What Causes Dandruff? A Dermatologist Explains How to Tell It from Seborrheic Dermatitis, Psoriasis and Fungal Infection, Why Frequent Washing Isn't the Problem, and How to Treat It
Dandruff (also called pityriasis capitis) is white or yellow flaking from the scalp, caused by skin cells renewing faster than normal. The main cause is a yeast that lives on everyone's skin, Malassezia, which breaks down scalp oil and releases fatty acids that irritate the skin. It is not caused by dirt, and dandruff is the mild end of the same condition as seborrheic dermatitis
Scalp cells normally take about 28 days from formation to shedding as fine, invisible dust. With dandruff, this cycle becomes much shorter, so cells shed in clumps that stay stuck together and show up as flakes on the shoulders. The good news is that most dandruff can be controlled with a medicated shampoo matched to the cause. But flakes on the scalp are not always dandruff. Psoriasis, ringworm of the scalp, allergic reactions to hair dye and a dry scalp can all cause flaking, and each is treated differently. This article separates them one by one, with the names of the active ingredients, their strengths and how long they are actually used
What is dandruff, and how does it really develop?
Dandruff develops from three factors that must occur together
Scalp oil (sebum). The scalp has the densest concentration of oil glands on the body. This is why dandruff begins in the teenage years when oil glands become active, and is uncommon in children before puberty
Malassezia yeast, especially the species M. globosa and M. restricta, which live on everyone's scalp. The yeast breaks down oil and releases free fatty acids such as oleic acid
Individual skin sensitivity. People with a weaker skin barrier react to these fatty acids with mild inflammation and faster cell turnover, while others with the same amount of yeast may have no dandruff at all
This is why antifungal treatment is the core of care. Reducing the yeast means fewer irritating fatty acids, the cell cycle slows back down, and flaking decreases within 2-4 weeks
What causes dandruff: main causes and triggers
Yeast and oil are the root cause, while the factors below are what make dandruff flare up
Cold, dry weather. Dandruff often gets worse from November to January because skin loses moisture easily and people wash their hair less
Washing hair too infrequently. Oil and flakes build up, giving the yeast more to feed on
Stress and lack of sleep clearly trigger flares of seborrheic-type conditions
Hormones. It is more common in men than in women, and symptoms are usually worst between the ages of 20 and 40
Oily hair products, such as hair oil, gel or wax left on the scalp
Certain medical conditions, such as Parkinson's disease and immune deficiency, make seborrheic dermatitis more severe and harder to treat than in other people. If dandruff worsens unusually along with other symptoms, see a doctor
Not a cause: dirt alone. People who wash their hair every day can still have dandruff if their shampoo contains no antifungal ingredient
Types of dandruff, by the look of the flakes
Dandruff and scalp seborrheic dermatitis come in several levels, and each type calls for different treatment. Below are the 4 most common types. Conditions that look like dandruff but are other diseases are covered in the next section
Ordinary dandruff: fine white flakes, no redness
Appearance: small white or gray flakes spread across the scalp and falling onto the shoulders. The scalp under the flakes is not red. Itching is mild to moderate
Cause: Malassezia yeast together with scalp oil. This is the mildest form of the seborrheic group
Severity/urgency: low. You can manage it yourself with a medicated shampoo containing zinc pyrithione, ketoconazole or selenium sulfide. Flaking should decrease within 2-4 weeks
When to see a doctor: you have used a medicated shampoo correctly for a full 4 weeks and the flakes have not decreased, or a red rash begins to appear
Greasy dandruff with yellow scales and a red scalp (scalp seborrheic dermatitis)
Appearance: light yellow, sticky, greasy scales stuck together in patches, with red scalp underneath. It is often worst at the crown, the hairline and behind the ears, and itches more than ordinary dandruff
Cause: the same mechanism as dandruff but with more inflammation, which is why it is called scalp seborrheic dermatitis
Severity/urgency: moderate. It often needs an antifungal shampoo together with a short course of an anti-inflammatory medication
When to see a doctor: the scalp is clearly red, the itching keeps you awake, there is weeping, or a medicated shampoo alone has not been enough after 4 weeks. For details on this condition, read Seborrheic dermatitis: causes, symptoms and how to tell it apart from other conditions
