What is the recommended dosing of Terbinafine (generic name) for the treatment of ringworm (tinea infection)?

Terbinafine Dosing for Ringworm (Tinea Infections)

For ringworm (tinea infections), oral terbinafine should be dosed at 250 mg once daily for adults, with treatment duration varying by infection site: 1 week for tinea corporis/cruris, 2 weeks for tinea pedis, and 2-4 weeks for tinea capitis. 1

Dosing by Infection Type

Tinea Corporis/Cruris (Body/Groin Ringworm)

• Adults: 250 mg oral terbinafine once daily for 1-2 weeks 1, 2
• Children: Weight-based dosing
  • <20 kg: 62.5 mg daily
  • 20-40 kg: 125 mg daily

  • 40 kg: 250 mg daily

• Duration: 1-2 weeks is typically sufficient 2

Tinea Pedis (Athlete's Foot)

• Adults: 250 mg oral terbinafine once daily for 2 weeks 1, 3
• Children: Same weight-based dosing as above
• Duration: 2 weeks is typically sufficient, with faster clinical resolution compared to topical treatments 1

Tinea Capitis (Scalp Ringworm)

• Adults: 250 mg oral terbinafine once daily 1
• Children: Weight-based dosing 1
  • <20 kg: 62.5 mg daily
  • 20-40 kg: 125 mg daily

  • 40 kg: 250 mg daily

• Duration: 2-4 weeks, depending on causative organism 1
  • Trichophyton species: 2-4 weeks
  • Microsporum species: Less effective; griseofulvin preferred

Treatment Selection Considerations

Organism-Specific Efficacy

• Terbinafine is most effective against Trichophyton species infections (T. tonsurans, T. rubrum, T. mentagrophytes) 1
• For Microsporum infections, griseofulvin is generally more effective 1

Advantages of Terbinafine

• Once-daily dosing improves compliance 1
• Shorter treatment duration compared to topical treatments 1
• Faster clinical resolution compared to topical clotrimazole 4
• High mycological cure rates (93.5% for tinea pedis at 4 weeks) 4

Monitoring and Safety

• Well tolerated in children with side effects in <8% of cases 1
• Most common side effects: gastrointestinal disturbances and rashes 1
• Caution in patients with:
  • Hepatic impairment
  • Pre-existing liver disease
  • History of heavy alcohol consumption 5

Treatment Failure Considerations

• Consider the following if treatment fails:
  • Poor compliance
  • Suboptimal drug absorption
  • Relative insensitivity of the organism
  • Reinfection 1
• For clinical improvement but ongoing positive mycology, continue current therapy for an additional 2-4 weeks 1
• If no clinical improvement, consider alternative antifungals:
  • Itraconazole: 100 mg daily for 2 weeks or 5 mg/kg/day for 2-4 weeks 1
  • Fluconazole: As a third-line option 1

Important Caveats

• Increasing the dose to 500 mg daily does not provide additional benefit for tinea corporis/cruris 6
• Topical therapy alone is not recommended for tinea capitis 1
• Recent evidence suggests poor cure rates (20-33%) for tinea corporis/cruris after 4 weeks of treatment, even with higher doses 6
• For tinea pedis, 1 week of topical terbinafine 1% cream is more effective than 4 weeks of topical clotrimazole 1% cream 4

Remember that while terbinafine is highly effective for most tinea infections, treatment should be tailored based on the causative organism and infection site to achieve optimal clinical outcomes.