Definition and epidemiology
Seborrheic dermatitis is a common, chronic papulosquamous skin disorder characterized by erythematous patches with greasy, yellow-white scale distributed over sebaceous gland-rich areas: scalp, eyebrows, nasolabial folds, ears, and presternal chest.
It has a bimodal age distribution:
- Infants (cradle cap): typically appears in the first 3 months of life and usually resolves spontaneously by 6-12 months.
- Adults: peak prevalence in the 30s to 60s, with a slight male predominance.
Overall prevalence in the general adult population is approximately 1-5%. Prevalence rises sharply in certain populations, notably HIV-infected patients (up to 30-80% depending on CD4 count and disease stage) and patients with Parkinson disease and other neurologic conditions affecting sebum regulation or hygiene. It is more common and often more severe in cold, dry seasons and improves with sun exposure in many patients.
- Seborrheic dermatitis is associated with Malassezia yeast overgrowth and abnormal host inflammatory response, not a primary infection
- Severe or sudden-onset seborrheic dermatitis in an adult should prompt HIV testing
- Classic distribution: scalp, eyebrows, nasolabial folds, ears, presternal chest
- Infantile cradle cap is self-limited, typically resolving by 6-12 months
- First-line treatment is topical antifungal (ketoconazole) plus short-term low-potency topical corticosteroid for flares
- Strongly associated with Parkinson disease and other neurologic conditions
- Sebopsoriasis describes clinical overlap between seborrheic dermatitis and psoriasis
- Maintenance antifungal therapy is needed long-term since the condition is chronic and relapses after stopping treatment
Etiology and risk factors
The exact cause is multifactorial, involving sebaceous gland activity, Malassezia yeast colonization, and individual immune/inflammatory response.
Key contributing factors
- Malassezia species (M. furfur, M. globosa, M. restricta): lipophilic yeasts that are normal skin flora but trigger an abnormal inflammatory and irritant response in susceptible individuals
- Sebum production: disease activity correlates with sebaceous gland activity, explaining distribution and timing (infancy, puberty, adulthood)
- Immunosuppression: HIV/AIDS is strongly associated with severe, widespread, treatment-resistant disease
- Neurologic and psychiatric disease: Parkinson disease, stroke, spinal cord injury, depression (likely related to reduced facial movement/hygiene and autonomic dysfunction)
- Other associations: zinc deficiency, niacin deficiency, drugs (lithium, psoralen, interferon), cold weather, stress, and genetic predisposition
It is not caused by poor hygiene, though hygiene can affect severity.
Pathophysiology
Seborrheic dermatitis results from an interplay between sebaceous secretions, the skin's lipid composition, Malassezia metabolism, and host immune response.
Malassezia yeasts metabolize sebum lipids, producing free fatty acids (including oleic acid) that are irritating to the skin and disrupt the epidermal barrier. This triggers a non-specific inflammatory response and keratinocyte hyperproliferation, leading to the characteristic scaling.
In immunocompetent hosts, the response is thought to reflect individual susceptibility and skin barrier dysfunction rather than yeast quantity alone, since fungal counts do not always correlate with disease severity. In immunosuppressed patients (notably HIV), impaired cutaneous immune surveillance allows more severe, extensive, and treatment-refractory disease, suggesting an important immune-mediated component rather than purely a yeast-overgrowth phenomenon.
Clinical features
Presentation varies by age and distribution but shares a common morphology: erythematous patches with greasy, yellowish or white scale, often with mild pruritus.
Distribution
- Scalp (dandruff, pityriasis sicca, to thick adherent scale)
- Eyebrows and glabella
- Nasolabial folds and alae nasi
- Retroauricular and external ear canal
- Presternal and interscapular chest
- Intertriginous areas (axillae, groin) in severe cases
Infantile form (cradle cap)
- Thick, greasy yellow scale on the scalp, typically painless and not pruritic
- May extend to face, neck folds, and diaper area
- Self-limited, usually resolves by 6-12 months
Adult form
- Chronic, relapsing course with flares (often winter) and remissions (often summer)
- Pruritus is common, especially on the scalp
- Can mimic or coexist with psoriasis ("sebopsoriasis") when thick, well-demarcated plaques occur
Diagnosis
Diagnosis is clinical, based on characteristic morphology and distribution. No specific laboratory test is required in typical cases.
- History: chronicity, relapsing-remitting course, seasonal variation, pruritus
- Examination: erythematous, greasy, scaling patches in sebaceous areas
- Skin biopsy: rarely needed; reserved for atypical or refractory cases to exclude psoriasis or cutaneous lymphoma. Histology shows superficial perivascular lymphocytic infiltrate, mild spongiosis, and characteristic parakeratosis around follicular ostia ("shoulder parakeratosis")
- HIV testing: should be considered in adults with sudden-onset, severe, extensive, or treatment-resistant seborrheic dermatitis, especially if other risk factors are present
No routine fungal culture or KOH prep is needed; Malassezia is normal flora and a positive finding does not confirm diagnosis.