Dandruff that spreads to the face, eyebrows, sides of the nose and behind the ears
Appearance: flaking and red rash on the eyebrows, the creases beside the nose, the front hairline, behind the ears, inside the ear or in the middle of the chest, together with dandruff on the scalp
Cause: these areas have many oil glands, just like the scalp, so the same yeast can cause a rash there
Severity/urgency: moderate. Facial skin is thinner than the scalp, so do not use strong steroid creams or use them for long on your own
When to see a doctor: the facial rash has not improved within 2 weeks, or you cannot tell whether it is seborrheic dermatitis, an allergic rash or an autoimmune disease. A red rash on both cheeks in a butterfly shape is not dandruff and needs to be examined by a doctor
Cradle cap in babies
Appearance: thick, yellow, greasy scales stuck firmly on the scalp of babies aged 2 weeks to 3 months. Most are not itchy, and the baby is not fussy
Cause: the baby's oil glands are still affected by hormones from the mother, together with yeast on the skin
Severity/urgency: low. It usually clears on its own within 6-12 months. Apply vegetable oil or petroleum jelly to soften the scales for 15-30 minutes, then wash with baby shampoo and gently lift the scales off with a soft brush. Do not pick or scrape them off hard
When to see a doctor: the rash spreads to the skin folds or buttocks and is very itchy (it may be atopic dermatitis), there is weeping, or the baby has a fever. Do not use adult medicated shampoo on babies without consulting a doctor
5 conditions mistaken for dandruff but treated differently
If you have used anti-dandruff shampoo for a long time without improvement, the most common reason is that it was never dandruff in the first place. The five conditions below can also cause flaking on the scalp
Scalp psoriasis
Appearance: thick, silvery-white scales with sharply defined, raised edges, often extending past the hairline onto the forehead, behind the ears or the nape of the neck. Scratching may cause small pinpoint bleeding
Cause: an immune-mediated disease that makes skin cells divide much faster than normal. It is not caused by fungus, so ordinary anti-dandruff shampoo helps very little
Severity/urgency: moderate to high. It is a chronic disease that needs anti-inflammatory topical medication, and some people need oral or injectable medication
When to see a doctor: you also have scaly patches on the elbows, knees or lower back, pitted or crumbling nails, or joint pain. Read more at Psoriasis: causes and early symptoms and Psoriasis creams: what are the options?
Ringworm of the scalp (tinea capitis)
Appearance: round patches of hair loss with gray scales, with broken hairs visible as black dots. Some people develop a soft, swollen, pus-filled lump (kerion), and the lymph nodes at the back of the neck may be enlarged
Cause: dermatophyte fungi, which are a different organism from the yeast that causes dandruff. It spreads from household members, pets, combs or hats and is common in children
Severity/urgency: higher than dandruff. It needs oral antifungal medication such as griseofulvin or terbinafine for 4-8 weeks, and medicated shampoo alone will not cure it. If treated late, permanent scarring hair loss can result
When to see a doctor: a child has patchy hair loss with scaling, and should see a doctor promptly. The doctor will scrape the scales and examine them for fungus before prescribing medication. Read more at Scalp ringworm: symptoms, causes and treatment
Contact allergy to hair dye or shampoo
Appearance: intense itching, burning, a red scalp, flaking or weeping, most obvious at the hairline, behind the ears and on the nape. It usually starts 1-3 days after dyeing hair or changing products
Cause: allergy to para-phenylenediamine (PPD) in dark hair dye, to fragrance, or to preservatives in shampoo
Severity/urgency: moderate. If the face and eyelids swell as well, treat it as urgent. Stopping the allergen matters more than changing shampoo
When to see a doctor: the rash returns every time you dye your hair, the face swells, or you do not know what you are allergic to. A doctor may perform a patch test. Read more at Contact dermatitis and patch testing
Dry scalp
Appearance: fine, powdery white flakes that are not greasy or red, with dry hair and dry skin elsewhere. It is worst in cold weather or after washing with very hot water
Cause: the scalp loses too much water and oil, the opposite of dandruff, where there is too much oil
Severity/urgency: low. Using a strong anti-dandruff shampoo every day can make dryness worse, so use a gentle shampoo and lower the water temperature
When to see a doctor: flaking has not decreased after 2-3 weeks of changing how you wash, or there is a red rash. Read more at Dry, flaking scalp: what causes it?
