How to get rid of dandruff: what works and how to use it

Dandruff is not a sign of poor hygiene, and it is usually not just a dry scalp. It is a common, harmless condition linked to a yeast that lives on almost every scalp, and it can be controlled with the right shampoo.

Quick answer: Use an anti-dandruff shampoo with an active such as ketoconazole, zinc pyrithione, selenium sulfide or piroctone olamine. Lather it into the scalp, leave it on for about 5 minutes (follow the label), and rinse well. Use it once or twice a week. If one active stops working, try a different one. See a doctor if there is no change after about 4 weeks.

What causes dandruff?

Dandruff is a mild form of seborrheic dermatitis, a common skin condition that affects oily areas such as the scalp. A yeast called Malassezia lives on nearly everyone's scalp. It feeds on scalp oil and releases fatty acids that can irritate the skin in some people. Irritated skin renews itself faster, and the extra cells fall off as visible flakes.

Things that can make flaking worse include:

• an oily scalp;
• stress and poor sleep;
• cold, dry winter weather (many people improve in summer);
• washing too rarely, which lets oil and flakes build up;
• a family history of seborrheic dermatitis or psoriasis;
• some medical conditions and medicines that affect the immune system or nerves.

Dandruff is not contagious, and you cannot catch it from a brush, a pillow or another person.

Dandruff or dry scalp?

The two look alike, but the fix is different. Anti-dandruff shampoos work on the yeast and oil problem. They will not help much if your scalp is simply dry.

If you are not sure which one you have, start with an anti-dandruff shampoo for 2–4 weeks. If your scalp feels tighter and drier, switch to a gentle shampoo and read about itchy, sensitive scalp. If your scalp gets oily within a day, see oily scalp and hair.

Which anti-dandruff ingredients work?

The anti-dandruff family includes several active ingredients. Most work by reducing the yeast or by loosening flakes. These are the ones named by dermatology bodies:

• Ketoconazole: an antifungal that targets the yeast. Many people find it the strongest option. In the US, a lower-strength shampoo is sold without a prescription, and stronger versions need one.
• Zinc pyrithione: an antifungal and antibacterial ingredient that is gentle enough for regular use.
• Selenium sulfide: slows how fast skin cells are shed and reduces the yeast. It has a strong smell and can discolor lightened, gray or dyed hair if it is not rinsed out well.
• Piroctone olamine: a milder antifungal that is common in shampoos sold in Europe.
• Salicylic acid: a beta hydroxy acid that loosens thick, stuck-on flakes. It works best with an antifungal active, and it can dry the hair.
• Sulfur: an older ingredient that helps loosen flakes and reduce the yeast.
• Coal tar: slows skin-cell turnover. It has a strong smell, can stain light hair and can make skin more sensitive to sun, so cover your scalp outdoors.

Prescription options exist too. Doctors may prescribe stronger antifungal shampoos, or short courses of a steroid lotion or foam for a red, very itchy scalp. A dermatologist decides which one fits, because long steroid use can thin the skin.

You can browse medicated shampoos and scalp care on Glowpedia. Check the active ingredient on the label, not just the front of the bottle.

How to use an anti-dandruff shampoo

1. Wet your hair and apply a small amount of shampoo to the scalp, not the lengths.
2. Massage with your fingertips (not your nails) for a minute to loosen flakes.
3. Leave the lather on for about 5 minutes. Some labels say up to 10, so follow the one on your bottle. This contact time is what lets the active work.
4. Rinse very well.
5. Use conditioner on the lengths and ends only, especially after ketoconazole or salicylic acid, which can leave hair dry.

Straight, fine or oily hair

The American Academy of Dermatology says people with fine, straight or oily hair can wash often, even daily, and use the dandruff shampoo about twice a week. Use a regular shampoo on the other days.

Curly and coily hair

Curly and coily hair is drier and more fragile, so it is washed less often. Dermatologists suggest using the dandruff shampoo about once a week if your scalp tolerates it, and applying it only to the scalp. Follow with your usual conditioner. If your wash day is every two weeks, try using it on wash day and gently cleansing the scalp in between. Your routine for coily hair can stay much the same.

What if my dandruff shampoo stops working?

Sometimes a shampoo seems to work for a few months and then flakes return. The simple fix is to rotate: use a shampoo with a different active, or alternate two actives (for example zinc pyrithione one week and ketoconazole the next). You may also need to give a product a full 2–4 weeks before deciding it has failed.

Also check the basics. Rinse well, leave the lather on long enough, and use the shampoo on the scalp rather than only on the hair.

Habits that can make dandruff worse

• Scratching with nails or a comb. This can break the skin and lead to infection or sore patches.
• Heavy oils and thick styling products on the scalp. Malassezia depends on fats, so heavy oils may make flaking worse in some people. If you oil your hair, try keeping oil on the lengths during a flare.
• Fragrance and essential oils. These can irritate a sensitive scalp or cause allergic reactions in some people. Patch test a new product, and people with sensitive scalps may prefer fragrance-free ones. Some shampoos contain tea tree oil, which has been used for dandruff, but it is a common cause of allergic reactions.
• Skipping washes during a flare. Oil and flakes build up and the yeast has more to feed on.
• Rough scrubbing and very hot water. Both can leave the scalp more irritated, which can make itching worse.

How long does it take to work?

Itching and flaking often start to improve within the first couple of weeks, and the NHS advises trying a medicated shampoo for up to 4 weeks before deciding whether it helps. Dermatology sources describe dandruff as a long-term condition that tends to come and go. After flakes clear, many people stay on the shampoo about once a week, or every second week, to keep them away. If you stop completely, flakes often return.

When to see a dermatologist

Flakes are not always dandruff. See a doctor or dermatologist if:

• there is no improvement after about 4 weeks of medicated shampoo;
• your scalp is red, swollen, sore, oozing or crusted;
• the flaking is thick, silvery and sharply edged (this can be scalp psoriasis);
• you have flaky, itchy patches on your face, ears or body;
• you notice hair loss, round scaly patches or broken hairs (a fungal scalp infection is possible, especially in children);
• the itching is severe or keeps you awake.

If you are pregnant or breastfeeding, ask your doctor before using a prescription treatment. Ask about thinning hair too, as hair thinning and shedding has many causes and needs a proper check.

FAQ

Does washing my hair more often help dandruff?

For many people with an oily scalp, yes, because washing removes the oil the yeast feeds on. If you have curly or coily hair, you may use the medicated shampoo only about once a week.

Is dandruff caused by dirty hair?

No. Dandruff is not caused by poor hygiene, though flakes can be more visible if you wash infrequently.

Will dandruff go away on its own?

It can improve in warm weather or when stress eases, but it often returns. Most people need a shampoo routine to keep it under control.

Can I use an anti-dandruff shampoo on dyed hair?

Yes, but some actives, especially selenium sulfide and coal tar, can discolor lightened or gray hair. Apply to the scalp, rinse well, and check the label.

Can stress cause dandruff?

Stress does not cause the yeast, but it is known to make flares more likely in people who already have seborrheic dermatitis.

Sources

• How to treat dandruff (American Academy of Dermatology)
• Dandruff (NHS)
• Seborrhoeic dermatitis (DermNet)
• Seborrheic dermatitis: symptoms, causes and treatment (Cleveland Clinic)