Ingredient

Selenium Sulfide

A stronger anti-dandruff ingredient that also treats the patchy discoloration of tinea versicolor. It works, and it is unpleasant.
Dr. Schwarz, MD · Board-certified dermatologistLast reviewed September 8, 2026
Two Selsun Blue bottles, two Head and Shoulders Clinical Strength bottles and a Vichy Dercos bottle and box

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Selenium sulfide is what I reach for when gentler dandruff shampoos have failed, and my first choice for tinea versicolor — the pale or tan patches on the chest and back after a warm summer. For that it is genuinely good, cheap and easy to get. The problem is using it: a lingering metallic smell, coarse hair, and an orange tint on light, gray or color-treated hair. Contact time matters too — rinsed straight out it does nothing, and for tinea versicolor it has to sit on the skin.

— Dr. Schwarz, Board Certified Dermatologist

Key Facts

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Also calledSelenium disulfide, SeS2, selsun
TypeAntifungal. Also slows how fast skin cells are shed
Strengths sold1% over the counter. 2.25% and 2.5% by prescription
UseTwice a week for dandruff. Daily for a week, or weekly, for tinea versicolor
Time to work1 to 2 weeks for dandruff. 2 to 4 weeks for tinea versicolor, with color evening out over months
Prescription neededNo for 1%. Yes for 2.25% and 2.5%

What It Is

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Selenium sulfide is a compound of selenium and sulfur, sold as an orange-brown suspension. A medicated shampoo since the 1950s, and still standard for dandruff, seborrheic dermatitis and tinea versicolor. In the United States a 1% shampoo is over the counter; 2.25% and 2.5%, usually a lotion or a shampoo that can go on the body, are prescription. The stronger ones are used for tinea versicolor, where the area treated is the trunk rather than the scalp. It does not dissolve, so it settles in the bottle and needs shaking before use. That is also why it can leave a film or tint on hair and light-colored surfaces, and why rinsing thoroughly matters more here than with an ordinary shampoo.

How It Works

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Selenium sulfide works against Malassezia, the yeast that lives on everyone's skin and drives dandruff, seborrheic dermatitis and tinea versicolor. It disrupts the fungal cell and stops it growing; less yeast means less of the irritation behind the flaking and itch.

It also slows how fast skin cells divide and shed — a cytostatic effect, which most antifungals do not have. In a scalp shedding cells in visible clumps, slowing that down improves the appearance directly, whatever the yeast is doing. That is part of why it works when a purely antifungal shampoo has not.

Tinea versicolor confuses people most. The yeast makes substances that interfere with pigment production, leaving patches lighter or darker than the surrounding skin. Selenium sulfide clears the yeast within a couple of weeks, but the color takes far longer to even out, because skin makes or loses pigment at its own pace. The patches are not an active infection by then. They are a mark left behind.

Here is where Selenium Sulfide acts in the skin, and what the others do instead.

About Selenium Sulfide
Compare
Skin basics
BARRIEREPIDERMISDERMISPOREOILGLANDKILLS YEASTSTAYS ON THE SURFACESTOPS PLUGS FORMINGUNCLOGS THE POREKILLS BACTERIALOWERS OIL PRODUCTIONKILLS MITES

The yeast involved here lives on everyone's skin and only causes trouble when it overgrows in oil. Selenium Sulfide reduces it, which is why the flaking and itching settle and why it comes back if treatment stops for good. A wash-off that lowers yeast on the surface. Leave it on a few minutes.

Selenium sulfide stays in the outer layer and on the skin's oil, where the yeast grows.

Retinoids change how the lining of the pore sheds its cells, so the plug that starts a spot stops forming in the first place. That is why they prevent spots rather than treat the ones already there, and why the first weeks can look worse before they look better.

Salicylic acid dissolves in oil, so it gets down inside the pore rather than sitting on the surface, and loosens the plug of dead skin and sebum blocking the way out.

This works on the bacteria growing in an inflamed pore. Less bacteria means less for the immune system to react to, which is what takes the redness and soreness out of a spot.

This works upstream of the spot, on the gland itself. Less oil means fewer plugs, less for bacteria to feed on and less inflammation, which is why it changes the pattern rather than clearing one spot.

Everyone carries these mites in their follicles. In some people the immune system reacts to them, and reducing their number reduces the bumps and the redness that come with them.

The outer film of dead cells and oil. It holds water in and keeps irritants out, and it is thinner than a sheet of paper. Almost every dry, itchy, stinging skin problem starts here.

The outer layer, and the only one anything in a jar reaches. It renews itself constantly: a cell made at the bottom takes about a month to reach the surface and flake off. Most of what a skincare product does, it does here.

The living layer underneath, holding the blood vessels, the nerves and the collagen. It is where lasting change happens and it is hard to reach: most of what is sold for the skin never gets this far.

