Lamisil (Terbinafine Hydrochloride)

Lamisil is used to treat dermatophyte infections of the skin and superficial structures.

• Tinea corporis (ringworm): eliminates the fungal infection on the body, reducing redness and scaling.
• Tinea pedis (athlete’s foot): clears the infection between the toes and on the soles, relieving itching and burning.
• Tinea cruris (jock itch): resolves the fungal rash in the groin area, improving comfort and preventing spread.
• Other superficial dermatophyte infections: treats infections such as onychomycosis of the nail surface and other cutaneous fungal conditions.

• Terbinafine Hydrochloride acts by inhibiting the fungal enzyme squalene epoxidase, a key step in the biosynthesis of ergosterol, an essential component of fungal cell membranes. Blockade of this pathway leads to accumulation of toxic squalene and depletion of ergosterol, disrupting membrane integrity and causing fungal cell death. This mechanism provides a fungicidal effect that is effective with short treatment courses.

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

Common Side Effects

• Skin irritation: mild redness, itching, or burning at the application site.
• Pruritus: transient itching unrelated to infection.
• Erythema: localized redness of the treated skin.
• Dryness: occasional peeling or flaking of the skin.

Serious or Rare Side Effects

• Allergic contact dermatitis: severe rash, swelling, or blistering requiring medical attention.
• Hepatotoxicity: rare systemic absorption leading to liver enzyme elevation.
• Stevens‑Johnson syndrome: extremely rare but life‑threatening skin reaction.
• Anaphylaxis: rare systemic allergic response with respiratory distress.

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

• Application area: apply a thin layer only to affected skin and avoid healthy surrounding tissue.
• Duration of therapy: follow the prescriber’s recommended treatment length and do not exceed it.
• Age restrictions: use in children only as directed by a healthcare professional; avoid use in infants without guidance.
• Concomitant skin conditions: avoid application on eczematous, ulcerated, or infected skin not caused by dermatophytes.
• Pregnancy and lactation: discuss use with a physician; terbinafine is generally avoided unless benefits outweigh risks.
• Store at room temperature: keep the product in its original container, protect from moisture and direct sunlight.

Terbinafine can interact with other medicines, altering its efficacy or increasing the risk of adverse effects.

Major Interactions (Avoid)

• Cytochrome P450 2D6 inhibitors: may increase systemic exposure to terbinafine, raising toxicity risk.
• Antifungal agents with overlapping toxicity: concurrent use with itraconazole or ketoconazole can enhance hepatotoxic potential.
• Warfarin: terbinafine may potentiate anticoagulant effect, requiring close monitoring of INR.

Moderate Interactions (Monitor Closely)

• Oral contraceptives: terbinafine may reduce hormonal efficacy, consider alternative contraception.
• Rifampin: may decrease terbinafine levels, reducing antifungal effectiveness.
• Alcohol: excessive intake can increase liver strain when combined with terbinafine.