Lamisil (Terbinafine Hydrochloride)

Lamisil (terbinafine) is used to treat superficial dermatophyte infections of the skin.

• Tinea pedis (athlete's foot): reduces fungal growth and relieves itching and scaling.
• Tinea corporis (ringworm): clears lesions and prevents spread.
• Tinea cruris (jock itch): eliminates infection and improves comfort.
• Tinea versicolor: restores normal skin coloration by eradicating yeast.
• Superficial dermatophyte infections: provides broad‑spectrum topical antifungal activity.

• Terbinafine inhibits the fungal enzyme squalene epoxidase, a key step in the biosynthesis of ergosterol, an essential component of fungal cell membranes. By blocking this pathway, intracellular squalene accumulates to toxic levels while ergosterol depletion disrupts membrane integrity, leading to fungal cell death. The selective inhibition of the enzyme in fungi results in minimal effect on human cells.

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

Common Side Effects

• Itching or mild burning at the application site.
• Redness or erythema of the skin.
• Dryness or peeling of the treated area.
• Stinging sensation shortly after application.

Serious or Rare Side Effects

• Severe allergic reaction (angioedema, swelling, difficulty breathing).
• Contact dermatitis with blistering or swelling.
• Hepatotoxicity manifested by jaundice or abnormal liver tests (rare with topical use).

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

• Avoid application on broken or inflamed skin: limit use to intact epidermis.
• Do not use on mucous membranes or eyes: these areas are sensitive to irritation.
• Limit treatment duration: follow prescriber’s recommended course, typically up to 4 weeks.
• Monitor for signs of allergic reaction: discontinue and seek medical advice if severe rash develops.
• Use caution in patients with known liver disease: although systemic absorption is low, report any hepatic symptoms.
• Store at ambient temperature: keep in the original container, protect from moisture and heat.

Topical terbinafine can interact with certain systemic medications and topical agents.

Major Interactions (Avoid)

• Concurrent use with oral terbinafine: may increase systemic exposure and risk of hepatotoxicity.
• Application over large body surface combined with systemic antifungals: can lead to additive toxicity.

Moderate Interactions (Monitor Closely)

• Use with other topical irritants (e.g., corticosteroids, retinoids): may increase skin irritation.
• Co‑administration with drugs metabolized by CYP2D6 (e.g., certain antidepressants): terbinafine can inhibit the enzyme, potentially altering plasma levels.
• Interaction with alcohol: excessive intake may exacerbate liver stress when systemic absorption occurs.