Benzoyl peroxide: what it does and how to use it

Benzoyl peroxide is an acne medicine that kills the bacteria that make pimples red and swollen. It is sold in U.S. stores without a prescription at 2.5% to 10%, and it is part of several prescription acne gels. The American Academy of Dermatology (AAD) calls it "one of the most effective and commonly used acne treatments," and its 2024 acne guideline gives it a "strong" recommendation. This guide covers what benzoyl peroxide is, how it works, what the evidence shows, how to use it, and what to know about side effects, bleaching, benzene and pregnancy. Each topic has its own detailed guide in this section.

Skinli gives general education. A doctor or pharmacist is the right person to diagnose and treat your skin. Deep, painful acne and acne that leaves scars need a doctor.

What benzoyl peroxide is

The NHS describes it as "an antiseptic medicine that's used to treat acne," one that "works by reducing the amount of bacteria on your skin and helps improve symptoms such as spots and blocked pores (blackheads and whiteheads)." The prescription labels describe it as "an oxidizing agent with bactericidal and keratolytic effects." In plain words, it is a reactive chemical that kills bacteria and loosens dead skin cells. The labels add that "the precise mechanism of action is unknown."

In the U.S., the FDA regulates store acne products under a rule known as the acne monograph, 21 CFR Part 333. A final rule published on March 4, 2010 added benzoyl peroxide as a "generally recognized as safe and effective" active ingredient for store acne products and set the warnings every label must carry. The rule allows "benzoyl peroxide, 2.5 to 10 percent."

How it works on acne

Acne has several causes: oil, clogged pores, bacteria and inflammation. Benzoyl peroxide works mainly on the bacteria. The AAD says it "reduces acne-causing bacteria on your skin," and lists what each acne ingredient targets: "Benzoyl peroxide decreases P. acnes bacteria," while "retinoids, such as adapalene gel, unclog pores and reduce oiliness."

The effect on bacteria comes fast. A 1986 study found a 2.5% gel lowered acne bacteria within 2 weeks. A 2018 study found a 5% gel cut acne bacteria by 89% after 1 week.

Benzoyl peroxide kills bacteria in a different way from antibiotics, and that matters. A 2008 study found a 6% benzoyl peroxide cleanser lowered acne bacteria that resisted erythromycin, tetracycline and clindamycin just as much as bacteria that did not. The AAD says that when an antibiotic applied to the skin is part of an acne plan, "you'll use it along with an acne medication or wash that contains benzoyl peroxide. Doing so reduces your risk of developing antibiotic resistance."

Because it works mainly on bacteria, the AAD says benzoyl peroxide is "most effective when used along with another acne treatment that works on the other causes of acne." That is why it is so often paired with a retinoid.

What the evidence shows

Source	What it says about benzoyl peroxide
AAD acne guideline, 2024	"Strong recommendations are made for benzoyl peroxide, topical retinoids, topical antibiotics, and oral doxycycline"
NICE, England	First-choice options include adapalene with benzoyl peroxide "for any acne severity" and benzoyl peroxide with clindamycin "for mild to moderate acne"; benzoyl peroxide alone is an alternative
1986 trial, 153 people	2.5% beat a gel without medicine and matched 5% and 10% on red pimples, with less irritation than 10%
2017 trial, 609 people	Red pimples fell by a median of 72.7% with 2.5% gel and 75.0% with 5% gel over 12 weeks, against 41.7% without medicine
2025 survey of 62 cosmetic dermatologists	Agreed on benzoyl peroxide for acne and for oily skin

The 2017 trial was paid for by Maruho, the drug company that supplied the gels. The prescription gel labels also report benzoyl peroxide used alone, as a comparison: in one 12-week trial, 2.5% benzoyl peroxide cut red pimples by 49.3%, against 34.5% with a gel without medicine.

The before and after guide sets out what trials measured week by week.

What it treats

The FDA rule allows store products to say they are "for the treatment of acne" and that they reduce the number of acne blemishes, pimples, blackheads or whiteheads. Benzoyl peroxide does the most for red, inflamed pimples and pus bumps. For blackheads and whiteheads, the AAD suggests adding a retinoid, and for deep nodules and cysts, a dermatologist.

The AAD also says benzoyl peroxide is "found in medications used to treat rosacea and hidradenitis suppurativa," and it suggests benzoyl peroxide washes for hidradenitis suppurativa and for bumps at the back of the neck. Its use on folliculitis, an infection of the hair follicles, has little trial evidence; the folliculitis guide sets out what is known.

