Lamisil (Terbinafine Hydrochloride)

Lamisil is an allylamine antifungal used to treat superficial dermatophyte infections of the skin, hair and nails.

• Athlete's foot (tinea pedis): reduces fungal proliferation and relieves itching, scaling and redness.
• Ringworm (tinea corporis): clears skin lesions and prevents spread of infection.
• Jock itch (tinea cruris): alleviates irritation and eliminates the causative fungus.
• Nail fungus (tinea unguium): improves nail appearance by eradicating fungal growth in the nail plate.

• Terbinafine inhibits the fungal enzyme squalene epoxidase, a key step in the biosynthesis of ergosterol, an essential component of fungal cell membranes. By blocking ergosterol production, the drug causes accumulation of toxic squalene and destabilizes the membrane, leading to fungal cell death while sparing human cells.

Topical terbinafine may cause local and systemic adverse reactions, ranging from mild irritation to rare severe events.

Common Side Effects

• Application site irritation: redness, burning, or stinging at the site of use.
• Itching: mild pruritus may develop during treatment.
• Dryness or peeling: skin may become dry or flake.
• Erythema: mild redness around the treated area.

Serious or Rare Side Effects

• Allergic contact dermatitis: widespread rash, swelling, or hives requiring medical attention.
• Severe skin reactions: Stevens‑Johnson syndrome or toxic epidermal necrolysis, though extremely rare.
• Systemic toxicity: liver enzyme elevation or hepatitis in rare cases of extensive absorption.

When using Lamisil, consider the following precautions to ensure safe and effective therapy.

• Pregnancy: consult a healthcare professional before use, as safety data are limited.
• Breastfeeding: discuss potential risks with a physician, as terbinafine may be excreted in milk.
• Age: use with caution in children under 2 years; pediatric dosing should be guided by a prescriber.
• Liver disease: assess hepatic function before initiating therapy and monitor if pre‑existing liver conditions exist.
• Skin integrity: avoid applying to broken, inflamed, or mucous membranes.
• Store at room temperature: keep in the original packaging, protect from moisture and direct sunlight.

Terbinafine may interact with other medicines; known interactions are grouped by clinical significance.

Major Interactions (Avoid)

• CYP2D6 inhibitors (e.g., fluoxetine, paroxetine): may increase systemic terbinafine levels, raising risk of hepatotoxicity.
• Concurrent oral antifungals (e.g., itraconazole, fluconazole): combined use can exacerbate liver toxicity.

Moderate Interactions (Monitor Closely)

• Alcohol consumption: may potentiate liver enzyme elevations; monitor hepatic function.
• Warfarin: terbinafine can increase INR; regular coagulation monitoring is advised.
• Topical corticosteroids: may mask local irritation, requiring observation for worsening dermatitis.