Onychomed (Terbinafine Hydrochloride)

Terbinafine is an antifungal agent that acts on dermatophyte infections of the skin, nail and hair.

• Onychomycosis: Improves nail appearance and reduces fungal load.
• Tinea pedis (athlete’s foot): Relieves scaling and itching.
• Tinea corporis (ringworm): Clears skin lesions and prevents spread.
• Tinea cruris (jock itch): Reduces erythema and pruritus.
• Tinea capitis: Eliminates scalp fungal infection in children.
• Seborrheic dermatitis: Decreases flaking and redness.

• Terbinafine inhibits the fungal enzyme squalene epoxidase, disrupting the synthesis of ergosterol, an essential component of fungal cell membranes. This blockage leads to accumulation of squalene, which is toxic to the fungi, and results in cell death, providing a fungicidal effect against dermatophytes and some yeasts.

Terbinafine is generally well‑tolerated, but adverse reactions can occur.

Common Side Effects

• Gastrointestinal upset: nausea, abdominal discomfort.
• Skin reactions: mild rash or pruritus.
• Headache: transient and usually mild.
• Taste disturbance: temporary loss of taste sensation.
• Elevated liver enzymes: mild, reversible changes.

Serious or Rare Side Effects

• Hepatotoxicity: signs of liver injury such as jaundice.
• Severe skin reactions: Stevens‑Johnson syndrome or toxic epidermal necrolysis.
• Blood disorders: neutropenia or agranulocytosis.
• Peripheral neuropathy: tingling or numbness in extremities.
• Anaphylaxis: acute allergic reaction requiring emergency care.

Before prescribing Terbinafine, clinicians should assess liver function and potential drug interactions.

• Liver function monitoring: baseline and periodic tests recommended.
• Alcohol consumption: limit intake to reduce hepatic stress.
• Pregnancy and lactation: avoid unless benefits outweigh risks.
• Age considerations: use caution in elderly patients with comorbidities.
• Concomitant medications: review for CYP2D6 substrates.
• Store at ambient temperature: keep in original container, protect from moisture and direct sunlight.

Terbinafine may affect the metabolism of several co‑administered medicines.

Major Interactions (Avoid)

• Cimetidine: may increase terbinafine plasma levels.
• Itraconazole: combined use raises risk of hepatotoxicity.
• Rifampicin: reduces terbinafine effectiveness.

Moderate Interactions (Monitor Closely)

• Warfarin: may enhance anticoagulant effect.
• Oral contraceptives: possible reduction in efficacy.
• Antidepressants (SSRIs): monitor for QT‑prolongation.
• Antiretrovirals (protease inhibitors): adjust dosing if needed.
• Statins: observe liver function during combined therapy.