Head lice (pediculosis capitis)
Appearance: intense scalp itching, especially at the nape and behind the ears, with white specks stuck firmly to the base of hairs that people often mistake for dandruff
Cause: lice and their eggs, spread by head-to-head contact, hats or combs
Severity/urgency: moderate. The easiest way to tell the difference is that dandruff blows or brushes off, while nits stick tightly to the hair and have to be slid off with a fine-toothed nit comb
When to see a doctor: lice come back after a full course of treatment, or scratching has caused an infected sore. Read more at Head lice: causes and how to recognize nits
Quick comparison
Ordinary dandruff → dry white flakes, no redness, only on the scalp, improves with medicated shampoo within 2-4 weeks
Seborrheic dermatitis → greasy yellow scales, red scalp, spreads to the sides of the nose, eyebrows and behind the ears
Psoriasis → thick silvery-white scales with sharp borders, extends past the hairline, with rash on the elbows or knees
Scalp ringworm → patchy hair loss, broken hairs, seen in children, needs oral medication
Contact dermatitis → intense itching, starts after dyeing hair or changing products, at the hairline and behind the ears
Dry scalp → fine powdery flakes, not greasy, worse with frequent washing using harsh shampoo
How is dandruff different from a fungal infection?
This question causes a lot of confusion, because dandruff does involve a fungus, but a different kind from the "fungal infection" most people mean
Dandruff involves Malassezia yeast, a normal resident of everyone's skin. It is not contagious, does not cause patchy hair loss, and does not have to be eliminated completely, only reduced
Scalp ringworm is caused by dermatophytes, which are contagious, make hairs break and fall out in patches, and need weeks of oral antifungal medication
If there are flakes together with circular hair loss, especially in a child, always think of ringworm before dandruff
How does a doctor diagnose dandruff?
Most dandruff can be diagnosed by looking, but when the signs do not fit, a dermatologist will do further checks as follows
Examine rashes elsewhere on the body, such as the elbows, knees, nails, eyebrows and sides of the nose, to tell psoriasis from seborrheic dermatitis
Magnified scalp examination (dermoscopy). Psoriasis shows evenly arranged red dots, while seborrheic dermatitis shows branching blood vessels and yellow scales
Scraping flakes for examination with KOH solution when ringworm is suspected. It takes only a few minutes
Fungal culture when the type of fungus must be confirmed before a long course of oral medication
Patch testing when an allergy to hair dye or a shampoo ingredient is suspected
Scalp biopsy. This is rarely used, only when the rash does not respond to treatment and another disease is suspected
Medicated anti-dandruff shampoo: choosing the right active ingredient
Each anti-dandruff shampoo has different active ingredients. Read the ingredient name on the back label, not the product name. Below are the ingredients with medical evidence behind them, with the strengths and directions doctors usually recommend
Ketoconazole 2%. The antifungal with the most evidence for dandruff and seborrheic dermatitis. Use twice a week for 2-4 weeks, then reduce to once a week or once every 1-2 weeks to prevent relapse. Suitable for greasy dandruff and seborrheic dermatitis
Ciclopirox 1%. Antifungal and anti-inflammatory. Use 2-3 times a week for 4 weeks. An option when there has been no response to ketoconazole
Selenium sulfide 1-2.5%. Reduces yeast and slows cell turnover. Use twice a week for 2 weeks, then reduce to once a week. It may change the color of treated hair and has an odor, so rinse thoroughly
Zinc pyrithione 1-2%. A mild antifungal. Can be used at every wash or 2-3 times a week. Suitable for ordinary dandruff and long-term use
