cut back to every other day if dryness or peeling occurs.
• Apply a thin layer over the whole area, not just on individual spots.
• Use a gentle, fragrance-free moisturizer.
• Use one acne product at a time at first. The monograph warns that irritation is more likely when you use another topical acne product at the same time. If a doctor prescribes a retinoid too, note that most retinoids other than adapalene shouldn’t be combined with benzoyl peroxide, which can break them down.
• Switch to white towels and pillowcases, wash your hands after applying, and let it dry fully before your face touches fabric.

The benzene story, calmly

In March 2024, an independent US testing lab reported that benzoyl peroxide products could form benzene, a chemical known to cause cancer, especially when stored at high temperatures. That’s genuinely worth taking seriously, and it has been.

Here’s what happened next:

• Benzene isn’t added to these products. The American Academy of Dermatology explains that benzoyl peroxide can break down into benzene, especially when exposed to heat or kept for a long time.
• In March 2025, the US FDA tested 95 products. More than 90 percent had undetectable or extremely low benzene levels. Six had elevated levels, and several products were recalled in the US. The FDA concluded that even with daily use for decades, the cancer risk from this benzene is very low.
• In Canada, the Acne and Rosacea Society of Canada reports that Health Canada recalled a small number of over-the-counter benzoyl peroxide products in November 2025 because their benzene levels were above the allowable limit.
• Studies in people using benzoyl peroxide haven’t shown higher blood benzene levels or more cancer, according to both the AAD and the Acne and Rosacea Society, which notes more than 60 years of use without a cancer signal.

So neither organization is telling people to stop. Their practical advice:

• Store it at room temperature or cooler; the fridge is fine.
• Don’t leave it in a hot car or a steamy shower.
• Throw out products that are expired or have been exposed to heat.
• Replace benzoyl peroxide products every 10 to 12 weeks.
• Be cautious about ordering online, since shipping can expose products to heat.

If you’d rather avoid it altogether, that’s a reasonable personal choice. The AAD lists adapalene, salicylic acid and azelaic acid as alternatives, though in Canada adapalene needs a prescription.

You can compare the panel’s reviewed cleansers or filter for products suited to acne-prone skin.

Benzoyl peroxide earns its place: it’s well studied, bacteria don’t become resistant to it, and it’s available without a prescription in Canada at 2.5 to 5 percent. Go gently to avoid irritation, protect your towels, store it cool and replace it regularly. If your acne is severe, scarring or not improving after a couple of months, see your doctor.