Differential diagnosis
| Condition | Distinguishing feature |
|---|---|
| Psoriasis | Thicker, well-demarcated silvery plaques; nail pitting, extensor surfaces; may overlap (sebopsoriasis) |
| Atopic dermatitis | Personal/family history of atopy, flexural distribution, intense pruritus |
| Tinea capitis/corporis | Positive KOH/fungal culture, may show hair loss or annular lesions |
| Contact dermatitis | Clear exposure history, distribution matches contactant |
| Rosacea | Papules/pustules, telangiectasia, flushing, lacks greasy scale |
| Pityriasis versicolor | Hypo/hyperpigmented macules on trunk, different distribution |
| Lupus erythematosus (discoid/SLE) | Photosensitivity, scarring, positive ANA/immunologic markers |
| Langerhans cell histiocytosis (infants) | Petechiae, systemic signs, biopsy required if cradle cap is atypical or refractory |
Management
Treatment is suppressive, not curative, aiming to control inflammation and scaling since the condition is chronic and relapsing.
Scalp disease
- First-line: antifungal shampoos (ketoconazole, ciclopirox, or selenium sulfide) used regularly, often continued intermittently for maintenance
- Zinc pyrithione or tar-based shampoos are alternatives
- Short courses of topical corticosteroid solutions/lotions for flares with significant inflammation or pruritus
Face and body
- Topical antifungals: ketoconazole or ciclopirox cream, applied to affected areas
- Topical corticosteroids (low potency, e.g., hydrocortisone): short-term use for flares due to risk of skin atrophy and rebound with prolonged facial use
- Topical calcineurin inhibitors (tacrolimus, pimecrolimus): useful steroid-sparing option for facial or long-term maintenance therapy
Infantile form
- Usually self-limited; gentle emollients and regular washing with mild shampoo suffice
- Mineral oil or white petrolatum can soften thick scale before gentle brushing
- Topical antifungal or low-potency steroid reserved for persistent or inflamed cases
Severe/refractory disease
- Consider underlying immunosuppression (HIV testing)
- Oral antifungals (itraconazole) may be used in extensive or resistant adult disease per specialist guidance
- Maintenance therapy (intermittent antifungal use) is generally recommended by major dermatology guidelines to prevent relapse, since relapse is expected on stopping treatment
Complications and prognosis
Seborrheic dermatitis is a benign, chronic condition without systemic complications in most patients, but it can significantly affect quality of life due to visible scaling and pruritus.
- Secondary bacterial or candidal infection: can occur in excoriated or intertriginous areas
- Psychosocial impact: cosmetic concern from flaking and erythema, particularly facial involvement
- Erythroderma: rare, severe generalized form (seborrheic erythroderma), more common in infants or immunocompromised adults
- Chronic relapsing course: adult disease typically persists for years with flares and remissions; it is not curable but is well controlled with maintenance therapy
- Infantile cradle cap has an excellent prognosis with spontaneous resolution within the first year of life
"SCALP" sites: Scalp, Chest (presternal), Alae nasi/nasolabial folds, Lids/brows (eyebrows), Posterior ears (retroauricular)
Practice questions
1. A 34-year-old man presents with greasy, yellow scaling patches on his scalp, eyebrows, and nasolabial folds for several months. He reports mild itching but no joint pain or nail changes. He has no significant past medical history. Which of the following best describes the underlying pathophysiology of his condition?
2. A 45-year-old man with a history of intravenous drug use presents with severe, widespread, treatment-resistant seborrheic dermatitis involving the scalp, face, and trunk. Which of the following is the most appropriate next step?
3. A 2-month-old infant is brought in with thick, greasy yellow scale on the scalp. The infant is feeding well, gaining weight appropriately, and has no other skin findings or systemic symptoms. Which of the following is the most appropriate management?
Frequently asked questions
What causes seborrheic dermatitis?
Seborrheic dermatitis is caused by an abnormal inflammatory skin reaction to Malassezia yeast, a normal skin organism, combined with increased sebum production in genetically susceptible individuals. Risk factors include immunosuppression (especially HIV), Parkinson disease, cold weather, and stress. It is not caused by poor hygiene or a true skin infection.
What are the first symptoms of seborrheic dermatitis?
The earliest symptoms are usually mild scalp flaking (dandruff) or greasy, yellowish scale with redness on the scalp, eyebrows, or around the nose. Mild itching is common. In infants, it presents as thick, greasy scale on the scalp known as cradle cap, usually within the first few months of life.
How is seborrheic dermatitis diagnosed?
Seborrheic dermatitis is diagnosed clinically based on the typical appearance and distribution of greasy, scaly, erythematous patches in sebaceous areas like the scalp and face. No blood test or biopsy is usually needed. Biopsy is reserved for atypical or treatment-resistant cases to rule out psoriasis or other skin conditions.
Is seborrheic dermatitis curable?
Seborrheic dermatitis is not curable but is highly manageable with ongoing treatment. It is a chronic, relapsing condition, meaning symptoms typically return after stopping treatment, so most adults need intermittent maintenance therapy with antifungal shampoos or creams. Infantile cradle cap, however, usually resolves on its own within the first year of life.
Seborrheic dermatitis vs psoriasis — what is the difference?
Seborrheic dermatitis causes thinner, greasy yellow scale mainly on the scalp and face, while psoriasis causes thicker, well-demarcated silvery-white plaques often on extensor surfaces like elbows and knees, and may involve nail pitting. The two conditions can overlap, a presentation called sebopsoriasis, making clinical distinction sometimes difficult.
Key drugs
Related conditions and differentials
Sources and further reading
StatPearls (NCBI Bookshelf)MedlinePlusWHO ICD-10: L21
Educational content for medical students, prepared by the WhiteCoat Pro editorial team with AI assistance; every page is reviewed by a second AI model for factual errors. It is not medical advice and does not replace the product label, local guidelines or a clinician.