How does plaque psoriasis differ from seborrheic dermatitis?
| Feature | Seborrheic dermatitis | Plaque psoriasis |
|---|---|---|
| Scale and edges | Often greasy or yellowish, with more diffuse scaling. | Usually thicker, silvery white scale on clearly defined raised patches called plaques. |
| Common locations | Scalp, eyebrows, folds beside the nose, ears and chest. | Scalp, elbows, knees and lower back; other areas can also be affected. |
| Scalp clues | Diffuse flakes in areas that tend to be oily. | Defined patches that often extend beyond the hairline. |
| Underlying process | The exact cause is unknown; skin yeast and sebum, the skin's oil, play a role. | An immune driven condition involving inflammation and unusually rapid skin cell production. |
| Treatment approach | Antifungal medicines, medicated shampoos and gentle skin care. | Medicines applied to the skin, with light therapy or medicines acting throughout the body for more extensive disease. |
Colour alone is not a reliable dividing line. Psoriasis plaques can look violet or dark on darker skin, and psoriasis in skin folds can be smooth and shiny rather than heavily scaly. Scalp psoriasis can also be the first or only affected area, so clear elbows and knees do not rule it out.2
How do seborrheic dermatitis, psoriasis and eczema differ?
The word dermatitis means skin inflammation, which is a lot of syllables for a broad label. Seborrheic dermatitis and atopic dermatitis are different conditions within that group. Atopic dermatitis, commonly called eczema, tends to cause dry, bumpy, inflamed skin with intense itching. In teenagers and adults, common locations include the hands, inner elbows, neck and around the eyes. Psoriasis more typically produces thick, scaly plaques, although itching can also be severe.236
Is seborrheic dermatitis a form of psoriasis?
No. Seborrheic dermatitis is a separate condition, not another name for psoriasis. Sebopsoriasis describes overlapping features of both, often on the scalp, face, ears or chest. Neither seborrheic dermatitis nor psoriasis is contagious.235
Does the difference change treatment?
Yes. Antifungal treatment can relieve seborrheic dermatitis, but symptoms can return as yeast grows again. A shampoo that helps seborrheic dermatitis can be less effective for scalp psoriasis, so the shampoo aisle is not a diagnostic service. Psoriasis treatments include steroid creams, vitamin D treatments and medicated scalp products. More extensive psoriasis can need light therapy or medicines that act throughout the body. Treatment controls psoriasis rather than curing it.145
How should you care for seborrheic dermatitis?
For teenagers and adults:
- 1Wash your face twice daily. Wet the skin thoroughly, then gently use a fragrance free cleanser or the medicated cleanser your dermatologist recommends.
- 2Rinse thoroughly, then apply a fragrance free moisturizer.
- 3Use your recommended medicated shampoo as often as directed. Follow your treatment plan when a flare starts rather than waiting for it to worsen.
Seborrheic dermatitis is easily irritated. Avoid fragranced products and hot showers, and note whether stress or cold, dry weather precedes flares. Psoriasis also responds to triggers, including stress, infections and skin injury. Avoid scratching or pulling off psoriasis scales, which can cause bleeding and broken skin.57
When should you see a doctor?
Arrange an assessment if the diagnosis is unclear or treatment is not helping. A clinician can examine the patches and sometimes take a small skin sample to distinguish psoriasis from similar conditions. Mention nail pits, crumbling nails, joint pain or swelling; psoriasis can involve the joints, and early treatment can reduce joint damage. Seek medical care for severe pain, swelling and fever, which can signal infection. Before prescription treatment, discuss pregnancy and all medicines or supplements you take, because some psoriasis medicines have serious risks, including birth defects.56
Where this answer comes from
- 1Seborrheic dermatitis: Causesaad.org
- 2Psoriasis: Symptoms, Treatment, Images and Moredermnetnz.org
- 3Dermatitis: Types, Treatments, Causes & Symptomsmy.clevelandclinic.org
- 4Scaly skin diseases. Chronic forms of psoriasisdermnetnz.org
- 5Psoriasis: What It Is, Symptoms, Causes, Types & Treatmentmy.clevelandclinic.org
- 6search.aad.orgsearch.aad.org
- 7Seborrheic dermatitis: Self-careaad.org
