Lamisil Once (Terbinafine)

Terbinafine treats dermatophyte skin infections by inhibiting ergosterol synthesis, thereby disrupting fungal cell membranes and halting growth.

• Tinea pedis (athlete’s foot): reduces itching, redness and scaling while eliminating the causative dermatophyte on the feet.
• Tinea corporis (ringworm of the body): promotes disappearance of circular, erythematous lesions and prevents spread to adjacent skin.
• Tinea cruris (jock itch): alleviates irritation in the groin and inner thigh region and clears the fungal infection.

• Terbinafine acts by selectively inhibiting the fungal enzyme squalene epoxidase, a critical step in ergosterol biosynthesis. The resulting accumulation of squalene and depletion of ergosterol compromise fungal cell‑membrane integrity, leading to cell death. This mechanism primarily targets dermatophytes, molds and yeasts while sparing human cells.

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

Common Side Effects

• Burning sensation at the application site.
• Itching or mild rash.
• Redness or irritation of the skin.
• Dryness or peeling of the treated area.

Serious or Rare Side Effects

• Severe allergic reaction (e.g., angioedema, anaphylaxis).
• Hepatotoxicity manifesting as jaundice or elevated liver enzymes.
• Blood disorders such as neutropenia or agranulocytosis.
• Unexplained fever or systemic illness.

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

• Contraindication: avoid use in individuals with known hypersensitivity to terbinafine or other allylamine antifungals.
• Caution: assess liver function before initiating therapy in patients with pre‑existing hepatic disease.
• Pregnancy: use only if the potential benefit outweighs the risk, as safety data are limited.
• Breastfeeding: consult a healthcare professional before use, as drug may be excreted in milk.
• Application: apply a thin layer to clean, dry skin and avoid contact with eyes or mucous membranes.
• Store at ambient temperature: keep in the original packaging, protect from moisture and direct sunlight.

Terbinafine can interact with other medicines; awareness of significant interactions helps prevent reduced efficacy or increased toxicity.

Major Interactions (Avoid)

• Concomitant use with potent CYP2D6 inhibitors (e.g., fluoxetine, paroxetine) may increase terbinafine plasma levels.
• Co‑administration with drugs that are highly protein‑bound may displace terbinafine, altering its distribution.

Moderate Interactions (Monitor Closely)

• Use with other hepatotoxic agents (e.g., isoniazid, methotrexate) requires liver function monitoring.
• Concurrent systemic antifungals may increase risk of adverse skin reactions.
• Anticoagulants such as warfarin may have altered effect; monitor INR.
• St. John’s wort may reduce terbinafine exposure; advise patients of potential reduced efficacy.