What it is
Seborrheic dermatitis is a common, long-lasting but usually mild skin condition that causes flaking, redness and sometimes greasy-looking scales. It tends to appear in areas with many oil glands, such as the scalp, sides of the nose, eyebrows, eyelid edges, behind the ears, the center of the chest and sometimes skin folds. It is not contagious and it is not caused by poor hygiene.
The exact cause is not fully understood. It is generally thought to involve an inflammatory reaction to Malassezia, a yeast that lives on most people’s skin, together with individual factors such as oil production and the skin barrier. It can come and go over the years, and many people find it flares in colder, drier months.
Dandruff is generally considered a milder form that affects the scalp only; the article on dandruff flakes covers that area in more detail. In babies, a related form on the scalp is often called cradle cap, which typically settles on its own.
What it looks like
Appearance depends on the area and on skin tone.
- Scalp: Flaky scales that may be white or yellowish, sometimes with itching and redness.
- Face: Red or pink patches (which may look darker, brown, purple or lighter than surrounding skin on deeper skin tones) with fine, sometimes greasy-looking flakes, especially alongside the nose, in the eyebrows and between the brows.
- Eyelids: Flaking and redness along the lash line.
- Chest and body: Round or ring-like patches with flaking.
Itching ranges from none to bothersome. Because the condition can look like eczema, psoriasis, rosacea or a contact reaction, the diagnosis is not always obvious. Redness around the nose and cheeks can also be mistaken for rosacea redness, and in some people the two coexist.
Possible triggers and contributors
Triggers vary between people, and in many cases no clear cause is found. Commonly mentioned factors include:
- Cold, dry weather and low humidity
- Stress and tiredness
- Illness
- Hormonal changes
- Certain neurological conditions and weakened immune systems, which are associated with more severe disease
- Harsh products that irritate the skin, or infrequent washing of oily areas
The role of diet is unclear. There is no widely accepted food that causes or clears the condition, so be cautious about claims of dramatic results from a particular diet or supplement.
General care ideas
Care often aims to calm inflammation and keep flaking under control, since the condition tends to return. The following are general, low-risk habits. They are not a treatment plan.
- Wash affected areas regularly with a gentle cleanser. Letting oil and flakes build up can make things look and feel worse. Washing too aggressively, with hot water or scrubs, can irritate the skin and cause stripped skin, so keep it moderate.
- Keep moisturizing, since dryness and irritation can aggravate flaking. Light, fragrance-free options are often more comfortable on the face. Richer and lighter textures work differently because humectants emollients and occlusives each do a different job.
- Be gentle with flakes. Picking or scraping scales off can cause soreness, bleeding and infection.
- Avoid harsh exfoliants and strong actives on affected skin. These can irritate it further, and the damage to a compromised skin barrier can extend a flare.
- Use sun protection, choosing a gentle sunscreen. Sunscreen under makeup can be arranged to avoid heavy layering over flaky areas.
- Mind your hair and scalp products. Some people alternate shampoos, and certain medicated shampoos are widely sold for the scalp. Follow the instructions on the label, and ask a pharmacist if you are unsure which suits you. Avoid applying scalp products to the face or eyelids unless they are labeled for that use.
- Be careful around the eyes. Eyelid involvement is best discussed with a clinician rather than self-treated.
When to see a professional
A doctor or dermatologist can confirm the diagnosis and suggest suitable treatments, which often include medicated shampoos or creams used for short periods and then as needed to prevent recurrence. The right choice depends on the area, severity and your health history. Seek an appointment if:
- Symptoms persist despite a few weeks of gentle care
- Itching or discomfort is significant
- Skin is very red, swollen, weeping, painful or crusting, which can mean infection or another condition
- The eyelids are affected or your eyes feel irritated
- It is spreading widely or came on suddenly with other symptoms
- You are unsure it is seborrheic dermatitis
- A baby has a thick, inflamed or spreading rash
Seborrheic dermatitis is generally controllable, but not usually curable. Many people have periods when it is clear and periods of recurrence, and results vary with each person and treatment. Expect some trial and adjustment, and be wary of any product that claims a permanent fix.