Ingredient

Pyrithione Zinc

The world's most common anti-dandruff ingredient. It slows the yeast behind the flaking and is mild enough for long-term use.
Dr. Schwarz, MD · Board-certified dermatologistLast reviewed September 8, 2026
Four dandruff shampoo bottles: DHS Zinc, Head and Shoulders Classic Clean, CeraVe Anti-Dandruff and Head and Shoulders Bare

Start here

If you have ever bought a dandruff shampoo, you have almost certainly used this — it is the ingredient in the blue bottle, and for straightforward dandruff it is a sensible place to start. The mistake I correct most often is how it is used; people lather, rinse and wonder why nothing happened. This is a medicine for the scalp, not a cleaner for the hair, so it has to sit on the skin for a few minutes before you rinse, and be used two or three times a week rather than whenever the flaking returns. It also has a ceiling — if four weeks of proper use has not settled things, I move to a different antifungal, usually ketoconazole, and stubborn seborrheic dermatitis often needs a short course of a prescription scalp treatment alongside it.

— Dr. Schwarz, Board Certified Dermatologist

Key Facts

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Also calledZinc pyrithione, ZPT, pyrithione zinc, zinc omadine
TypeAntifungal and antibacterial. Used mainly for dandruff and seborrheic dermatitis
Strengths sold1% and 2% in shampoos. Lower amounts in body washes, bar soaps and leave-on creams
UseTwo or three times a week, left on the scalp for several minutes before rinsing
Time to work1 to 2 weeks for flaking, about 4 weeks to judge it
Prescription neededNo

What It Is

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Pyrithione zinc is a zinc compound developed in the mid-twentieth century and used in shampoos since the 1960s. It is the ingredient behind most familiar anti-dandruff brands, which makes it among the most widely used medicated skincare ingredients in existence. It barely dissolves in water, so it sits in shampoo as a fine suspension. That is why those shampoos look opaque and need shaking, and why the product has to stay on the scalp a few minutes to deposit anything. Regulation differs by country, worth knowing before you shop abroad. In the United States it remains an approved over-the-counter ingredient for dandruff and seborrheic dermatitis. The European Union reclassified it and banned it from cosmetic products, including anti-dandruff shampoos, from March 2022, so European shelves carry other antifungals. That decision rested on laboratory toxicity classification, not reports of harm in people using shampoo.

How It Works

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Dandruff and seborrheic dermatitis are driven by Malassezia, a yeast that lives on everyone's scalp. It feeds on skin oils and releases free fatty acids, and in people whose skin reacts to those byproducts the result is inflammation, itch and the fast, untidy shedding that shows up as flakes. Reduce the yeast and the flaking settles.

Pyrithione zinc interferes with the yeast's handling of metals. It drives copper inside the fungal cell past what the cell can manage, damaging the iron-sulfur clusters its energy-producing enzymes depend on, and growth stops. The same mechanism works on a range of bacteria.

There is a smaller second effect. Zinc has a mild anti-inflammatory action on the scalp, and pyrithione zinc slows the overactive cell turnover of seborrheic dermatitis. So flaking improves partly because there is less yeast and partly because skin sheds more tidily.

Here is where Pyrithione Zinc acts in the skin, and what the others do instead.

About Pyrithione Zinc
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. Pyrithione Zinc reduces it, which is why the flaking and itching settle and why it comes back if treatment stops for good. The gentlest of the wash-off options, and the usual starting point.

Zinc pyrithione is a particle that stays on the surface and in the outer layer, which is where the yeast is.

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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Dandruff

Dandruff

Strong evidence

The workhorse dandruff shampoo: it reduces the yeast and calms the scalp, and it is gentle enough to keep using for years. Part the hair, work it into the skin rather than the lengths, and leave it on for five minutes. It is a good choice for color-treated, gray or relaxed hair because it does not discolor.

Seborrheic Dermatitis

Seborrheic Dermatitis

Moderate evidence

The active ingredient in most ordinary anti-dandruff shampoos, and a reasonable choice for scalp flaking without much inflammation. It is gentler and easier to use often than ketoconazole. If it has stopped helping, rotating to a different active ingredient usually works better than looking for something stronger.

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

The gentlest of the three anti-dandruff washes, and the easiest to keep using long term. It is a good choice for maintenance once the bumps have cleared, once or twice a week through the hot months. It is usually a little weaker than ketoconazole for clearing an active crop.

Tinea Versicolor

Tinea Versicolor

Moderate evidence

A gentler wash, better suited to keeping this away than to clearing a flare. It is the one most people find easy enough to keep using twice a month right through the summer, which is the part that actually prevents the next episode. On a widespread flare it is slower than ketoconazole or selenium sulfide.

