What is the treatment for ringworm (tinea infection) in a patient, considering factors such as location and severity of the infection, medical history, age, and immune status?

Treatment of Ringworm (Tinea Infections)

For tinea corporis (body) and tinea cruris (groin), topical antifungal therapy is first-line treatment for localized disease, while oral antifungals are required for tinea capitis (scalp), extensive infections, or treatment failures. 1, 2, 3

Topical Treatment for Localized Tinea Corporis and Tinea Cruris

Apply topical antifungals for 2-4 weeks, continuing at least one week after clinical clearing:

• Terbinafine 1% cream once or twice daily for 1-2 weeks is highly effective and requires shorter treatment duration 4, 5
• Naftifine 1% cream once daily achieves mycological cure in 3 out of 4 patients (RR 2.38, NNT 3) 4
• Clotrimazole 1% cream twice daily is effective with mycological cure rates nearly 3 times higher than placebo (RR 2.87, NNT 2) 4
• Other azole options (miconazole, ketoconazole) applied twice daily for 2-4 weeks are equally effective 4, 5

Critical pitfall: Avoid combination antifungal-corticosteroid creams as first-line therapy despite their faster symptom relief, as they may mask infection and promote resistance 6, 4

Oral Treatment Indications

Switch to oral therapy when: 1, 2, 3

• Topical treatment fails after 2-4 weeks
• Infection is extensive or involves hair follicles
• Patient is immunocompromised
• Tinea capitis is present (oral therapy always required)

Oral Antifungal Regimens

For Tinea Corporis/Cruris (Body/Groin)

Terbinafine 250 mg daily for 2-4 weeks is preferred for Trichophyton species (most common cause) 1, 2

Itraconazole 100 mg daily for 15 days is the alternative, particularly effective for mixed or Microsporum infections with 87% mycological cure rate 1, 2

For Tinea Capitis (Scalp)

The treatment choice depends on the causative organism: 7

For Trichophyton species (T. tonsurans, T. violaceum):

• Terbinafine is first-line: 7
  • <20 kg: 62.5 mg daily for 2-4 weeks
  • 20-40 kg: 125 mg daily for 2-4 weeks

  • 40 kg: 250 mg daily for 2-4 weeks

For Microsporum species (M. canis, M. audouinii):

• Griseofulvin is first-line: 7, 3
  • <50 kg: 15-20 mg/kg/day for 6-8 weeks (take with fatty food to enhance absorption)

  • 50 kg: 1 g daily for 6-8 weeks

  • This is the only FDA-approved treatment for tinea capitis in children 3

Second-line option for either organism:

• Itraconazole 5 mg/kg/day for 2-4 weeks (not licensed in UK for children ≤12 years but widely used) 7

Essential Adjunctive Measures

To prevent transmission and reinfection: 7, 1, 2

• Use antifungal shampoos (ketoconazole 2%, selenium sulfide 1%, or povidone-iodine) twice weekly to reduce spore shedding 7
• Screen and treat all family members, as >50% may be infected with anthropophilic species like T. tonsurans 1, 2
• Clean all contaminated items (combs, brushes, towels) with 2% sodium hypochlorite solution or disinfectant 1, 2
• Children on appropriate therapy can attend school/nursery 7

Treatment Monitoring

The endpoint is mycological cure, not just clinical improvement: 1, 2

• Obtain KOH preparation or fungal culture before starting treatment to confirm diagnosis 2, 3
• Repeat mycology sampling until clearance is documented 7, 1, 2
• For treatment failure with initial clinical improvement but persistent positive cultures, continue current therapy for an additional 2-4 weeks 7
• For complete treatment failure, switch to second-line agent 7

Management of Treatment Failure

If no clinical improvement after standard duration: 7

• First assess compliance, drug absorption, and potential reinfection 7
• For Trichophyton infections failing terbinafine: switch to itraconazole 7
• For Microsporum infections failing griseofulvin: switch to itraconazole 7
• Consider extending treatment duration to 6-12 months for resistant cases 7

Safety Considerations

Adverse effects are generally mild: 2

• Gastrointestinal symptoms occur in <8% of patients 2
• Treatment discontinuation required in only 0.8% of cases 2
• Itraconazole has significant drug interactions with warfarin, certain antihistamines (terfenadine, astemizole), midazolam, digoxin, and simvastatin 7

Common pitfall: Stopping treatment when lesions clear clinically without confirming mycological cure leads to relapse 1, 2