Sulfur for Acne: How It Works and What the Evidence Says

Sulfur is one of the oldest acne ingredients still sold over the counter, allowed in US acne products at 3% to 10%. It has antibacterial, antifungal and peeling (keratolytic) activity, and it’s generally mild. The catch is evidence: the 2024 American Academy of Dermatology (AAD) guideline found there wasn’t enough good research to recommend it either way. It can be a reasonable gentle spot treatment, but it isn’t a substitute for better-studied options, and yes, it can smell.

What is sulfur, and how is it sold for acne?

Sulfur is a naturally occurring element that has been used on skin for a very long time. A 2004 review in the Journal of Drugs in Dermatology notes that its use was once widespread for acne, rosacea, seborrheic dermatitis, dandruff, scabies and warts.

In the US, sulfur is one of the few active ingredients allowed in OTC acne drugs under the FDA’s acne monograph. The rules permit sulfur at 3 to 10 percent on its own. The FDA’s updated OTC Monograph M006 also allows sulfur at 3% to 8% when combined with resorcinol or resorcinol monoacetate, the only combinations the monograph permits with sulfur. You’ll mostly see sulfur in spot treatments, masks, lotions and bar soaps. The Mayo Clinic lists sulfur creams, lotions, ointments and bar soaps as acne treatments.

There’s also a prescription-only relative: sodium sulfacetamide plus sulfur, which pairs sulfur with a sulfonamide antibiotic. More on that below.

How does sulfur work on acne?

According to the 2004 review, sulfur “has antifungal, antibacterial, and keratolytic activity.” In acne terms, that means it may help loosen the dead skin cells that clog pores and reduce the microbes involved in inflamed spots. A 2015 review in Cutis similarly describes sulfur’s “keratolytic, antibacterial, antifungal, and antiparasitic effects.”

That’s a reasonable mechanism on paper. But the details of how sulfur acts on skin are less well pinned down than for benzoyl peroxide or retinoids, and a plausible mechanism is not the same thing as proven results.

What does the evidence show?

Honestly, not much. When the AAD updated its guideline in 2024, the panel concluded, as reported by MDedge, that “available evidence is insufficient to develop a recommendation on the use of topical glycolic acid, sulfur, sodium sulfacetamide, and resorcinol for acne treatment.” That’s not a finding that sulfur doesn’t work. It means nobody has run the kind of trials needed to know how well it works.

Cochrane found a similar gap. A 2020 Cochrane review set out to assess six topical treatments, including sulfur, and included 49 trials with 3,880 participants. Its summary reports no sulfur-specific results, and the authors concluded that, beyond a couple of azelaic acid comparisons, the evidence was low or very low quality.

The strongest-sounding numbers come from the prescription combination. The Cutis review states that “twice-daily use of sodium sulfacetamide 10%–sulfur 5% for 12 weeks decreases inflammatory acne lesions by 80.4% to 83%.” Those figures come from two older studies published in 1993 and 1997, and I couldn’t confirm how rigorously they were controlled. They also can’t tell you how much is due to the sulfur versus the antibiotic.

Bottom line: sulfur’s evidence is very limited. For comparison, the 2024 guideline (Reynolds et al., JAAD) gives strong recommendations to benzoyl peroxide, topical retinoids, topical antibiotics and oral doxycycline, and a conditional one to salicylic acid. The AAD’s announcement describes topical retinoids as strongly recommended “to help unclog pores and reduce inflammation.”

What does that mean if you’re standing in a drugstore aisle choosing one product? If you have mostly red, inflamed pimples, benzoyl peroxide is the better-supported pick. If you have mostly blackheads and whiteheads, adapalene or salicylic acid make more sense. Sulfur fits best as an add-on spot treatment for the occasional pimple, or as an option to discuss with a clinician if other products don’t suit your skin. None of that rules sulfur out; it just means you’re working with less information.

When might sulfur make sense?

Given the thin evidence, I’d think of sulfur as a supporting player. Situations where people reasonably reach for it:

• An occasional spot treatment for mild breakouts. The OTC label itself directs you to “apply only to areas with acne.”
• If you want something that doesn’t bleach fabric. Benzoyl peroxide bleaches towels and pillowcases; sulfur doesn’t carry that label warning.
• When a clinician suggests it. Prescription sulfacetamide-sulfur is used for acne and, per the AAD, for rosacea’s acne-like breakouts, particularly in people who also have seborrheic dermatitis.

Because sulfur has antifungal activity, you’ll sometimes see it suggested for “fungal acne” (Malassezia folliculitis). That’s a different condition from acne with its own treatments; see my guide to fungal acne before assuming sulfur is the answer.

If your acne is more than a few spots, you’ll likely get further with a better-supported routine, such as benzoyl peroxide or adapalene (Differin), as laid out in my simple acne routine.

How to use sulfur

The FDA monograph’s standard directions for OTC acne products are to “cover the entire affected area with a thin layer one to three times daily,” starting with once a day. For sulfur specifically, the labeling adds:

• Don’t use it on broken skin or large areas of skin, per the sulfur-specific warning.
• Apply only to areas with acne, rather than all over your face.
• Don’t stack it with other drying treatments. The monograph warns that irritation and dryness are more likely if you use another topical acne medicine at the same time. The Mayo Clinic advises against using sulfur together with benzoyl peroxide, salicylic acid or other peeling agents unless your doctor says so, and the tretinoin prescribing information says to avoid using tretinoin at the same time as preparations containing sulfur.
• Give it time, then reassess. The AAD suggests giving any acne treatment six to eight weeks.

Side effects, smell and who should avoid sulfur

Irritation. The 2004 review says side effects from topical sulfur “are rare and mainly involve mild application site reactions.” The Mayo Clinic lists redness and peeling as expected effects, and new skin irritation as a reason to check with your doctor.

The smell. Sulfur products have a reputation for an unpleasant odor. The Cutis review says the “offensive smell” of sulfur preparations has historically limited how consistently people use them, though newer formulations are designed to reduce it. Many people use sulfur at night for this reason.

Mercury-containing products. The Mayo Clinic warns that using sulfur with mercury-containing skin products may cause a foul odor, irritate the skin and stain it black.

Sulfa allergy and the prescription combination. Sodium sulfacetamide-sulfur labels list hypersensitivity to sulfonamides, sulfur or any other component as a contraindication and say it shouldn’t be used by people with kidney disease. The label I checked also states that the product has “not been found by FDA to be safe and effective.” If you have a sulfa drug allergy, tell your prescriber.

Pregnancy and breastfeeding. I couldn’t find clear sulfur-specific guidance from the AAD or MotherToBaby. The Mayo Clinic notes there are no adequate studies on infant risk during breastfeeding, and the prescription sulfacetamide-sulfur label advises use in pregnancy “only if clearly needed.” Ask your obstetrician or dermatologist before using it.

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