How it compares with other store ingredients

The AAD's page on treating adult acne at home lists four active ingredients dermatologists recommend for mild to moderate acne, and says what each does best:

Ingredient	What the AAD says it does	2024 AAD guideline
Benzoyl peroxide	"Especially effective at treating mild pimples"	Strong recommendation
Adapalene, a retinoid	"Helps to clear blackheads, whiteheads, and pimples"	Strong recommendation for retinoids applied to the skin
Azelaic acid	"Fights acne and can also fade the dark spots that appear when an acne spot clears"	Conditional recommendation
Salicylic acid	"Unclogs pores and exfoliates the skin," working "best on whiteheads and blackheads"	Conditional recommendation

The same page gives a rule for starting any of them: "Use that product for 6 to 8 weeks, taking care to use the product as directed on the instructions. During this time, don't add another product." Skinli's guide to salicylic acid vs benzoyl peroxide compares the two most common store choices in detail.

Who it suits

• Teenagers and adults with red pimples. The NHS says most adults and children aged 12 or older can use it.
• Skin of color. The AAD says a retinoid with benzoyl peroxide "works well in skin of color," and advises starting with 2.5% because stronger products "can cause dryness and flaking, which can worsen acne."
• People taking an antibiotic for acne. The AAD says dermatologists "include another medication like benzoyl peroxide" when they prescribe an antibiotic, to lower the risk of resistance.

It suits people less well if they are sensitive to it, have highly sensitive skin, or have broken or infected skin. The FDA label says not to use it if you "are sensitive to benzoyl peroxide," and the NHS says it may not be suitable if you have a skin infection or "broken skin, cuts or grazes."

Common mistakes

1. Starting too strong. The AAD advises 2.5%. A 1986 study found 10% cleared no more red pimples and caused more irritation.
2. Using too much. The NHS says more "will not mean the medicine works faster and can increase the risk of side effects."
3. Treating only the pimples you can see. The FDA label says to cover "the entire affected area."
4. Starting several products at once. The label warns that irritation is more likely with two acne medicines at the same time.
5. Stopping too early. The AAD says treatment takes "at least 6 to 8 weeks" to show fewer breakouts.
6. Skipping moisturizer and sunscreen. The AAD recommends a daily moisturizer, and the label asks for sunscreen.

Strengths and forms

Choice	Options	What the evidence says	Guide
Strength	2.5% to 10% in stores	2.5% cleared red pimples as well as 10% with less irritation	Strengths
Leave-on form	Gel, cream, lotion	No trial showed one clearing acne better; a water-based gel irritated less than an alcohol-based one	Cream or gel
Rinse-off form	Wash, cleanser, bar	Works when left on long enough; a quick rinse did less	Face wash
Prescription	Combined with clindamycin or a retinoid	In one 12-week trial, the combined gel beat each part alone on every measure	Clindamycin and benzoyl peroxide

The AAD advises starting with 2.5%: "While you'll find products that contain up to 10% benzoyl peroxide, it's best to start with a product that contains 2.5%. That will help you avoid side effects like dry, irritated skin or a burning sensation."

How to use it

The FDA label directions for leave-on products:

1. "Clean the skin thoroughly before applying this product."
2. "Cover the entire affected area with a thin layer one to three times daily."
3. "Start with one application daily, then gradually increase to two or three times daily if needed or as directed by a doctor."
4. "If bothersome dryness or peeling occurs, reduce application to once a day or every other day."
5. "If going outside, apply sunscreen after using this product."

Skinli's 12-week plan puts this into a routine. At night: wash with a gentle face wash, wait until the face is fully dry, spread a pea of benzoyl peroxide 2.5% gel over the whole area that gets pimples, wait 5 minutes, apply adapalene 0.1% gel, then moisturizer. Start every other night for 2 weeks, then every night. In the morning: face wash, moisturizer and sunscreen SPF 30. For sensitive skin, the plan washes the gels off after 1 hour for the first 2 weeks, which follows NICE's advice to "start with alternate-day or short-contact application."

Before using a new benzoyl peroxide product for the first time, the FDA encourages this test: "apply a small amount to one or two small affected areas of the skin for 3 days." If no discomfort occurs, follow the label.

Moisturizer helps. The AAD lists benzoyl peroxide among treatments that "tend to dry and irritate the skin" and says "using a moisturizer every day can help your skin tolerate these medications." The moisturizer guide covers the order and what the studies on ceramide moisturizers found.

For a single pimple, a leave-on product can also be used as a spot treatment; Skinli's guide to acne spot treatment covers that use. For a full beginner routine, see start an acne routine with three products.

Using it with other ingredients

Every store label warns: "skin irritation and dryness is more likely to occur if you use another topical acne medication at the same time. If irritation occurs, only use one topical acne medication at a time." Some pairings are standard and planned; others add irritation without clear benefit.