What It Treats

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Tinea Versicolor

Tinea Versicolor

Strong evidence

Just as effective as ketoconazole for this and usually cheaper, spread over the affected area, left on for five to ten minutes and washed off. It has a noticeable sulfur smell that lingers, and it can discolor fabric and light hair, so old clothes and a thorough rinse are worth planning for.

Dandruff

Dandruff

Strong evidence

Reduces the yeast and also slows how fast scalp cells shed, which makes it useful when the flaking is heavy. Rinse it thoroughly. The catch is color: it can discolor light, gray, relaxed or color-treated hair, so zinc pyrithione or ketoconazole is usually the better pick for those.

Close-up of light skin with a scattered cluster of small pink raised bumps, some with tiny white tips

Fungal Acne (Malassezia Folliculitis)

Moderate evidence

An anti-dandruff shampoo used the same way, lathered on the affected areas and left several minutes. A reasonable alternative if ketoconazole irritates or is hard to find. It can be drying and can discolor light-colored hair, so keep it on the body.

Seborrheic Dermatitis

Seborrheic Dermatitis

Moderate evidence

Another shampoo that reduces the same yeast by a different route, useful when ketoconazole has lost its edge. It works well on a thickly scaling scalp. It has a strong smell and can discolor light, gray or chemically treated hair, so rinse thoroughly and keep it off the length where you can.

Forms

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A 1% shampoo is over the counter; 2.25% and 2.5% are prescription, as a shampoo or a lotion for the body as well as the scalp. For tinea versicolor it goes on the skin, not the hair: applied to the affected area, left on for the time the label specifies, then rinsed. Two schedules are common: a short daily application for about a week, or a longer weekly one for several weeks.

A row of Selenium Sulfide products sold as shampoo, 1%, photographed on white.
Over the counter
Shampoo, 1%
For dandruff and seborrheic dermatitis. Left on a few minutes before rinsing.
A row of Selenium Sulfide products sold as prescription shampoo, photographed on white.
2.25% to 2.5%
Prescription shampoo
The stronger version, and the one used on the body for tinea versicolor.
A row of Selenium Sulfide products sold as lotion, photographed on white.
Body use
Lotion
Spread over the affected skin, left in place, then rinsed. Made for large areas.
A row of Selenium Sulfide products sold as foam, photographed on white.
Easier to spread
Foam
Available in some places. Kinder on hairy skin and quicker over a back.
A row of Selenium Sulfide products sold as two-in-one shampoo, photographed on white.
Convenient, and weaker
Two-in-one shampoo
The conditioner blocks deposit. Use a plain one if it is not working.

Strengths

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The gap between over-the-counter and prescription strength is about what you are treating, not how bad the dandruff is.

WeakestStrongest
1%2.25%2.5%
Over the counter
1%
The everyday dandruff strength, used twice a week. Enough for mild to moderate flaking.
Prescription
2.25%
An intermediate strength, sometimes better tolerated than 2.5% while doing much the same job.
Prescription
2.5%
For tinea versicolor and stubborn seborrheic dermatitis, and the one applied to the body rather than only the scalp.

Basics

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When to Apply
In the shower. For dandruff, twice a week — wet the hair, work it into the scalp, leave it two to three minutes, then rinse. For tinea versicolor, apply it to the affected skin, leave it on as the label specifies, and rinse off completely.
How to Start
Twice a week for two to four weeks for dandruff, then weekly or fortnightly to keep it settled. For tinea versicolor, finish the course rather than stopping when the itching goes — the yeast clears before the color does. Take off jewelry first, and rinse until the water runs clear.
If It Irritates
Dryness, an oily rebound, a metallic smell and coarse hair are the usual complaints, and they settle with less frequent use and conditioner on the lengths. Stinging, burning or a rash means stop. Never use it on broken, weeping or freshly shaved skin — it stings badly and more is absorbed.
If It’s Not Working
For dandruff, give it four weeks of correct use before switching; ketoconazole is the usual alternative. For tinea versicolor, the patches take months to blend back in even after successful treatment, so pale skin at four weeks is not failure. See a doctor if patches spread or new ones appear.

What to Expect

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Days 1 to 7Weeks 1 to 2Week 4Months 2 to 6
Adjusting
Days 1 to 7
Less itching. A metallic smell during and after use, and rougher hair. Flaking may not have changed yet.
Working
Weeks 1 to 2
Flaking and redness settle. In tinea versicolor, the fine scale disappears and the patches stop spreading.
Judge it here
Week 4
For dandruff, a fair point to decide. For tinea versicolor, judge the infection, not the color.
Color evening out
Months 2 to 6
The patches slowly blend back in. Sun makes the contrast more obvious meanwhile.

