Lamisil (terbinafine hydrochloride) is a leading oral and topical antifungal medication indicated for the treatment of dermatophytic onychomycosis and tinea infections. As a potent allylamine antifungal, it works by inhibiting squalene epoxidase, a key enzyme in ergosterol synthesis, effectively disrupting fungal cell membrane integrity. With over three decades of clinical use and extensive research supporting its efficacy, Lamisil remains a first-line therapeutic choice for fungal infections. This comprehensive guide provides healthcare professionals and informed patients with detailed information regarding its proper use, mechanism, and safety profile.

Features

• Contains terbinafine hydrochloride as the active pharmaceutical ingredient
• Available in 250 mg oral tablets and 1% topical formulations (cream, solution, spray)
• Exhibits fungicidal activity against dermatophytes such as Trichophyton species
• Demonstrated bioavailability of approximately 70-80% following oral administration
• Topical formulations designed for enhanced skin and nail penetration
• Manufactured under strict pharmaceutical quality control standards

Benefits

• Achieves clinical cure rates of 70-85% in onychomycosis when used as directed
• Provides rapid symptomatic relief from itching, scaling, and inflammation
• Prevents recurrence by eradicating fungal reservoirs in nail beds and skin
• Offers convenient once-daily dosing for improved treatment adherence
• Reduces risk of secondary bacterial infections through comprehensive antifungal action
• Minimizes treatment duration compared to older antifungal agents

Common use

Lamisil is primarily prescribed for the treatment of onychomycosis of the toenails or fingernails caused by dermatophytes. Additionally, it is indicated for tinea corporis (ringworm), tinea cruris (jock itch), tinea pedis (athlete’s foot), and tinea versicolor. The oral formulation is typically reserved for moderate to severe cases or when topical therapy has proven insufficient. Topical formulations are appropriate for localized, superficial infections without nail involvement. Diagnosis should be confirmed by potassium hydroxide (KOH) preparation or fungal culture before initiating treatment.

Dosage and direction

Oral tablets:
Adults: 250 mg once daily
Fingernail onychomycosis: 6 weeks duration
Toenail onychomycosis: 12 weeks duration

Topical formulations:
Apply once or twice daily to affected area and surrounding skin
Clean and dry area before application
Continue treatment for 1-2 weeks after symptoms resolve
Nail formulations: Apply to affected nails once daily

Administration with food may minimize gastrointestinal discomfort. Complete the full course of therapy even if symptoms improve earlier to prevent recurrence.

Precautions

Monitor liver function tests (LFTs) before and during treatment. Use with caution in patients with pre-existing liver disease or hepatic impairment. Regular complete blood counts recommended during extended therapy. May cause taste disturbance that usually resolves upon discontinuation. Topical application may cause local irritation; discontinue if severe reaction occurs. Not recommended during pregnancy unless clearly needed. Breastfeeding should be discontinued during oral therapy.

Contraindications

Hypersensitivity to terbinafine or any component of the formulation. Chronic or active liver disease. Severe renal impairment (creatinine clearance <50 mL/min). History of drug-induced liver injury. Concurrent use with specific CYP2D6 substrates with narrow therapeutic indices.

Possible side effect

Common (>1%): Headache, gastrointestinal disturbances (nausea, diarrhea, dyspepsia), rash, pruritus, taste disturbance
Less common: Elevated liver enzymes, visual disturbances, dizziness, fatigue
Rare but serious: Hepatotoxicity, severe skin reactions (Stevens-Johnson syndrome), blood dyscrasias, depression
Topical: Local burning, itching, irritation at application site

Drug interaction

Potent inhibitor of CYP2D6: May increase concentrations of beta-blockers, SSRIs, TCAs, and antiarrhythmics. Rifampin reduces terbinafine concentrations. Cimetidine increases terbinafine concentrations. May interact with other hepatotoxic drugs. Monitor patients on warfarin therapy closely.

Missed dose

Take the missed dose as soon as remembered unless it is nearly time for the next dose. Do not double the dose to make up for a missed one. Maintain regular dosing schedule to ensure consistent therapeutic levels.

Overdose

Symptoms may include nausea, vomiting, abdominal pain, dizziness, and headache. In case of suspected overdose, provide supportive care including gastric lavage if presented early. Activated charcoal may be beneficial. No specific antidote exists. Monitor hepatic and renal function in significant overdose.

Storage

Store at room temperature (15-30°C/59-86°F). Keep container tightly closed. Protect from light and moisture. Do not freeze. Keep out of reach of children and pets. Do not use after expiration date.

Disclaimer

This information is for educational purposes only and does not replace professional medical advice. Consult a healthcare provider for proper diagnosis and treatment recommendations. Individual response to medication may vary. Report any adverse effects to your physician immediately.

Reviews

“After struggling with persistent toenail fungus for years, Lamisil tablets provided complete clearance. Required regular monitoring but worth the results.” - Podiatrist, 15 years experience

“Our clinical practice consistently observes superior mycological cure rates with terbinafine compared to azole antifungals for dermatophyte infections.” - Dermatology Department, University Hospital

“Topical Lamisil solution effectively manages mild tinea pedis in most patients with minimal side effects. First-line choice in our clinic.” - Primary Care Physician