Anti-dandruff shampoo ingredients compared: ketoconazole, zinc pyrithione, selenium and more

Walk down the shampoo aisle of any pharmacy in Malaysia and you will see a long row of anti-dandruff products. Some list ketoconazole, others zinc pyrithione, selenium sulfide, salicylic acid, coal tar, ciclopirox or piroctone olamine. The labels often look similar, and it is not obvious which one to pick or why one product works for a friend but not for you.

This guide explains what each common anti-dandruff ingredient does, the evidence behind it, common side effects, who each one may suit and how to use medicated shampoo so it actually has a chance to work. It is general information, not personal medical advice. If flaking, itch or redness persists, or you notice hair loss, see a doctor or pharmacist.

Short answer

• Dandruff and seborrhoeic dermatitis are linked to Malassezia yeast, natural skin oil and individual sensitivity, so many anti-dandruff ingredients are antifungal ¹².
• Ketoconazole, zinc pyrithione, selenium sulfide and ciclopirox mainly target the yeast ³⁴.
• Salicylic acid and coal tar help loosen and reduce scale rather than mainly targeting yeast ⁵.
• How you use the shampoo matters as much as which one you choose. Apply it to the scalp and leave it on for about five minutes before rinsing ³.
• If one product stops helping, switching or alternating active ingredients is a common approach ³.
• Persistent or severe symptoms need a diagnosis, because psoriasis, contact dermatitis and fungal infection can look similar ⁶.

Why dandruff happens

Dandruff is the mild end of a spectrum that includes seborrhoeic dermatitis. It is thought to involve three things together: oil from the scalp's sebaceous glands, Malassezia yeasts that live on normal skin, and how sensitive a person's skin is to the substances those yeasts produce ¹. The result is faster shedding of skin cells, visible flakes and, often, itch.

This is why antifungal shampoos are the backbone of treatment. They reduce the amount of yeast on the scalp, which can calm the reaction. It also explains why dandruff tends to come back after treatment stops: the yeast and the oil are part of normal skin, so most people need ongoing maintenance. For more background, see dandruff treatment and seborrhoeic dermatitis.

The main ingredients compared

Ketoconazole

Ketoconazole is an azole antifungal. Shampoos usually contain 1% (often available without prescription) or 2% (in some countries prescription-only or pharmacy-only) ⁷. It is one of the most studied options for dandruff and seborrhoeic dermatitis ⁴.

• How it is used: often two or three times a week at first, then less often for maintenance.
• Possible side effects: scalp irritation, dryness, a change in hair texture and, rarely, an allergic reaction ⁷.
• Hair loss note: some small studies suggest ketoconazole shampoo may help as an add-on in pattern hair loss, but the evidence is limited and of low quality ⁸. See ketoconazole shampoo and hair loss.

Zinc pyrithione

Zinc pyrithione has antifungal and antibacterial activity and is found in many everyday anti-dandruff shampoos. It is generally gentle enough for frequent use and suits many people with mild dandruff ³.

• Good for: mild, recurring flakes; people who want a shampoo they can use often.
• Possible side effects: usually mild; irritation is uncommon.

Selenium sulfide

Selenium sulfide slows the turnover of skin cells and has antifungal effects ⁴.

• Good for: moderate dandruff; some people who did not respond to zinc pyrithione.
• Possible side effects: a distinctive smell, oily hair and, in some people, discolouration of light, grey or chemically treated hair. Rinse thoroughly ³.

Ciclopirox and piroctone olamine

Ciclopirox is an antifungal used in some medicated shampoos for seborrhoeic dermatitis ⁴. Piroctone olamine is a related antifungal found in some cosmetic anti-dandruff shampoos. Both may be options when azole products do not suit you.

Salicylic acid

Salicylic acid is a keratolytic, which means it softens and loosens scale so it washes away more easily ⁵. It is useful for thick flakes but does not mainly target yeast, so it is often paired with an antifungal.

• Possible side effects: dryness and stinging, especially on broken or sensitive skin.

Coal tar

Coal tar slows the growth of skin cells and reduces scale. It is used for dandruff, seborrhoeic dermatitis and scalp psoriasis ⁵⁹.

• Possible side effects: a strong smell, staining of light hair and fabrics, irritation and increased sensitivity to sunlight.
• Tip: follow the label carefully and ask a pharmacist whether it suits you.

Tea tree oil and other botanicals

Tea tree oil shampoos are popular. There is limited evidence for some benefit in mild dandruff, but tea tree oil can cause irritation and allergic contact dermatitis in some people ¹⁰. Natural does not automatically mean gentle.

Comparison table

How to use anti-dandruff shampoo properly

Many people say "anti-dandruff shampoo did not work" when the real problem was how it was used.

1. Wet the hair and apply the shampoo to the scalp, not just the lengths.
2. Massage gently with fingertips, not nails.
3. Leave it on for about five minutes, or as directed on the label ³.
4. Rinse thoroughly, especially behind the ears and at the nape.
5. Use conditioner on the lengths if the medicated shampoo feels drying.
6. Repeat two or three times a week at first, then reduce to a maintenance routine once flakes settle.

If you have very thick flakes, a salicylic acid or coal tar product first, followed by an antifungal, may help the antifungal reach the skin. Ask a pharmacist how to combine them.

