Treatment: terbinafine

Laboratory tests

• AST
• ALT
• GGT
• Alkaline phosphatase

Mycological sample

• Mycological sample from a nail (direct examination and culture) (onychomycosis suspected)if neededTo be requested before oral treatment for a presumed nail disorder: clinical diagnosis is misleading (only about one nail abnormality in two is a fungal infection ^[1]), and oral treatment can cause liver damage ^[2]. The SFD consensus (2007) asks for a mycological sample before any treatment, after a 3-month treatment-free window in case of previous systemic treatment ^[3]; SFD (2026) considers it preferable before prolonged treatment, clinical diagnosis alone sometimes being insufficient for non-dermatologists ^[1].
• Mycological sample from skin or scalp (direct examination and culture) (dermatophytosis or tinea capitis suspected)if neededTo be requested if tinea capitis or dermatophytosis is suspected: ANSM, with the learned societies, recommends a mycological sample as soon as possible when tinea capitis is suspected, terbinafine being startable straight away without waiting for the result ^[4].

Laboratory tests

• AST
• ALT
• GGT
• Alkaline phosphatase
• FBC (if fever, sore throat or infection without apparent cause, or sign suggesting haematological involvement)if neededFever, sore throat or other persistent infection with no apparent cause on terbinafine: the SmPC (RCP) asks to stop treatment and consult; very rare neutropenia, agranulocytosis, thrombocytopenia and pancytopenia are reported, to be investigated if they occur ^[2].
• Serum creatinine with eGFR (if known or suspected renal impairment)if neededThe SmPC (RCP) does not recommend terbinafine if creatinine clearance is < 50 mL/min and contraindicates it if < 30 mL/min ^[2]; to be checked in older people or in case of kidney disease.