ConditionSkin, hair & nails
Dandruff: Causes and Treatment That Works
Dandruff is a common, harmless, long-term scalp condition in which the skin sheds excess flakes, usually with mild itch. It is the mildest form of seborrheic dermatitis and is driven by an inflammatory reaction to Malassezia, a yeast that lives on everyone's scalp. It affects up to half of adults at some point. Dandruff cannot be cured permanently, but medicated shampoos containing ketoconazole, zinc pyrithione, selenium sulfide, salicylic acid or coal tar control it well when used regularly.
Also called: Pityriasis capitis, pityriasis simplex capitis, mild seborrheic dermatitis of the scalp
At a glance
- What it is
- Chronic, non-inflammatory to mildly inflammatory scalp flaking; the mildest end of seborrheic dermatitis.
- Cause
- Skin sensitivity to Malassezia yeast and its byproducts, plus oil production.
- Who gets it
- Mostly teens and adults up to middle age; more common in men.
- Treatment
- Anti-dandruff shampoo 2 to 3 times a week, then once a week to maintain.
- Outlook
- Comes and goes for years but is well controlled; not contagious and does not damage hair.
When to get help
See a doctor within a day or two
- A child with scaly bald patches or broken hairs (possible scalp ringworm)
- A scalp that becomes very red, swollen, painful, oozing or crusted, or a fever
Book a routine appointment
- No improvement after 4 to 6 weeks of regular medicated shampoo
- Thick plaques, scaling beyond the hairline, or nail changes that suggest psoriasis
- Red, scaly patches on the face, ears and chest as well as the scalp
- Hair loss in the affected area
Usually safe to manage at home
- Typical mild flakes and itch that respond to over-the-counter shampoo
What causes dandruff
Three factors combine:
- Malassezia yeast: these yeasts live on oily skin in everyone. They break down scalp oil (sebum) into fatty acids, including oleic acid.
- Individual sensitivity: in people prone to dandruff, those fatty acids irritate the scalp, triggering mild inflammation and faster skin cell turnover. Cells clump together and shed as visible flakes.
- Sebum: more oil means more food for the yeast, which is why dandruff starts after puberty and is uncommon in children.
Flares are linked to cold, dry weather, stress, illness, infrequent washing and some neurological conditions such as Parkinson's disease. People with weakened immune systems, including HIV, often have more severe seborrheic dermatitis.
Dandruff is not caused by poor hygiene or by a dry scalp, and it is not an allergy. If your flakes may be something else, the dandruff symptom guide compares the look-alikes.
Symptoms
- white or yellowish flakes on the scalp, hair and shoulders
- mild itching
- a slightly oily scalp, sometimes with faint pink areas
- flakes that worsen in winter and improve in summer
When redness and greasy scale spread to the eyebrows, sides of the nose, behind the ears, beard area or chest, the diagnosis is seborrheic dermatitis rather than simple dandruff.
Diagnosis
A doctor diagnoses dandruff by looking at the scalp. Tests are needed only to rule out other conditions: a skin scraping for fungus (ringworm) or, rarely, a biopsy if psoriasis or another scalp disease is suspected.
Dandruff treatment: which shampoo to use
| Active ingredient | How it works | Notes |
|---|---|---|
| Ketoconazole 1% (OTC) or 2% (Rx) | Antifungal, reduces Malassezia | Among the most effective; use 2 to 3 times a week |
| Zinc pyrithione | Antifungal and antibacterial | Gentle, widely available, good for frequent use |
| Selenium sulfide | Slows cell turnover, antifungal | Can discolor light or chemically treated hair; rinse well |
| Ciclopirox (Rx) | Antifungal, anti-inflammatory | Alternative to ketoconazole |
| Salicylic acid | Loosens and removes scale | Helps thick flakes; can dry the scalp |
| Coal tar | Slows skin cell growth | Useful for psoriasis overlap; strong smell, can stain light hair |
| Tea tree oil (5%) | Mild antifungal | Some evidence; can irritate or cause allergy |
How to use medicated shampoo properly
- Massage it into the scalp, not just the hair.
- Leave it on for 3 to 5 minutes before rinsing.
- Use it 2 to 3 times a week for at least 4 weeks. You can use your normal shampoo on other days.
- When flakes are controlled, drop to once a week or every other week to maintain.
- If one ingredient stops working, rotate with another.
- Follow the label directions. Stop if the scalp burns or becomes very irritated.
Prescription treatments
If over-the-counter shampoos fail after 4 to 6 weeks, a doctor may prescribe:
- 2% ketoconazole shampoo or ciclopirox shampoo
- A short course of a mild steroid scalp solution, foam or shampoo for itch and redness
- Calcineurin inhibitor creams for affected facial skin
- Very rarely, an oral antifungal for severe, resistant seborrheic dermatitis
Tips for different hair types
- Tightly curled or coily hair that is washed less often: dermatologists suggest a weekly anti-dandruff shampoo, applied mainly to the scalp, and avoiding heavy oils directly on the scalp, which can feed yeast.
- Color-treated hair: zinc pyrithione and ketoconazole are less likely to discolor than selenium sulfide or coal tar.
- Oily hair: more frequent washing helps keep sebum down.
Dandruff in babies: cradle cap
Greasy yellow crusts on an infant's scalp are cradle cap, the infant form of seborrheic dermatitis. It usually clears by 6 to 12 months. Gently massage in baby oil or a mild emollient, then wash with baby shampoo and lift scales with a soft brush. Do not use adult anti-dandruff shampoos on babies without medical advice.
Outlook
Dandruff tends to come and go over years and often improves after middle age. It is cosmetic and uncomfortable but does not harm health or cause permanent hair loss. Regular maintenance with medicated shampoo keeps most people flake-free.
Frequently asked questions
What is the best shampoo for dandruff?
Ketoconazole and zinc pyrithione shampoos are among the most effective for most people. Selenium sulfide, salicylic acid and coal tar are good alternatives. The key is leaving the shampoo on for a few minutes and using it 2 to 3 times a week.
Can dandruff be cured permanently?
No. Dandruff is a long-term tendency because the yeast involved always lives on the scalp. It can be controlled very well, and many people stay clear with a weekly medicated wash. It often becomes milder with age.
How long does dandruff treatment take to work?
Most people see fewer flakes within 2 to 4 weeks of using a medicated shampoo 2 to 3 times a week. If there is no improvement after 4 to 6 weeks, try another active ingredient or see a doctor about prescription options.
Is dandruff a fungal infection?
Not exactly. Malassezia yeast is present on everyone's scalp. Dandruff is an inflammatory reaction to the yeast in susceptible people, not an infection you catch. That is why antifungal shampoos help but the problem returns when they are stopped.
Does oiling the hair help dandruff?
Heavy oils applied to the scalp can make dandruff worse because Malassezia feeds on certain oils. Light oils on the hair shaft are fine. For a genuinely dry scalp, a light, non-greasy moisturizer is a better choice.
Sources
This guide was written from current patient and clinical guidance, including:
- American Academy of Dermatology: How to treat dandruff
- American Academy of Dermatology: Seborrheic dermatitis - Diagnosis and treatment
- NHS: Dandruff
- MedlinePlus: Dandruff
- DermNet: Seborrhoeic dermatitis