Not the Best For

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Scalp Psoriasis

Scalp Psoriasis

Limited evidence

The active ingredient in most ordinary anti-dandruff shampoos. It is gentler than coal tar and can settle light flaking, but it was designed for the yeast behind dandruff rather than for psoriasis. If patches are thick or sharply bordered, this is not the one to keep trying.

Forms

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Pyrithione zinc is a shampoo ingredient first and everything else second, sold at 1% or 2%; the higher strength is worth looking for. Body washes and bar soaps carry it for seborrheic dermatitis on the chest and back and for the itchy uniform bumps often called fungal acne. Leave-on creams for facial seborrheic dermatitis exist at lower strengths but are hard to find.

A row of Pyrithione Zinc products sold as shampoo, photographed on white.
The main form
Shampoo
1% or 2%, left on the scalp a few minutes before rinsing. Start here.
A row of Pyrithione Zinc products sold as body wash, photographed on white.
Chest, back and shoulders
Body wash
Lathered on and left a minute. The usual choice for fungal acne.
A row of Pyrithione Zinc products sold as bar soap, photographed on white.
Cheap and simple
Bar soap
The same idea in a bar. Easy to use on the body, drying on the face.
A row of Pyrithione Zinc products sold as leave-on cream, photographed on white.
Facial seborrheic dermatitis
Leave-on cream
Lower strength, stays on the skin. Harder to find, and it does more.
A row of Pyrithione Zinc products sold as two-in-one shampoo, photographed on white.
Convenient, and weaker
Two-in-one shampoo
The conditioner gets in the way. Use a plain medicated shampoo if it stalls.

Strengths

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The range is short and the gap between the two shampoo strengths is modest. Contact time and frequency matter more than the number.

WeakestStrongest
0.1% to 0.25%1%2%
Leave-on
0.1% to 0.25%
The amount in creams and lotions that stay on the skin, for face and body rather than scalp.
Over the counter
1%
The strength in most everyday anti-dandruff shampoos. Enough for mild to moderate flaking two or three times a week.
Over the counter
2%
The strongest sold. Worth moving to if 1% has not settled things after a month, though the gain is small.

Basics

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When to Apply
In the shower, two or three times a week. Wet the hair, work it into the scalp rather than the lengths, and leave it on the skin three to five minutes before rinsing. Body washes the same way on chest, back and shoulders.
How to Start
Two or three times a week for the first month, with a normal shampoo in between if you wash daily. Once the flaking settles, most people drop to once or twice a week to keep it there. Stopping entirely is what brings it back.
If It Irritates
The usual complaint is dry scalp and dry hair rather than true irritation. Condition the lengths, cut contact time to three minutes, or drop to twice a week. Real itching, redness or a rash where the product runs means stop and consider allergy.
If It’s Not Working
Give it four weeks of proper use, with the shampoo actually left on the scalp. If nothing changes, switching antifungal beats increasing strength — ketoconazole and selenium sulfide work differently and often succeed where this has not. Thick, stuck-down scale or redness spreading past the hairline is worth a doctor's opinion.

What to Expect

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Days 1 to 7Weeks 1 to 2Week 4
Adjusting
Days 1 to 7
Less itching, often within the first few washes. Flaking may look no better; hair can feel drier.
Working
Weeks 1 to 2
Visible flaking drops, redness under the hair settles. Most improvement happens here.
Judge it here
Week 4
If flaking and itch are unchanged after a month of correct use, switch antifungal.
Ongoing | Maintenance
Once or twice a week indefinitely. Dandruff is controlled, not cured; it returns within a few weeks of stopping.

What to Avoid

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  • Very few conflicts Pyrithione zinc fits alongside almost anything else.
  • Rinsing it out immediately the most common reason it fails. It needs a few minutes on the scalp to deposit anything.
  • Two-in-one shampoo and conditioner the conditioning agents cut how much active reaches the scalp.
  • Scratching and picking at scale it damages the skin, drags out the inflammation, and can turn a flaking scalp into an infected one.
  • Heavy oils and styling products between washes, they feed the yeast causing the problem.
  • Using it only when the flaking returns this ingredient controls rather than cures, and stop-start use gives a stop-start result.

If You Stop

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Flaking and itching come back, usually within two to four weeks. Treatment reduces the yeast rather than eliminating it, and it recolonizes from the surrounding skin as soon as the pressure comes off. This is not a rebound. The scalp returns to its own baseline, and restarting works as well as it did the first time. Most people settle on maintenance instead of stopping: once or twice a week indefinitely, sometimes rotating with another antifungal shampoo. No known problem with long-term use.