Choosing where to start

A reasonable approach for mild dandruff is:

• Start with zinc pyrithione or ketoconazole 1%, used properly for three to four weeks.
• If there is little change, switch to a different active ingredient, such as selenium sulfide or ketoconazole 2% if available.
• For thick scale, add salicylic acid or coal tar.
• Once controlled, use a medicated shampoo about once a week and your usual shampoo on other days.

If flakes are thick, red or sharply outlined, or extend to the hairline, ears or face, see a doctor. Seborrhoeic dermatitis and scalp psoriasis may need prescription treatment such as a steroid or antifungal lotion ⁶⁹. See scalp psoriasis.

Special situations

Coloured or chemically treated hair

Selenium sulfide and coal tar are more likely to affect colour. Zinc pyrithione or ketoconazole may be easier choices. Rinse well and avoid using medicated shampoo straight after a colour service.

Dry or sensitive scalp

Medicated shampoos can feel drying. Using a gentle shampoo on non-treatment days and conditioner on the lengths often helps. If the scalp burns or stings, stop and see sensitive, burning scalp.

Children, pregnancy and breastfeeding

Ask a doctor or pharmacist before using medicated shampoos for young children or during pregnancy or breastfeeding. Scaly patches with hair loss in children can be tinea capitis, which needs oral treatment ¹¹. See scalp ringworm.

Covering hair in a hot climate

Long hours under a tudung, cap or helmet keep the scalp warm and damp. Wash often enough, dry the roots before covering and see how often to wash your hair.

Reading the label

• Check the active ingredient and its percentage, not just the brand name.
• Look for clear contact time instructions.
• Be cautious with hair-growth claims on dandruff products.
• Fragrance-heavy products may irritate sensitive skin.

A sample maintenance routine

This is an example only. Adjust it with your pharmacist or doctor.

• Weeks one to four: a medicated shampoo two or three times a week, left on for about five minutes; a gentle shampoo on other wash days.
• If flakes are thick: a salicylic acid shampoo first on treatment days, followed by the antifungal.
• Once settled: a medicated shampoo about once a week, increasing again at the first sign of flakes returning.
• If it seems to stop working: rotate to a product with a different active ingredient for a few weeks.
• Throughout: keep oils and heavy styling products off the scalp, and dry the roots before covering your hair.

Flare-ups are common during hot, humid months, stress or illness, so it helps to keep a medicated shampoo at home rather than waiting until the scalp is very itchy.

Common myths

• "Dandruff means a dirty scalp." Dandruff is linked to yeast, oil and skin sensitivity, not poor hygiene alone.
• "Dandruff means a dry scalp, so oil it." Heavy oils can feed the yeast and make some cases worse. See dry scalp vs dandruff.
• "If one anti-dandruff shampoo fails, none will work." Switching active ingredients often helps.
• "Medicated shampoo damages hair if used often." Used as directed, most are suitable for regular use; conditioner helps dryness.
• "Once the flakes stop, the problem is gone." Dandruff often returns without maintenance.

Common mistakes

• Rinsing the shampoo off straight away.
• Applying it only to the hair, not the scalp.
• Giving up after one or two washes.
• Stopping completely once flakes improve.
• Using many products at once, which makes it hard to tell what helps or irritates.
• Treating psoriasis, ringworm or contact dermatitis as dandruff for months.

Questions to ask a pharmacist or doctor

• Is this dandruff, seborrhoeic dermatitis, psoriasis or something else?
• Which active ingredient should I try first, and for how long?
• How should I combine a scale-loosening product with an antifungal?
• Is this product safe for coloured hair, for my child or during pregnancy?
• When should I come back if it does not improve?

The bottom line

Most anti-dandruff shampoos work by reducing Malassezia yeast or loosening scale. Ketoconazole, zinc pyrithione, selenium sulfide and ciclopirox are antifungal; salicylic acid and coal tar mainly reduce scale. The best choice depends on your scalp, hair and how you respond, and correct use — on the scalp, about five minutes' contact, regular maintenance — matters as much as the ingredient. If symptoms persist, are severe or come with hair loss, see a doctor. For related topics, see dandruff treatment and scalp detox.

Frequently asked questions

Which anti-dandruff ingredient is best?

There is no single best one for everyone. Ketoconazole, zinc pyrithione and selenium sulfide all target the yeast linked to dandruff. Many people try one for a few weeks and switch if it does not help.

How long should I leave anti-dandruff shampoo on?

Usually around five minutes, or as the label says, so the active ingredient has time to work before rinsing.

How often should I use medicated shampoo?

Often two or three times a week at first, then once a week or so to keep flakes under control, alongside your normal shampoo on other days.

Can I alternate different anti-dandruff shampoos?

Yes. Some people find rotating two products with different active ingredients helps when one alone stops working as well.

Does ketoconazole shampoo help hair loss?

Some small studies suggest it may support treatment of pattern hair loss, but evidence is limited and it is not a substitute for proven treatments.

Does selenium sulfide affect hair colour?

It can discolour light, grey or chemically treated hair in some people, so rinse well and follow the label.

Is coal tar shampoo safe?

It is used for dandruff and psoriasis, but it has a strong smell, can stain light hair and may make the scalp more sensitive to sunlight. Follow the label and ask a pharmacist.

When should I see a doctor?

See a doctor if flakes and itch do not improve after several weeks of medicated shampoo, or if you have thick plaques, redness, oozing, pain or hair loss.

Educational content. Not medical advice.