Lamisil (Terbinafine)

Lamisil (terbinafine) is employed to treat superficial dermatophyte infections affecting the skin.

• Tinea pedis: reduces fungal growth and relieves itching and scaling on the feet.
• Tinea corporis: clears ring‑shaped lesions on the body by eradicating the causative dermatophytes.
• Tinea cruris: treats fungal infection of the groin area, diminishing redness and discomfort.
• Other superficial dermatophyte infections: resolves fungal involvement of nails, scalp or other skin sites when indicated.

• Terbinafine exerts its antifungal activity by inhibiting the enzyme squalene epoxidase, a key step in the ergosterol biosynthesis pathway of fungi. Blockade of this enzyme leads to accumulation of squalene, which is toxic to fungal cells, and a depletion of ergosterol, compromising cell‑membrane integrity and ultimately causing fungal cell death. The selective inhibition targets fungal cells while sparing human cholesterol synthesis, providing a favorable therapeutic index.

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

Common Side Effects

• Burning sensation: mild heat or stinging at the application site.
• Itching: transient pruritus around the treated area.
• Redness: localized erythema that usually resolves with continued use.
• Dryness or peeling: skin may become flaky or dry.
• Irritation: mild discomfort or rash limited to the site of application.

Serious or Rare Side Effects

• Severe allergic reaction: swelling, hives, or difficulty breathing indicating possible anaphylaxis.
• Contact dermatitis: intense redness, swelling, and blistering requiring discontinuation.
• Hepatotoxicity: rare systemic absorption leading to elevated liver enzymes.
• Stevens‑Johnson syndrome: extensive skin detachment and mucosal involvement, a medical emergency.
• Persistent ulceration: non‑healing skin breakdown at the application site.

Before using Lamisil, consider the following safety measures to minimize risks.

• Assess allergy: avoid use if known hypersensitivity to terbinafine or other allylamines.
• Limit duration: follow prescriber’s recommended treatment length to reduce irritation.
• Avoid broken skin: do not apply on extensive open wounds or severe dermatitis.
• Monitor liver function: patients with pre‑existing liver disease should have baseline tests.
• Pediatric use: use only under medical supervision in children as safety data are limited.
• Store at room temperature: keep below 25 °C, retain in original packaging, protect from moisture and direct sunlight.

Terbinafine can interact with other medicines, altering its efficacy or safety profile.

Major Interactions (Avoid)

• Cytochrome P450 inhibitors: concurrent strong CYP2D6 inhibitors may increase systemic terbinafine levels.
• Antifungal agents: combining with other systemic antifungals can raise risk of hepatotoxicity.
• Certain antidepressants: co‑administration with sertraline may enhance photosensitivity.

Moderate Interactions (Monitor Closely)

• Oral contraceptives: terbinafine may reduce hormonal efficacy; advise alternative contraception.
• Warfarin: monitor INR as terbinafine may potentiate anticoagulant effect.
• Rifampin: may decrease terbinafine concentrations, reducing antifungal activity.