Piroctone olamine 0.5-1%. Antifungal and gentle. Can be used often, and suits use as a daily shampoo while keeping symptoms under control
Salicylic acid 2-3%. Helps dissolve thick scales. It does not kill fungus, so use it together with an antifungal ingredient. Suitable for firmly attached scales or psoriasis
Coal tar 0.5-5%. Slows cell division. Used in psoriasis and seborrheic dermatitis that does not respond to other treatment. It has a strong smell, may stain light or white hair yellow, and makes the skin sensitive to sunlight
A simple map of where to start
Plain white flakes, mild itching → zinc pyrithione or piroctone olamine
Greasy, yellow flakes, red scalp → ketoconazole 2% or ciclopirox 1%
Thick, firmly attached scales → salicylic acid to lift them first, then an antifungal shampoo, and have a doctor rule out psoriasis
No improvement after a full 4 weeks with one ingredient → switch to a different class of ingredient, or see a doctor
How to use medicated shampoo so it works
The active ingredient has to stay in contact with the scalp long enough to work. Most people who say anti-dandruff shampoo did not work rinsed it off too quickly
Wet the hair thoroughly with warm water, not very hot water
Use about one teaspoon of medicated shampoo and work it into a lather on the scalp, not on the ends of the hair
Leave it on for 3-5 minutes. You can wash your face or bathe in the meantime. If you have a rash on the eyebrows or beside the nose, you can dab the lather there for 1-2 minutes and then rinse it off
Rinse thoroughly, then use conditioner on the ends only if your hair is dry
On days you don't use the medicated shampoo, use a gentle shampoo as usual
If used correctly, itching usually decreases within 1 week and flaking decreases clearly within 2-4 weeks. This is how you know it is working
Medication doctors use when shampoo alone is not enough
For heavily inflamed seborrheic dermatitis, or dandruff that does not respond to medicated shampoo, a doctor may add the following
Clobetasol propionate 0.05% steroid shampoo. Apply to a dry scalp, leave for 15 minutes, then rinse off. Use twice a week for no more than 4 weeks, alternating with antifungal shampoo
Betamethasone valerate 0.1% scalp lotion. Once a day for 1-2 weeks during a flare, then stop or reduce
Facial rash. Use hydrocortisone 1% once or twice a day for no more than 7 days, or ketoconazole 2% cream once or twice a day for 2-4 weeks. If it keeps coming back, the doctor may use a non-steroid anti-inflammatory medication such as tacrolimus 0.1% or pimecrolimus 1% twice a day
Oral itraconazole. Used in widespread seborrheic dermatitis that has not responded to topical medication, for example 200 mg a day for 7 days. A doctor must first assess liver disease and any other medicines you take, because this drug interacts with many others
The choice of medication, its strength and how long to use it are decisions for a doctor who has examined the actual rash. You should not buy steroid medication for the scalp and use it continuously on your own, because when you stop, symptoms often return stronger, and prolonged use on the face can thin the skin and cause a rash around the mouth
How to wash your hair to prevent dandruff
Wash regularly. People with oily hair should wash every day or every other day. Washing less often lets oil and flakes build up
Use warm water, not hot. Very hot water dries the scalp and increases itching
Massage with your fingertips and do not scratch with your nails. Scratching causes abrasions and inflammation
Keep using medicated shampoo once a week to maintain control, even after the flakes are gone, because the yeast can build back up within a few weeks
Dry your hair before bed. Damp hair left for the whole night irritates the scalp
Reduce hair oil, gel and wax that touches the scalp directly
What can I do about a very itchy scalp from dandruff?
