Lamisil: Clinically Proven Antifungal Treatment for Onychomycosis
Lamisil
Lamisil (terbinafine hydrochloride) is a leading oral and topical antifungal medication indicated for the treatment of dermatophytic onychomycosis of the toenail or fingernail due to dermatophytes. As a member of the allylamine class of antifungals, it works by inhibiting squalene epoxidase, a key enzyme in ergosterol biosynthesis, resulting in fungicidal activity against susceptible organisms. With over three decades of clinical use and extensive research supporting its efficacy, Lamisil remains a first-line therapeutic option for fungal nail infections. Its systemic formulation demonstrates superior mycological cure rates compared to topical alternatives, particularly in moderate to severe cases involving the nail matrix.
Features
- Contains terbinafine hydrochloride as the active pharmaceutical ingredient
- Available in 250 mg oral tablets and 1% topical formulations (cream, solution, spray)
- Demonstrated fungicidal activity against Trichophyton species, Microsporum species, and Epidermophyton floccosum
- High bioavailability with approximately 70-80% oral absorption unaffected by food
- Extensive tissue distribution with high concentrations in nail plates within weeks of initiation
- Manufactured under current Good Manufacturing Practices (cGMP) standards
Benefits
- Achieves complete mycological cure in approximately 70-80% of patients with dermatophytic onychomycosis
- Promotes healthy nail regrowth by eliminating the fungal infection at the source
- Prevents spread of infection to other nails or household contacts
- Reduces risk of secondary bacterial infections and associated complications
- Minimizes nail disfigurement and associated psychosocial distress
- Offers convenient once-daily dosing regimen for improved adherence
Common use
Lamisil is primarily prescribed for the treatment of onychomycosis (fungal nail infections) caused by susceptible dermatophytes. The oral formulation is typically reserved for moderate to severe cases involving the nail matrix, while topical preparations are indicated for mild to moderate distal lateral subungual onychomycosis affecting less than 50% of the nail plate. Off-label uses include treatment of tinea corporis (ringworm), tinea cruris (jock itch), and tinea pedis (athlete’s foot) when topical therapy alone is insufficient. Clinical assessment should include potassium hydroxide (KOH) preparation or fungal culture to confirm dermatophytic infection before initiation of therapy.
Dosage and direction
Oral tablets: The recommended dosage for adults is 250 mg once daily. For fingernail infections: treatment duration is 6 weeks. For toenail infections: treatment duration is 12 weeks. Take with or without food, preferably at the same time each day.
Topical formulations: Apply a thin layer to affected nails and surrounding skin once or twice daily as directed. Before application, clean and dry the affected area thoroughly. For nail solutions, file away loose nail material and smooth rough edges with provided file. Wash hands after application unless treating hands.
Continue treatment for the full prescribed duration even if symptoms improve earlier. Clinical improvement may not be visible until several months after treatment completion due to slow nail growth.
Precautions
- Complete blood count and liver function tests should be performed before initiating oral therapy and periodically during treatment
- Monitor for symptoms of hepatotoxicity (fatigue, anorexia, nausea, vomiting, right upper quadrant pain, dark urine, pale stools)
- Use with caution in patients with pre-existing liver disease or hepatic impairment
- May cause taste disturbance (dysgeusia) that usually resolves upon discontinuation
- Topical formulations: avoid contact with eyes, nose, mouth, and other mucous membranes
- Do not use occlusive dressings unless directed by healthcare provider
- Discontinue if hypersensitivity reactions occur
Contraindications
- Hypersensitivity to terbinafine, any other allylamine antifungals, or any component of the formulation
- Chronic or active liver disease
- Severe renal impairment (creatinine clearance less than 50 mL/min)
- Pregnancy and breastfeeding (oral formulation)
- History of drug-induced blood dyscrasias
Possible side effects
Common (≥1/100):
- Headache
- Gastrointestinal disturbances (diarrhea, dyspepsia, nausea, abdominal pain)
- Taste disturbance
- Rash
- Pruritus
- Urticaria
Uncommon (≥1/1000):
- Liver enzyme elevations
- Visual disturbances
- Dizziness
- Fatigue
- Myalgia
- Arthralgia
Rare (<1/1000):
- Severe cutaneous adverse reactions (Stevens-Johnson syndrome, toxic epidermal necrolysis)
- Hepatobiliary dysfunction (including liver failure)
- Blood dyscrasias (neutropenia, agranulocytosis, thrombocytopenia)
- Panhypoproteinemia
- Depression
- Psoriasis flare or precipitation
Drug interaction
- Terbinafine is a moderate inhibitor of CYP2D6; use caution with coadministration of CYP2D6 substrates (tricyclic antidepressants, selective serotonin reuptake inhibitors, beta-blockers, antiarrhythmics)
- May reduce metabolism and increase plasma concentrations of dextromethorphan, desipramine, and other CYP2D6 substrates
- Rifampin (CYP450 inducer) decreases terbinafine plasma concentrations by 100%
- Cimetidine (CYP450 inhibitor) increases terbinafine plasma concentrations by 33%
- May reduce efficacy of oral contraceptives; recommend additional barrier contraception
- Coffee, caffeine-containing products may decrease terbinafine absorption
Missed dose
If a dose is missed, take it as soon as remembered unless it is almost time for the next scheduled dose. Do not double the dose to make up for a missed one. Resume regular dosing schedule. For topical formulations, apply missed dose when remembered unless close to next application time.
Overdose
Oral overdose: May manifest as dizziness, nausea, vomiting, abdominal pain. There is no specific antidote. Employ supportive measures including gastric lavage if presented within 1 hour of ingestion. Activated charcoal may be beneficial. Monitor hepatic and renal function, complete blood count. Terbinafine is not dialyzable.
Topical overdose: Unlikely to cause systemic effects due to minimal absorption. Wash affected area with soap and water. If accidental ingestion occurs, seek medical attention immediately.
Storage
Store at room temperature (15-30°C or 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 printed on packaging. Properly discard any unused medication after treatment completion.
Disclaimer
This information is for educational purposes only and does not constitute medical advice. Consult a healthcare professional for proper diagnosis and treatment recommendations. Individual results may vary. Full prescribing information is available from the manufacturer. Report any adverse events to your healthcare provider and the appropriate regulatory authority.
Reviews
Clinical studies demonstrate: In randomized controlled trials involving over 2,500 patients, oral terbinafine 250 mg daily for 12 weeks achieved mycological cure rates of 70-80% and complete cure rates of 35-50% in toenail onychomycosis. Long-term follow-up studies show sustained cure rates of approximately 70% at 5 years post-treatment.
Expert consensus: The American Academy of Dermatology guidelines position oral terbinafine as first-line therapy for dermatophytic onychomycosis based on its superior efficacy profile compared to other oral antifungals and topical agents. Dermatologists consistently report high patient satisfaction with treatment outcomes when proper patient selection and monitoring protocols are followed.
Patient-reported outcomes: Quality of life studies indicate significant improvement in emotional well-being, social functioning, and symptom burden following successful treatment with Lamisil. The convenience of once-daily dosing is frequently cited as a positive factor supporting treatment adherence.