Seborrhoeic dermatitis

Also called Dandruff, Cradle cap, Seborrhoeic eczema

Dandruff and its more inflamed relatives, driven by a yeast everybody has. Controllable, not curable, and it always comes back when treatment stops.

What it is

A common inflammatory skin condition affecting areas rich in oil glands: the scalp, eyebrows, sides of the nose, ears, chest and skin folds.

It is a reaction to Malassezia, a yeast that lives on everybody's skin, in people whose skin responds to it. That is why antifungal shampoos work, and why the condition returns when they stop: the yeast is not being eradicated, only kept down.

Dandruff is its mildest form. Cradle cap is the infant version, harmless, and almost always gone by a year.

Two associations are worth knowing. It is much more common and more severe in Parkinson's disease and after stroke, for reasons related to sebum production and facial movement. And severe, sudden or treatment-resistant seborrhoeic dermatitis in an adult can be a presenting sign of HIV, which is worth knowing rather than worrying about.

It is not caused by poor hygiene, it is not contagious, and washing more does not fix it.

Signs you might notice

Flaking, scaling and dandruff on the scalp, sometimes with yellowish greasy scale.

Redness and scaling on the sides of the nose, eyebrows, behind the ears and in the beard area. On brown and black skin it often appears as lighter or darker patches rather than redness, and the pigment change can be more distressing than the rash.

Itching, sometimes considerable.

In babies: thick yellow greasy crusts on the scalp, sometimes the eyebrows and nappy area, without the baby being bothered by it.

See a GP for: severe or widespread disease; anything not responding to over-the-counter treatment; signs of infection with weeping, crusting and pain; or eyelid involvement causing sore, crusted lid margins.

How it can affect day-to-day life

Visible flaking on dark clothing and a red face are what people actually mind, and the condition is often dismissed as trivial by clinicians while genuinely affecting confidence at work.

The chronic pattern is the hard part: it improves with treatment, people stop, it returns, and they conclude the treatment failed. Framing it as ongoing maintenance, like brushing teeth, changes adherence completely.

It flares with stress, cold dry weather, illness and tiredness.

Never pick or scrub cradle cap off; it lifts damaged skin with it.

For someone with Parkinson's or after a stroke who cannot easily wash their own hair or face, this becomes a personal care task that needs to be someone's job.

Supporting someone well

Use an antifungal shampoo containing ketoconazole, selenium sulphide or zinc pyrithione, leaving it on for several minutes before rinsing. The contact time matters more than the frequency.

Keep using it, at a reduced frequency, once it has settled. Maintenance is the whole strategy.

For the face, a mild antifungal cream, with a short course of a weak steroid for flares only.

For cradle cap, soften with an emollient or olive oil, then gently brush with a soft brush and wash off. Do not pick.

Ask about the eyelids if the lid margins are sore and crusted; that needs specific care.

Ask for a HIV test if the disease is severe, sudden or resistant in an adult. It is a routine question, not an accusation.

Include hair and face washing in the care plan for anybody who cannot manage it themselves.

Where to get help

A pharmacist for shampoos and mild creams.

A GP practice for severe or resistant disease, eyelid involvement, or if infection is suspected.

British Association of Dermatologists publish patient leaflets on seborrhoeic dermatitis and cradle cap.