Asymptomatic hepatotoxicity following exposure to oral terbinafine for onychomycosis treatment

Hepatotoxicity is a known but very rare side effect of oral terbinafine therapy. To our knowledge, there are no reported cases of patients with cleared hepatitis B infection prescribed oral terbinafine. We report an 82-year-old woman with previous hepatitis B exposure who experienced asymptomatic elevation of aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase levels following 28 days of therapy with 250mg of oral terbinafine daily for onychomycosis treatment. After drug discontinuation, her liver function tests returned to baseline about three months later, without permanent liver damage. Oral terbinafine therapy, although typically efficacious and well-tolerated for onychomycosis treatment, rarely causes hepatoxicity. Physician knowledge of this rare but important side effect is necessary to prevent morbidity and mortality resulting from continued therapy. Oral terbinafine therapy might not reactivate hepatitis B in patients with past infection.