Seborrhoeic dermatitis of the scalp: more than dandruff

If your flakes come with redness, greasy yellowish scale or patches beside your nose and eyebrows, you may have seborrhoeic dermatitis rather than simple dandruff. It is common, not contagious and can be controlled, even if it tends to come back ¹.

Dandruff or seborrhoeic dermatitis?

The two are closely related. A review describes them as a continuous spectrum of the same condition ²:

• Dandruff stays on the scalp and causes itchy flaking without visible inflammation
• Seborrhoeic dermatitis causes flaking or scaling with inflammation, and can affect other oily areas of the body

The American Academy of Dermatology (AAD) describes dandruff as possibly the mildest form of seborrhoeic dermatitis. Both cause white to yellowish scale that may be dry or greasy and itchy ¹. See dandruff treatment.

Signs to look for

On the scalp, seborrhoeic dermatitis may show as ill-defined scaly patches or diffuse scale ³. Beyond the scalp, it can appear on ^{1 3}:

• The eyebrows, beard and hairline
• The ears and the skin behind them
• The sides of the nose
• The eyelid margins (scaly, red eyelids)
• The chest, especially in men

Skin tone matters. On darker skin, the rash often looks pink, slightly purple or lighter than the surrounding skin, rather than red ¹. DermNet notes it can appear as scaly, lighter patches, sometimes petal-shaped, around the hairline and forehead ³.

Who gets it?

DermNet estimates it affects 3% to 12% of people ³. It is more common in men than women ^{1 3}, and there are two peaks: in babies (where it is called cradle cap) and in adolescents and adults ³.

Some factors are linked with more severe or stubborn disease ^{3 1}:

• Oily skin
• A family history of seborrhoeic dermatitis or psoriasis
• A weakened immune system, including HIV infection
• Certain neurological conditions, such as Parkinson's disease
• Lack of sleep and stressful events

What causes it?

The cause is not fully understood ³. The main suspect is *Malassezia*, a yeast that lives normally on the skin. It breaks down oils in sebum, and this may trigger inflammation in people who are susceptible ³. A 2019 treatment review describes the condition as an inflammatory response to *Malassezia* in oily areas ⁴. Research on the scalp microbiome has also linked seborrhoeic dermatitis with higher levels of *Malassezia* and some bacteria compared with healthy scalps ⁵.

What makes it flare?

• Stress is a common trigger ^{1 3}
• Season: in temperate countries, flares are more common in winter, and it may improve in warm, humid weather ¹

Malaysia does not have a winter, but many people notice flares during stressful periods, after poor sleep, or when they wash less often.

Treatment

There is no cure for seborrhoeic dermatitis, but treatment can ease the itch and reduce, and sometimes clear, the rash ¹. Treatment aims to clear the signs, relieve itch and keep it under control over the long term ⁴.

Medicated shampoos

DermNet lists shampoos containing ketoconazole, ciclopirox, selenium sulfide, zinc pyrithione, coal tar or salicylic acid, used twice weekly for at least a month, and continued if necessary ³. Note that some strains of *Malassezia* resist azole antifungals such as ketoconazole, so switching to zinc pyrithione or selenium sulfide may help ³.

Prescription treatments

A doctor may add ³:

• Short courses of a mild steroid lotion to calm a flare, usually for 1 to 3 weeks
• Calcineurin inhibitors (such as tacrolimus) as steroid-sparing options
• Keratolytics such as salicylic acid to lift thick scale
• For stubborn cases in adults, oral antifungals, certain antibiotics or light therapy

Avoid using strong steroid creams for long periods without advice. Overuse can thin the skin ³.

Herbal and natural remedies

Tea tree oil shampoo and aloe vera have been reported as alternative options ^{3 4}. However, DermNet says the effectiveness of many herbal remedies is uncertain ³.

Why early treatment matters

The AAD advises treating seborrhoeic dermatitis early. Without treatment, scale can thicken, and scratching can lead to infection. On darker skin, it can also leave dark spots and patches, especially on the face ¹.

Does it cause hair loss?

Seborrhoeic dermatitis is not a typical cause of significant hair loss, but heavy scaling and scratching can make hair look thinner and damage hair shafts. If you are losing a lot of hair, see sudden severe hair fall and get it checked.

Living with it

• Keep a regular washing routine with a medicated shampoo. See how often to wash your hair
• Avoid scratching. See itchy scalp
• Note your triggers, such as stress and lack of sleep
• Expect it to come and go. In adults it is often long-term and may need maintenance treatment ³

When to see a doctor

See a doctor if over-the-counter shampoos have not helped after about a month, if the rash is spreading to your face or body, or if it is sore, weepy or infected. Other conditions such as psoriasis, scalp ringworm and eczema can look similar ³. See scalp psoriasis.

The bottom line

Seborrhoeic dermatitis is a common, long-term condition linked to the skin's natural yeast and oil. It cannot be cured, but medicated shampoos and short courses of prescription treatment can keep it well controlled.

Frequently asked questions

Is seborrhoeic dermatitis the same as dandruff?

They are related. Dandruff is the mildest form, without visible inflammation; seborrhoeic dermatitis adds redness and can affect other areas ^{2 1}.

Is it contagious?

No. Seborrhoeic dermatitis is not contagious ¹.

Can seborrhoeic dermatitis be cured?

There is no cure, but treatment can relieve itch and reduce or clear the rash ¹.

How often should I use a medicated shampoo?

DermNet suggests twice weekly for at least a month, and longer if needed ³.

Educational content. Not medical advice.