Ask Your Doctor

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If four weeks of correct use has changed nothing: Another antifungal or a prescription treatment is next.
If the scalp is weeping, crusted or painful: Those suggest infection or another condition.
If redness and scale spread onto the face, ears or chest: Wider seborrheic dermatitis is treated differently.
If you are losing hair in patches
Patchy hair loss needs a diagnosis, not a shampoo.
If a baby has thick scale on the scalp
Cradle cap is managed differently, and not with medicated shampoo.
If you get a rash where the rinse runs
A rash in the pattern of the rinse water suggests a reaction to the product.

How It Compares

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Ketoconazole 1% or 2%

Better

Generally the more effective antifungal for both dandruff and seborrheic dermatitis. Pyrithione zinc is cheaper, easier to find in some countries, and milder.

Two Selsun Blue bottles, two Head and Shoulders Clinical Strength bottles and a Vichy Dercos bottle and box16:9 hero for Selenium Sulfide. Never cropped: the tone strip and the corner logo depend on the full frame.

Selenium sulfide

The same

Comparable evidence. Similar results on dandruff and better for tinea versicolor, but it smells, can discolor light or treated hair, and is less pleasant to use.

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

Worse

For dandruff and better for scalp psoriasis. Pyrithione zinc is far easier to live with because it does not stain or smell.

Paula's Choice 2% BHA exfoliant, La Roche-Posay Effaclar cleanser and a CeraVe psoriasis cream pumpLabeled cutaway diagram of a single skin pore, headed Salicylic Acid. The epidermis is a brick-textured band across the top and the dermis is pink below it, with a yellow oil gland at the base of the pore and a small cluster of bacteria inside it. A single dark navy callout line points into the top of the pore: decreases dead cells in pore. There are no other callouts, so the drawing shows one effect where the other ingredient diagrams show two or three.

Salicylic acid

Different job

It lifts scale rather than treating the cause, so it is often used alongside an antifungal rather than instead of one.

Five dark glass tea tree essential oil bottles with glass droppers and one green box on white16:9 hero for Tea Tree Oil. Never cropped: the tone strip and the corner logo depend on the full frame.

Tea tree oil

Worse

A 5% shampoo has some support for mild dandruff, but the effect is smaller and contact allergy is a real risk with regular use.

Myths

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  • "Dandruff means your scalp is dirty." Closer to the opposite. Dandruff is a reaction to a yeast that feeds on scalp oil, and it happens on clean scalps constantly. Washing helps by removing oil and yeast, not dirt.
  • "Dandruff is just a dry scalp." Most dandruff is on oily scalps, and moisturizing a dandruffy scalp makes it worse. Dry scalp flakes are small and white, dandruff flakes larger and greasier, and the treatments differ.
  • "Anti-dandruff shampoo damages or thins your hair." It can leave hair feeling dry, which conditioner solves. No evidence it causes hair loss — untreated seborrheic dermatitis, with its scratching and inflammation, causes more shedding than the shampoo.
  • "You should stop once the flaking is gone." That is when most people relapse. Dandruff is controlled, not cured, and the maintenance dose is once or twice a week.
  • "Switching brands every few weeks stops it becoming resistant." Resistance is not a recognized problem here. When one stops working, it is usually being used less carefully than at first.

Questions Patients Ask

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How long should I leave the shampoo on?

Three to five minutes, worked into the scalp rather than the hair. This is the biggest difference between a shampoo that works and one that does not.

Can I use it every day?

Yes, it is made for regular use with no known problem long term, but most people do not need it daily. Two or three times a week during a flare, once or twice afterward.

Why is it banned in Europe but sold in the United States?

The European Union reclassified the compound in a laboratory hazard category and removed it from cosmetics from March 2022, on toxicity classification rather than reports of harm in people using shampoo. The United States still allows it over the counter. A difference in regulatory approach, not a scientific dispute.

Will it help fungal acne on my chest and back?

Often. Malassezia folliculitis comes from the same yeast, and a body wash left on a few minutes before rinsing is a reasonable first try. Stubborn or widespread cases need an oral antifungal.

Is it safe in pregnancy?

Very little is absorbed from a rinse-off shampoo, but ask the doctor managing your pregnancy, since they know your full picture.

Can I use it on color-treated hair?

Generally yes, and unlike some medicated shampoos it does not usually discolor hair. Frequent washing of any kind fades color, so condition the lengths and keep the shampoo on the scalp.

References

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