What Causes Dandruff?

Dandruff is caused by a fungus called Malassezia that lives on everyone's scalp. In people who are susceptible, it triggers an accelerated skin cell turnover — the resulting dead skin flakes off as the white or yellowish flakes visible on hair and clothing. It is extremely common and not contagious or caused by poor hygiene.

The Most Effective Treatments

  1. 1

    Use a medicated anti-dandruff shampoo

    These are the first-line treatment and work for most people. Key active ingredients: Zinc pyrithione (Head and Shoulders, Pantene Anti-Dandruff) — antifungal, available everywhere. Selenium sulphide (Selsun Blue) — effective for more stubborn dandruff. Ketoconazole (Nizoral) — the strongest option, available at pharmacies, best for persistent dandruff. Coal tar (T/Gel) — slows skin cell turnover, effective but has a distinctive smell.

  2. 2

    Leave the shampoo on for 3–5 minutes

    Most people rinse anti-dandruff shampoo off immediately like regular shampoo — this significantly reduces effectiveness. Apply to wet scalp, massage in gently, and leave for 3–5 minutes before rinsing. The active ingredient needs contact time to work.

  3. 3

    Use 2–3 times per week initially

    Use the medicated shampoo every other wash until dandruff clears (usually 2–4 weeks). Then reduce to once or twice a week for maintenance. You can alternate with your regular shampoo on other wash days.

  4. 4

    Rotate between shampoos if one stops working

    Some people find their dandruff shampoo becomes less effective over time. Switching between formulas with different active ingredients every few months prevents this. Try zinc pyrithione for 2 months, then switch to selenium sulphide.

Supporting Habits

  • Shampoo regularly — infrequent washing allows oil and dead skin to accumulate, worsening dandruff
  • Manage stress — stress is a known trigger for dandruff flare-ups
  • Avoid harsh hair products — some styling products and dry shampoos irritate the scalp
  • Limit hot showers — very hot water strips scalp oils and can worsen the condition
If OTC shampoos are not workingSee a GP or dermatologist. Severe dandruff may actually be seborrhoeic dermatitis — a more inflammatory condition that responds to prescription topical steroids or stronger antifungal treatments. Psoriasis of the scalp can also look like dandruff and requires different treatment.

Frequently Asked Questions

Some research suggests diet plays a role. High sugar and refined carbohydrate intake may worsen dandruff in some people by feeding the Malassezia fungus. Zinc deficiency has been linked to dandruff. A balanced diet rich in zinc (meat, nuts, seeds, legumes), omega-3s and B vitamins supports scalp health. Diet alone is rarely sufficient treatment but can complement medicated shampoo.
Tea tree oil has antifungal properties and some studies show modest effectiveness against dandruff. It is not as effective as medicated shampoos with zinc pyrithione or ketoconazole. Some people find adding a few drops to their regular shampoo helpful as a complementary approach. Always dilute before applying to the scalp — undiluted tea tree oil causes irritation.