| Drug class |
Allylamine antifungal (inhibits fungal squalene epoxidase) |
| Common uses |
• Onychomycosis (fungal nail infection) – usually 250 mg once daily for 6–12 weeks (for toes) or 12–24 weeks (for fingers)
• Tinea (athlete’s foot, ringworm, jock itch) – 250 mg once daily for 2–4 weeks |
| Formulations |
Oral tablets (250 mg) and topical creams/gels (typically 1 % or 2 % concentration) |
| How it works |
Inhibits the fungal enzyme squalene epoxidase, disrupting the synthesis of ergosterol (a key component of fungal cell membranes) and leading to accumulation of squalene, which is toxic to the fungus. |
| Key benefits |
• Oral terbinafine has high cure rates (70–90 % for toenail infections).
• Generally well tolerated when taken as directed. |
| Typical side‑effects |
• Gastro‑intestinal: nausea, diarrhea, abdominal pain (often mild and transient).
• Taste disturbances (taste loss or metallic taste).
• Rarely: rash, headache, dizziness, fatigue.
• Very rare: liver injury (monitor liver enzymes if you have risk factors). |
| Drug interactions |
• CYP2D6 inhibitors (e.g., fluoxetine, paroxetine) can raise terbinafine levels.
• Other medications processed by CYP2D6 may have altered levels (e.g., certain antidepressants, beta‑blockers).
• Cimetidine may increase terbinafine levels.
• Other antifungals (especially azoles) should generally be avoided concurrently. |
| Precautions |
• Liver disease: baseline ALT/AST testing recommended; repeat during therapy if elevated.
• Pregnancy: classified as Category B; use only if clearly needed and no safer alternative.
• Kidney function: usually fine; dosage adjustment mainly for liver function.
• Elderly: start at standard dose but monitor for side‑effects. |
| Monitoring |
• For long‑term use (>4 weeks), many clinicians check liver function tests every 2–4 weeks.
• If you experience severe GI upset, rash, or jaundice, stop and seek medical advice. |
| How to take it |
• Take with food or a full glass of milk to improve absorption and reduce stomach upset.
• Avoid taking with grapefruit juice, which can increase absorption and risk of side‑effects.
• Stick to the prescribed duration; stopping early can lead to relapse. |
| After finishing |
• Nail infections take time to “grow back”; it may take 6–9 months for a completely healthy nail to re‑grow. |
| Alternatives |
• Azole antifungals (fluconazole, itraconazole) – often used for systemic infections.
• Topical antifungals (clotrimazole, ketoconazole) for mild skin infections.
• Efinaconazole (another topical nail antifungal). |