The itching comes from the inflammation that the yeast triggers, so treating the cause works better than scratching
Start with ketoconazole 2% shampoo twice a week, leaving it on for 3-5 minutes each time
On days you don't use the medicated shampoo, use a shampoo with zinc pyrithione or piroctone olamine
Keep your nails short, and replace scratching with pressing or gentle patting
If the itching keeps you from sleeping, the scalp is red, or there is weeping, see a doctor, because you may need a short course of anti-inflammatory medication, or it may not be dandruff
To read about other causes of an itchy head, see Itchy scalp: what causes it?
What should I do if my scalp is peeling in sheets?
Thick sheet-like peeling is not typical of ordinary dandruff. It is usually heavily inflamed seborrheic dermatitis or psoriasis
Do not pick or pull off the scales, because it causes bleeding and pulls hair out with them
Soften the scales first with a shampoo or lotion containing 2-3% salicylic acid, or with oil applied and left on for 30-60 minutes before washing
Follow with an antifungal shampoo twice a week
See a doctor if the scales are thick, sharply bordered or extend past the hairline, or if you have a rash elsewhere, so that psoriasis, which needs different medication, can be ruled out
How are hair loss and dandruff related?
Dandruff itself does not cause permanent hair loss, but there are 3 indirect links
Hard scratching and inflammation make hairs break and fall out more, temporarily
Scalp inflammation can make hair that is already thinning from genetics look thinner faster, and dandruff is often found together with genetic hair thinning
Conditions that look like dandruff, such as scalp ringworm and severe psoriasis, do cause real hair loss
If you lose more than 100 hairs a day for more than 2 months, or the thinning is in a pattern or in patches, the cause should be investigated separately. Read more at Hair loss: causes and the 5 types and Anti-hair-loss shampoo: does it really help?
Why doesn't anti-dandruff shampoo work for me?
Rinsing it off too quickly. If you don't leave it on for 3-5 minutes, the active ingredient doesn't have time to work
Not using it long enough. You should judge the result at 4 weeks, not after 3-4 washes
Stopping as soon as the flakes are gone. The yeast builds back up, so symptoms return within a few weeks. You need a maintenance phase
It isn't dandruff. It may be psoriasis, ringworm, an allergic rash or a dry scalp
Using a harsh shampoo every day until the scalp is dry, which leads to even more flakes
Warning signs: when to see a dermatologist
You have used medicated shampoo correctly for a full 4 weeks and are not better
The scalp is very red, with weeping, pus or pain
Patchy hair loss, or broken hairs, especially in a child
Thick scales with sharp borders, extending past the hairline, or a rash on the elbows, knees or nails
The rash spreads to the face, chest or back
Dandruff worsens quickly along with weight loss, fever, or a condition that suppresses the immune system
Common myths about dandruff
"Dandruff is caused by being unclean." Not true. The main cause is yeast and oil. People who wash their hair every day can have it too
"Washing often makes dandruff worse." Not true for people with oily hair. Regular washing with a suitable shampoo reduces flaking. The problem is using a harsh shampoo or hot water until the scalp is dry
"Dandruff is contagious." Not true. Malassezia yeast lives on everyone's skin, but scalp ringworm is contagious, so the two must be told apart
"Coconut oil will cure dandruff." Oil can help soften scales, but it is food for the yeast. If left on the scalp without being washed out, it can make dandruff worse
"One anti-dandruff wash is enough." You need to use it continuously for at least 2-4 weeks, and then keep control going
Key takeaways
Dandruff is caused by Malassezia yeast together with scalp oil, which shortens the normal cell cycle of about 28 days. It is not caused by dirt
Ordinary dandruff is white flaking without redness, while seborrheic dermatitis is greasy yellow scales on a red scalp and can spread to the face
Psoriasis, scalp ringworm, allergic rash from hair dye, dry scalp and head lice can look like dandruff but are treated differently
The medicated shampoo with good evidence is ketoconazole 2%, twice a week, left on for 3-5 minutes, for 2-4 weeks, then continued to keep control
Judge the result at 4 weeks. If you are not better, change the active ingredient or see a doctor
Patchy hair loss, thick sharply bordered scales or pus on the scalp are reasons to see a dermatologist
Frequently asked questions about dandruff
How is dandruff different from a fungal infection?
