Indications: dermatophyte infections of the skin, scalp, hair and nails where topical therapy has failed or is inappropriate.

Contra-indications: severe liver disease; systemic lupus erythematosus (risk of exacerbation); porphyria; pregnancy (avoid pregnancy during and for 1 month after treatment; men should not father children within 6 months of treatment); breast-feeding.

Side Effects: nausea, vomiting, diarrhoea; headache; less frequently hepatotoxicity, dizziness, confusion, fatigue, sleep disturbances, impaired co-ordination, peripheral neuropathy, leucopenia, systemic lupus erythematosus, rash (including rarely erythema multiforme, toxic epidermal necrolysis), and photosensitivity.

Dose: Dermatophyte infections, 500 mg once daily or in divided doses; in severe infection dose may be doubled, reducing when response occurs; CHILD under 50 kg, 10 mg/kg once daily or in divided doses.

Tinea capitis caused by Trichophyton tonsurans, 1 g once daily or in divided doses; CHILD under 50 kg, 15–20 mg/kg once daily or in divided doses.