Seborrhoeic dermatitis is a common, long-running inflammatory condition affecting areas where sebaceous glands are densest: the scalp, the sides of the nose, the eyebrows and the chest. A yeast that lives normally on everybody's skin is involved, which is why it is treated as an inflammatory response rather than as an infection.
What is actually happening in the skin?
Look at where seborrhoeic dermatitis appears and the mechanism starts to explain itself. The scalp, the eyebrows, the creases either side of the nose, behind the ears, the centre of the chest: these are the places where sebaceous glands are packed most densely. Dermatitis simply means inflammation of the skin, and the seborrhoeic part records that this one follows the oil.
A yeast of the Malassezia group lives on the skin of essentially everybody, and it does well in oily environments. In some people the skin mounts an inflammatory response to its presence or to the products of its metabolism, and that response is what you see. The organism is not an invader. It is a permanent resident, and the condition reflects the reaction to it rather than the fact of it.
This is why calling the dermatitis an infection misleads. Nothing is being caught, nothing is being passed on, and eliminating the yeast entirely is neither possible nor the goal.
Several things shift the balance. Cold weather worsens it for many people, stress and tiredness are widely reported as aggravating it, and it can be more troublesome and more extensive in people whose immune system is affected by other conditions. That last association is one reason a clinician may ask questions that seem to have nothing to do with your scalp.
How would a dermatologist describe it?
Scale is the term for the flakes, and clinicians describe its character: in seborrhoeic dermatitis the scale is often greasy and yellowish rather than dry and white, which helps distinguish this dermatitis from other scaling conditions.
Erythema again means redness, and in this dermatitis it tends to be described alongside a specific distribution rather than on its own. That distribution does most of the diagnostic work. A clinician will speak of the nasolabial folds, the creases running from the nose to the corners of the mouth, of the retroauricular area behind the ears, and of the presternal chest.
Blepharitis describes inflammation along the eyelid margins, which occurs in some people as part of the same picture. Cradle cap is the familiar name for the infantile form, which behaves quite differently from the adult condition and generally settles by itself.
Where the dermatitis overlaps with psoriasis on the scalp, you may hear the deliberately hedged term sebopsoriasis. That is not vagueness for its own sake; the two conditions genuinely can be hard to separate on the scalp, and saying so is more honest than choosing arbitrarily.
What usually happens at a consultation?
Expect the history to cover how long this has gone on, whether it comes and goes, whether it worsens in particular seasons, what you use on your hair and skin, and whether your eyelids are involved. Questions about your general health and any other medical conditions are routine here and are not idle curiosity.
The examination looks at all the classic sites, not only the one you mention. Somebody who comes about their scalp will usually have their face, ears and chest looked at too, because the pattern across those areas is the strongest single piece of evidence.
A clinician may also look for features suggesting a different condition, since scalp scaling has several possible explanations and the distinctions matter for what follows.
What is worth asking?
Ask which sites the clinician can see involvement at, including any you had not noticed. People frequently discover that their eyebrows or the creases beside their nose have been quietly involved for years, and knowing the full extent changes how you judge whether things are settling.
Ask whether your eyelids should be looked at. Eyelid involvement is easy to overlook from both sides of the consultation and it can be the part that causes the most day-to-day irritation.
Enquire about what typically happens over time in a case like yours. This is a fluctuating condition, and understanding that recurrence is expected prevents a great deal of unnecessary discouragement when it returns.
Where hair products or washing habits come up, get specific advice about yours rather than general principles. What suits one scalp irritates another, and a clinician can be concrete about this in a way that no page can.
What this page does not do
It does not tell you whether the scaling on your scalp or face is seborrhoeic dermatitis. Several conditions resemble this dermatitis closely, and separating them requires an examination. No treatment, shampoo or product is recommended here, and no schedule is given.
Common questions
Is dandruff the same as seborrhoeic dermatitis?
They sit on the same spectrum. Dandruff is generally used for scaling of the scalp without much inflammation, while seborrhoeic dermatitis describes the same process with visible redness and irritation, on the scalp or elsewhere. Clinicians treat them as related rather than separate.
Is seborrhoeic dermatitis contagious?
No. The yeast involved lives on everyone's skin as a normal resident, so there is nothing to catch. What differs between people is how their skin responds to it, which is why one person develops the condition and another never does.
Why does it keep coming back after it clears?
It is generally described as a long-term condition that fluctuates rather than one that resolves permanently. The underlying tendency remains even when the skin looks settled, and many people notice a seasonal rhythm to it. Recurrence is expected rather than a sign anything went wrong.
Why does it affect the sides of my nose and my eyebrows?
Those areas carry a high density of sebaceous glands, and the condition follows that distribution closely. The scalp, the eyebrows, the creases beside the nose, behind the ears and the centre of the chest are the classically described sites for exactly that reason.
Is it caused by poor hygiene?
No, and the assumption causes a fair amount of unnecessary embarrassment. The condition reflects how an individual's skin responds to a normal resident organism, not how often they wash. Over-washing tends to irritate the affected areas rather than help them.
Sources
- Seborrhoeic dermatitis — patient information leaflet — British Association of Dermatologists (United Kingdom) · accessed
- Dandruff — conditions — NHS (United Kingdom) · accessed
Last updated . How this page was written.