Questionnaire/history: Rash at: - Scalp (dandruff)? - Nasolabial folds? - Eyebrows? - Behind the ears? - Upper chest? Mild itch (particularly at scalp)? Onset? Evolution? (Note: infantile seborrheic dermatitis usually appearing between the 2nd week and 6th month (mostly btw 3rd and 8th week) with mild itch and resolving within weeks to several months) Past medical history? Current medication? Drug allergies? Examination: Relatively well-defined patches of erythema associated with flaking of the skin (scales may be white or yellow, oily or dry)? (Note: in darker skin affected areas may appear hypo or hyperpigmented compared to surrounding skin) Symmetrically distributed lesions (with usually one or two body areas being affected but signs may be more widespread)? Scalp? - Mild desquamation (dandruff)? - Thick brownish crusts adherent to skin and hair? Face (in particular the nasolabial folds, glabellar area, eyebrows, and behind the ears)? - Eyelids red, swollen and flaky (seborrheic blepharitis)? - Ear canals, cup of the ear and skin behind the ears inflamed? - Beard area? Upper chest and back? - In men petal-shaped lesions typically develop on the presternal area (petaloid type)? - Generalized macules and patches that resemble extensive pityriasis rosea (pityriasiform type (less common))? Flexures and skin folds? - Axillae? - Infra-mammary area? - Umbilicus? - Groin? - Anogenital area? - Maceration and intertrigo? - Skin glazed and pink? In infants: Yellow-brown, large and greasy scales on the scalp (cradle cap)? Drier, smaller and whiter scales with well-defined areas of erythema and scaling with tiny vesicles? - Face? - Ears? - Neck? - Flexural folds? Images Differential diagnosis Management Reference(s): NICE CKS: Seborrheic dermatitis Information for patient/carer(s): British Association of Dermatologists: Seborrheic dermatitis National Eczema Association: Seborrheic dermatitis