Dandruff involves Malassezia yeast, which lives on everyone's scalp and is not contagious. The signs are white or yellow flakes without patchy hair loss, and it is treated with antifungal shampoo. Fungal infection of the scalp, or ringworm (tinea capitis), is caused by dermatophytes, which are contagious, make hairs break and fall out in circles, are common in children and need oral antifungal medication such as griseofulvin or terbinafine for 4-8 weeks. Shampoo alone is not enough. If there are flakes together with patchy hair loss, a doctor should scrape the scales and test for fungus before starting medication
What can I do about a very itchy scalp from dandruff?
Start with ketoconazole 2% shampoo twice a week, working it over the whole scalp and leaving it on for 3-5 minutes before rinsing. On other days use a shampoo with zinc pyrithione or piroctone olamine. Use warm water instead of hot, and massage with your fingertips instead of scratching with your nails. Itching usually decreases within 1 week. If the itching keeps you from sleeping, the scalp is red or there is weeping, see a dermatologist, because you may need a short course of anti-inflammatory medication, or the cause may be another condition such as an allergic rash from hair dye or head lice
What should I do if my scalp is peeling in sheets?
A scalp that peels in thick sheets is usually heavily inflamed seborrheic dermatitis or psoriasis, not ordinary dandruff. Do not pick or pull the scales, because it causes bleeding and pulls hair out. First soften the scales with a product containing 2-3% salicylic acid, or with oil left on for 30-60 minutes, then wash it out, followed by an antifungal shampoo twice a week. If the scales have sharp borders, extend past the hairline, or you also have a rash on the elbows, knees or nails, see a doctor to rule out psoriasis, which needs a different anti-inflammatory medication from dandruff
How are hair loss and dandruff related?
Dandruff does not cause permanent hair loss, but hard scratching makes hairs break and fall out more for a while, and scalp inflammation makes hair that is thinning from genetics look thinner faster. Once dandruff is under control, hair lost for this reason usually returns to normal within 2-3 months. But if there is patchy hair loss, broken hairs or clear thinning in a pattern, think of other conditions such as scalp ringworm, psoriasis or hormonal hair thinning, and see a dermatologist to find the cause, because the treatments are very different
How should I wash my hair to prevent dandruff?
People with oily hair should wash every day or every other day. Use warm water instead of hot, and work the shampoo into the scalp with your fingertips, not your nails. If you use a medicated shampoo, leave it on for 3-5 minutes before rinsing. Once the dandruff has cleared, keep using an antifungal medicated shampoo once a week to prevent it from coming back, because the yeast can build back up within a few weeks. Dry your hair before bed and reduce hair oil, gel or wax that touches the scalp. People with a dry scalp should use a gentle shampoo and avoid strong anti-dandruff shampoo every day
How is dandruff treated, and why does it come back?
Dandruff is a chronic condition that can be controlled but can return, because Malassezia yeast is a normal skin resident that can never be eliminated completely. Treatment therefore has two phases. First, use a medicated shampoo such as ketoconazole 2% twice a week for 2-4 weeks until the flakes clear. Second, maintain control with the medicated shampoo once a week or once every 1-2 weeks, which greatly reduces how often it comes back. If you have done this fully and it still keeps returning, or the flakes are thick and red, see a doctor to check whether it is seborrheic dermatitis, psoriasis or another condition
Read more skin condition articles at All skin condition articles
Written by Dr. Patara Voravutinon, Dermatologist · Last reviewed October 20, 2026
The information in this article is general knowledge and not a diagnosis or personalized prescription. The choice of medication, its strength and how long to use it must be assessed by a doctor. Results vary from person to person, and every medication can have side effects.
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