Sulfur for acne: what it does and how to use it

Sulfur is one of the acne ingredients the FDA allows in products sold without a prescription. It shows up in masks, spot products, ointments and washes. This guide explains what the FDA allows, what the labels tell you to do, what the smell and dryness are like, and where sulfur sits next to benzoyl peroxide and salicylic acid. It is part of the guide on how to get rid of acne.

What the FDA allows in a sulfur acne product

In the US, an acne product sold without a prescription has to follow the FDA's acne monograph. A monograph is a fixed set of rules: it lists the active ingredients a product may use, the strength of each one, and the warnings and directions that must be printed on the label. Sulfur appears on that list on its own and in two combinations.

What the product contains	Strength the FDA allows	What the label must add
Sulfur on its own	3 to 10 percent sulfur	Apply only to areas with acne. Do not use on broken skin or large areas of skin
Sulfur with resorcinol	3 to 8 percent sulfur, with 2 percent resorcinol	The sulfur warnings, plus: rinse right away with water if it gets in the eyes, and stop and ask a doctor if irritation starts or gets worse
Sulfur with resorcinol monoacetate	3 to 8 percent sulfur, with 3 percent resorcinol monoacetate	The same as sulfur with resorcinol

The active ingredient and its strength are printed in the Drug Facts box. If a box lists "Sulfur 10%" under "Active ingredient", the product is sold as an acne drug under these rules. MedlinePlus, the US National Library of Medicine's health site, lists sulfur and resorcinol among the ingredients found in acne products sold without a prescription. The full list of allowed ingredients is in the guide to over-the-counter acne treatments.

Every over-the-counter acne label under the FDA's rules says to cover the entire affected area with a thin layer. Sulfur labels add two lines that no other acne ingredient gets: apply only to areas with acne, and do not use on broken skin or large areas of skin. Those lines suit small areas, which is how masks and spot products are used.

How sulfur works on acne

A prescription sodium sulfacetamide and sulfur wash label on DailyMed, the US National Library of Medicine's database of drug labels, says the exact way sulfur acts on acne is unknown. The same label says sulfur has been reported to slow the growth of the bacteria linked to acne and the forming of free fatty acids.

The American Academy of Dermatology (AAD) describes one more effect: sulfur can remove the top layer of skin. The prescription label says the aim of this treatment is to make the skin peel without irritating it.

How well sulfur works is a harder question. The AAD's 2024 acne guideline, written by a panel of dermatologists who reviewed the published studies, looked at sulfur, sodium sulfacetamide and resorcinol. It found the evidence insufficient to make any recommendation on them for acne. For comparison, the same guideline gave strong recommendations to benzoyl peroxide, topical retinoids such as adapalene, and topical antibiotics.

How to use a sulfur mask, spot product or wash

Every over-the-counter acne product carries the same basic directions, set by the FDA:

1. Clean the skin well before you apply the product.
2. Start with one application a day, because the skin can become too dry.
3. If your skin handles it, go up to two or three times a day, or follow a doctor's directions.
4. If dryness or peeling bothers you, cut back to once a day or every other day.

Products that go on and then come off, such as masks and washes, may add their own directions. The FDA's acne rules name soaps and masks as examples. Two labels on DailyMed show how much these directions differ:

• A 10 percent sulfur ointment says to put a thin layer over the affected area, leave it on for 10 minutes, then remove it well with water.
• A 3.5 percent sulfur mask says to massage it into clean, wet skin for two to three minutes, leave it on for 10 more minutes until it dries, then rinse with warm water. It gives a schedule of two to three times a week.

So read your own product's Drug Facts box before the first use. The time on the skin and the number of uses per week are printed there.

The FDA also allows an optional sensitivity test on acne labels. You apply a small amount to one or two small areas with acne for the first 3 days. If there is no discomfort, you follow the normal directions. It is a sensible way to start any sulfur product, since sulfur can irritate.

One rule applies to every acne product. The FDA label says irritation and dryness are more likely if you use another acne medicine on the skin at the same time. If irritation starts, use only one acne medicine at a time.

Smell, dryness and other side effects

The smell

Sulfur products can smell of sulfur. A 2009 review in the Journal of Clinical and Aesthetic Dermatology describes a newer foam version of sulfur with sodium sulfacetamide that has a weaker sulfur smell than older versions. The author of that review disclosed paid work for drug companies, including companies that sell acne products. The same review says sulfur with sodium sulfacetamide has been used on the skin since the mid-1950s.

Dryness and irritation

Dryness is the side effect the FDA writes into every acne label. The AAD also names sulfur, together with benzoyl peroxide, as an acne ingredient that can increase skin irritation and dryness. The AAD gives this warning to people taking isotretinoin, a prescription acne pill, and advises them to avoid sulfur products during treatment.