What to Avoid

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  • Cosmetic, not medical The trouble with it is nearly all avoidable.
  • Broken, raw or freshly shaved skin it stings sharply and more is absorbed. Wait until skin is intact.
  • Jewelry, especially silver take rings, chains and earrings off first — the sulfur tarnishes metal.
  • Leaving it in the hair incomplete rinsing causes the orange tint on light, gray, bleached or color-treated hair, and the lingering smell. Rinse until the water runs clear.
  • Using it on the face or near the eyes it is not made for facial skin and stings badly in the eyes. Facial seborrheic dermatitis is treated differently.
  • Assuming pale patches mean it failed in tinea versicolor the color returns last, and repeating treatment does not speed it up.

If You Stop

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Dandruff and seborrheic dermatitis return over two to four weeks, like any antifungal shampoo. The yeast is reduced, not removed, and it recolonizes from the surrounding skin. Tinea versicolor comes back more often than most skin infections, especially in warm, humid climates and in people who sweat heavily. Many people use it once or twice a month through the summer to prevent it. Recurrence does not mean the original treatment failed. Nothing to taper, no rebound. Hair texture and any tint from poor rinsing recover once you stop, though a tint on bleached or gray hair can take several washes to lift.

Ask Your Doctor

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If the patches keep spreading despite treatment: The diagnosis may not be tinea versicolor.
If your scalp is weeping, crusted or painful: That suggests infection or another condition.
If four weeks of correct use has not settled the flaking: A different antifungal or a prescription scalp treatment.
If you are treating a child
Strengths, contact times and the area treated differ in children. Do not improvise.
If your skin stings, burns or blisters
Stop and have it looked at rather than pushing on.
If you are pregnant or breastfeeding
Ask the doctor managing your pregnancy before using prescription strengths.

How It Compares

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Ketoconazole 1% or 2%

The same

Generally the better tolerated option for both dandruff and tinea versicolor. Selenium sulfide is cheaper and does not need a prescription at 1%.

Four dandruff shampoo bottles: DHS Zinc, Head and Shoulders Classic Clean, CeraVe Anti-Dandruff and Head and Shoulders Bare16:9 hero for Pyrithione Zinc. Never cropped: the tone strip and the corner logo depend on the full frame.

Pyrithione zinc

The same

Comparable evidence for dandruff and much more pleasant to use, with no smell and no risk of tinting hair. Selenium sulfide is stronger and does more for tinea versicolor.

Five medicated scalp products on white, including Amazon Basics tar gel, T+Plus, MG217, RoyceDerm and Nizoral16:9 hero for Coal Tar. Never cropped: the tone strip and the corner logo depend on the full frame.

Coal tar

Different job

Better for scalp psoriasis. Selenium sulfide is the better choice when the problem is yeast rather than psoriasis.

Oral antifungal tablets

Different job

For widespread or repeatedly returning tinea versicolor. More convenient, but they carry whole-body side effects that a rinse-off product does not.

Salicylic acid shampoo

Different job

It lifts scale but does not treat the yeast, so it works best combined with an antifungal rather than instead of one.

Myths

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  • "Tinea versicolor is a lack of pigment, so it needs a lightening or darkening cream." The patches come from a yeast interfering with pigment production. Treat the yeast and the color corrects itself. Creams for pigmentation do not help and can make the contrast worse.
  • "If the patches are still there, the treatment did not work." Clearance is the fine scale disappearing and the patches not spreading, not the color. Wait months rather than reaching for more shampoo.
  • "Selenium sulfide is dangerous because selenium is toxic." Selenium is toxic in large amounts swallowed over time. Used as directed on intact skin and rinsed off, very little is absorbed. The risk rises on broken skin or if it is left on far longer than instructed.
  • "It causes hair loss." It can make hair dry and coarse and tint light hair, and both get blamed for shedding. There is no good evidence it causes hair loss; untreated scalp inflammation is likelier.
  • "Tinea versicolor is contagious." The yeast already lives on almost everyone's skin. What differs is who reacts — heat, humidity, sweating and susceptibility, not catching it.

Questions Patients Ask

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Why are the pale patches still there after treatment?

Because the color recovers last. The yeast clears within a few weeks, but skin rebuilds or sheds pigment at its own pace, which takes two to six months. Sun makes it more obvious, because the surrounding skin tans and the patches do not.

Will it change my hair color?

It can leave an orange or brassy tint on light, gray, bleached or color-treated hair, usually when it is not rinsed out thoroughly. Rinse until the water runs clear.

How long do I leave it on?

Two to three minutes on the scalp for dandruff. For tinea versicolor, follow the label or your prescriber — the two schedules differ: a short daily application for about a week, or a longer one once a week.

Can I use it on my face?

No. It is not made for facial skin and it hurts in the eyes. Facial seborrheic dermatitis is treated with milder antifungal creams.

Is the smell normal?

Yes. It is a sulfur compound, so a metallic or eggy smell during and after use is expected. It fades once the hair is dry.

Does tinea versicolor come back?

Often, especially in hot, humid weather and in people who sweat heavily. That is not treatment failure. Many people use it once or twice a month through the summer.

References

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