Pairing	Where to read more
Adapalene, tretinoin or retinol	A retinoid with benzoyl peroxide
Salicylic acid	Salicylic acid vs benzoyl peroxide
Vitamin C	Benzoyl peroxide with vitamin C
Clindamycin (prescription)	Clindamycin and benzoyl peroxide

For a wider comparison of store products, see Skinli's guide to over-the-counter acne treatments.

Side effects

The label lists the common ones: "skin irritation may occur, characterized by redness, burning, itching, peeling, or possibly swelling." The NHS says these "usually improve after a few days, or if you use the gel or gel wash less often." In the 2017 trial, side effects occurred in 56.4% of people on 2.5% gel, all mild or moderate. Benzoyl peroxide also makes skin more sensitive to the sun: the label says to "avoid unnecessary sun exposure and use a sunscreen."

Early redness and peeling are sometimes called purging. Benzoyl peroxide labels list irritation as the early side effect; the purging guide explains the difference, and Skinli's guide to purging vs a breakout covers the retinoids that do cause purging.

Serious allergic reactions are rare but real. In 2014, the FDA warned that store acne products with benzoyl peroxide or salicylic acid "can cause rare but serious and potentially life-threatening allergic reactions." Stop using the product and get emergency help right away for throat tightness, trouble breathing, feeling faint, or swelling of the eyes, face, lips or tongue. The safety guide covers these signs.

Bleaching

Every label must say: "avoid contact with hair and dyed fabrics, which may be bleached by this product." It bleaches towels, pillowcases, clothes and hair. The AAD says the worry that it causes light spots on the skin is "a myth." Skinli's plan tells anyone starting it to use a white towel and pillowcase. The bleaching guide covers the details.

Benzene and storage

Benzoyl peroxide can break down into benzene, a chemical that can cause cancer, especially when products get hot or are stored a long time. On March 11, 2025, the FDA reported testing 95 benzoyl peroxide acne products: more than 90% had no detectable benzene or only the smallest amounts, and six had elevated levels and were recalled from stores. The FDA said the cancer risk from the benzene found in those products was low, even with daily use for decades. The AAD says studies published in its journal found regular use of benzoyl peroxide acne products "not linked to an increased risk of developing cancer," while noting that "current research on this topic is limited."

The AAD's storage advice:

• Store products "at room temperature or cooler (e.g., refrigerated)."
• "Replace products that contain benzoyl peroxide every 10-12 weeks."
• "Throw out products exposed to higher temperatures (e.g., greater than 78°F)."

The FDA also recommends that consumers "throw away products that are beyond their expiration date." The safety guide gives the full timeline.

Pregnancy, breastfeeding and children

The AAD says experts consider benzoyl peroxide "safe to use in limited amounts" during pregnancy, and advises talking with your obstetrician or dermatologist first. The NHS says it "can usually be used during pregnancy, but it's best to check," and that during breastfeeding you should check with a pharmacist or doctor and avoid putting it on your breasts. The NHS says most adults and children aged 12 or older can use it. MedlinePlus says not to use it on children under 12 without talking to a doctor.

Scars and dark marks

Benzoyl peroxide prevents new scars by clearing acne. No trial Skinli found shows it fading scars or dark marks you already have. The AAD advises treating acne early to prevent dark spots and scars, and names azelaic acid and retinoids for the marks. Trials of a prescription gel combining adapalene and benzoyl peroxide found fewer new scars than a gel without medicine. The acne scars guide covers the trials, and Skinli's acne scar treatment guide and tretinoin for acne scars cover what treats existing scars.

Body acne

A 2012 study says benzoyl peroxide washes are commonly used on the back and chest, because they are easy to use on a large area and help avoid bleaching fabric. Skinli's guide to acne body wash explains how to use one on the back and chest, and the body acne guide covers acne on the rest of the body.

How long it takes

The NHS says benzoyl peroxide "usually starts to work within 4 weeks," and to speak to a pharmacist or GP if acne "does not improve after 12 weeks." The AAD says acne treatment takes "at least 6 to 8 weeks before you start to see fewer breakouts." Skinli's plan counts pimples on day 1, day 14 and every 2 weeks after, and judges results at week 8 against day 1.

When to see a doctor

See a doctor or dermatologist if your acne is deep or painful, leaves scars or dark marks, or has not improved after 12 weeks of steady use. A doctor can prescribe combination gels, oral medicines or other treatments. Stop and get emergency help for signs of a serious allergic reaction. For a plan built from a photo of your skin, try the free Skinli acne plan, or see a sample plan first. Skinli gives general education. A doctor is the right person to diagnose and treat your skin.