The prescription sulfur label adds that sulfur and sodium sulfacetamide can cause redness and scaling of the skin. If irritation develops, that label says to stop the product and get the right treatment.

Silver and fabric

One sulfur mask label says to keep the product away from silver jewelry, which it may discolor. The FDA requires its bleaching warning ("may bleach hair and dyed fabrics") on benzoyl peroxide products only.

Sulfur with sodium sulfacetamide, by prescription

Some sulfur products need a prescription. The prescription washes on DailyMed that this guide checked pair sulfur with sodium sulfacetamide, an antibiotic from the sulfonamide family (the "sulfa" drugs). One wash on DailyMed contains 10 percent sodium sulfacetamide and 5 percent sulfur. Its label lists three uses: acne, the acne-like bumps of rosacea, and seborrheic dermatitis, a condition that causes flaky, red patches on oily areas of the skin.

That label says the wash is used once or twice a day, massaged into wet skin for 10 to 20 seconds and then rinsed off. It also says who should not use it:

• people allergic to sulfonamides, to sulfur or to any other ingredient in it,
• people with kidney disease.

The label warns that rare but serious allergic reactions, including Stevens-Johnson syndrome, have been reported after sodium sulfacetamide was used on the skin. It also carries this FDA statement: the FDA has not found the drug safe and effective, and has not approved its label.

One more detail matters if you also use benzoyl peroxide. The 2024 AAD guideline says that putting benzoyl peroxide on at the same time as sulfacetamide turns the skin orange-brown. The color washes off. If you use both, ask the doctor who prescribed them when to apply each one.

The AAD's rosacea page says dermatologists sometimes prescribe a sulfacetamide and sulfur lotion for the acne-like bumps of rosacea. If the rosacea gets worse or a rash appears, the AAD says to stop the medicine and call your dermatologist right away. Rosacea and acne can look alike, and the guide to rosacea vs acne explains how doctors tell them apart.

How sulfur compares with benzoyl peroxide and salicylic acid

	Sulfur	Benzoyl peroxide	Salicylic acid
Strength sold without a prescription	3 to 10 percent	2.5 to 10 percent	0.5 to 2 percent
2024 AAD guideline rating	Not enough evidence to rate	Strong recommendation	Conditional recommendation
Extra FDA label warning	Apply only to areas with acne. Keep off broken skin and large areas	May bleach hair and dyed fabrics. Use sunscreen	None beyond the standard acne warnings

In the guideline's own terms, a strong recommendation means the benefits clearly outweigh the risks and burden, and it applies to most patients. A conditional recommendation means the benefits are closely balanced with the risks and burden.

Benzoyl peroxide has the most support of the three. The AAD suggests starting with a 2.5 percent product, and Skinli's starting plan uses benzoyl peroxide 2.5 percent with adapalene 0.1 percent. The guide to benzoyl peroxide covers how to start it. Salicylic acid helps unclog pores, and the AAD says it works best on blackheads and whiteheads. The guide to salicylic acid vs benzoyl peroxide compares those two in detail.

Who might choose sulfur

None of the medical sources used for this guide names a group of people for whom sulfur is the best choice. Here is what the sources say about two groups of people who may look at sulfur:

• People who react to benzoyl peroxide. The FDA requires benzoyl peroxide labels to say do not use if you are sensitive to benzoyl peroxide. Sulfur and salicylic acid are the other single ingredients allowed in over-the-counter acne products, and adapalene 0.1 percent gel is sold without a prescription under its own FDA approval. A person who cannot use benzoyl peroxide still has these options.
• People with sensitive skin. The AAD lists sulfur with benzoyl peroxide as ingredients that can increase irritation and dryness. If your skin reacts to most products, start sulfur once a day on a small area, or use the sensitivity test on the label.

A product used only on a few spots fits best on skin that is usually clear. For regular breakouts, the guide to acne spot treatment explains why the AAD advises spreading acne medicine over all acne-prone skin.

How long to give it, and when to see a doctor

The AAD advises using one acne product for 6 to 8 weeks before you judge it, without adding or stopping products during that time. Skinli's guides and plan allow 8 to 12 weeks for skin to change.

See a doctor, or a dermatologist, if any of these apply:

• You have large, painful pimples deep in the skin, or acne that leaves scars. The AAD says these need a dermatologist.
• You are pregnant or trying to get pregnant. The AAD says to consult a dermatologist before you treat acne on your own.
• Your skin swells, blisters or becomes painful after using a product.
• You have tried sulfur or another product for several months with no change.

Sulfur is an allowed acne ingredient with limited proof behind it. Used on a few spots, once a day at first, it is a reasonable thing to try. For acne that covers large areas or keeps coming back, benzoyl peroxide and adapalene have stronger evidence, and a dermatologist has stronger medicine.