Seborrheic Dermatitis
Seborrheic Dermatitis — a common, chronic inflammatory condition that causes flaky, scaly patches and redness in areas rich in oil glands, such as the scalp, sides of the nose, eyebrows, and ears. On the scalp it often appears as dandruff, while on the face it can look like greasy, yellowish scaling. It tends to come and go in flares and is thought to involve the skin’s response to a naturally occurring yeast.
Key points
- It affects sebum-rich zones and is linked to an inflammatory reaction to Malassezia yeast that normally lives on the skin.
- Symptoms often include flaking, redness, itching, and greasy scales, ranging from mild dandruff to more noticeable patches.
- Flares can be influenced by stress, cold or dry weather, hormones, and certain health conditions.
- Management commonly includes gentle cleansing and products with ingredients like zinc pyrithione, ketoconazole, or salicylic acid, guided by a professional when needed.
Look-alikes, and what separates them
| Mistaken for | The distinguishing feature |
|---|---|
| Scalp psoriasis | Thicker, sharply bordered silvery plaques crossing the hairline |
| Rosacea | Flushing, papules and visible vessels, with no scale |
| Contact dermatitis | Follows the outline of whatever touched it |
| Atopic eczema | Flexural, intensely itchy, with dry rather than greasy scale |
| Perioral dermatitis | Papules ringing the mouth, with spared skin at the lip border |
| Simple dry scalp | Fine white flakes without redness, easing with a moisturiser |
Yeast, sebum and an inflammatory response
Malassezia is a normal resident of human skin. It cannot make its own fatty acids, so it splits sebum triglycerides with its enzymes, leaving free fatty acids such as oleic acid behind. In some people the skin mounts an inflammatory response to those by-products, and that response is the condition. This is neither an infection nor a hygiene problem: the yeast lives on everyone, and the difference is how a person reacts.
It also explains the map. Lesions sit where sebaceous glands are dense — scalp, eyebrows, nasolabial folds, behind the ears, the central chest. The scale is greasy and yellowish because it carries sebum, unlike the dry silvery scale of psoriasis. The course relapses and remits, worse in cold months. Dandruff is the mild end of the same spectrum.
Keeping it under control
The useful actives reduce the yeast population or the inflammation it provokes: ketoconazole, zinc pyrithione, selenium sulfide and ciclopirox. On the scalp they work best two or three times weekly, with a few minutes of contact before rinsing, and the effect is judged at 2–4 weeks. Salicylic acid or urea lifts adherent scale; on the face a non-foaming cleanser is enough.
Be realistic about the result. This is controlled rather than cured, and stopping usually brings it back within weeks, so most people settle on a maintenance frequency. Rotating between actives is often suggested; the evidence is modest. Mild topical anti-inflammatories are prescribed for stubborn flares, but strength, site and duration are clinician decisions.
When persistent flaking should be assessed
Cradle cap, and any rash on a baby, belongs with a clinician rather than a shampoo bought for an adult. For adults, book an appointment if 4–6 weeks of an appropriate antifungal brings no improvement, if the eyelid margins are involved, if patches weep or crust, or if the rash spreads beyond oil-rich sites.
Two associations make stubborn disease worth a proper look rather than indefinite self-treatment. Extensive, treatment-resistant seborrhoeic dermatitis is more common where immunity is suppressed, including in untreated HIV infection, and it occurs more often in Parkinson’s disease and related conditions. Neither is cause for alarm, but both are reasons to have a case that will not settle seen.
Frequently asked
Is seborrheic dermatitis caused by poor hygiene?
No; it stems from inflammation and the skin’s reaction to natural yeast and oil, not from being unclean, and over-washing can sometimes worsen irritation.
Is dandruff the same as seborrheic dermatitis?
Dandruff is considered a mild form of seborrheic dermatitis on the scalp, while the broader condition can also involve redness and scaling on the face and other oily areas.
Will it come back if I stop treating it?
Usually, within a few weeks. Treatment lowers the yeast population and the inflammation, but neither the yeast nor the tendency to react to it goes away, so maintenance suits it better than stopping.
Why does it flare in winter?
Cold dry air, indoor heating and less daylight coincide, and ultraviolet light appears to suppress Malassezia somewhat. Many notice the reverse in summer, though sweating can offset it.
Is cradle cap the same condition?
It is described as the infant form and usually settles on its own within months. Anything on a baby’s skin should still be shown to a clinician rather than treated with an adult product.
Can I use an antifungal shampoo on my face?
Some are used that way, but facial skin is thinner and closer to the eyes. Check with a pharmacist or clinician first.
Related topics
This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.
