Lamisil (Terbinafine Hydrochloride)

Lamisil (terbinafine) is indicated for fungal infections of the skin and nails, acting on dermatophyte organisms.

• Tinea pedis: reduces symptoms and eradicates the causative dermatophyte causing athlete’s foot.
• Tinea corporis: clears ringworm lesions on the body by eliminating the fungal infection.
• Tinea cruris: treats jock itch by targeting the responsible fungi and relieving inflammation.
• Onychomycosis: improves nail appearance and clears fungal infection of the toenails or fingernails.

• Terbinafine inhibits the fungal enzyme squalene epoxidase, a key step in ergosterol biosynthesis. Blockade of this enzyme leads to accumulation of toxic squalene within the fungal cell and depletion of ergosterol, an essential membrane component. The resulting disruption of cell membrane integrity causes fungal cell death, providing a fungicidal effect against dermatophytes and certain yeasts.

Topical terbinafine may cause local and systemic adverse reactions, most of which are mild and reversible.

Common Side Effects

• Itching: mild pruritus at the application site.
• Burning sensation: transient heat or stinging feeling.
• Redness: localized erythema around the treated area.
• Dryness: skin flaking or dryness near the site.

Serious or Rare Side Effects

• Contact dermatitis: allergic skin reaction with swelling and rash.
• Severe skin irritation: intense burning, swelling, or blistering.
• Systemic hypersensitivity: rare rash or urticaria beyond the application site.
• Stevens‑Johnson syndrome: extremely rare severe mucocutaneous reaction.

When using topical terbinafine, certain precautions should be observed to ensure safety and effectiveness.

• Application area: apply a thin layer to clean, dry skin and avoid excessive use.
• Duration of therapy: follow the prescriber’s recommended treatment length; premature discontinuation may lead to recurrence.
• Age restrictions: use in children only as directed by a healthcare professional.
• Concomitant skin conditions: avoid use on severely inflamed, broken, or infected skin not caused by dermatophytes.
• Store at ambient temperature: keep the product below 25°C in the original packaging, protected from moisture and direct sunlight.

Topical terbinafine has a low potential for drug interactions, but certain substances may affect its safety or efficacy.

Major Interactions (Avoid)

• Systemic antifungals: concurrent use of oral terbinafine or other systemic antifungals may increase risk of systemic toxicity.
• CYP2D6 inhibitors: strong inhibitors could theoretically raise systemic exposure if significant absorption occurs.

Moderate Interactions (Monitor Closely)

• Alcohol: excessive intake may exacerbate rare liver effects.
• Topical corticosteroids: combined use may alter skin absorption and increase irritation.
• Warfarin: monitor coagulation parameters if long‑term extensive use is planned, although interaction is uncommon.