What is the treatment for tinea and dermatophytes infections?

Antifungal Treatment for Tinea and Dermatophyte Infections

Oral antifungal therapy is absolutely required for tinea capitis and onychomycosis, while most localized skin infections (tinea corporis, cruris, pedis) respond to topical therapy alone unless extensive, recurrent, or in immunocompromised hosts. 1

Diagnostic Confirmation Before Treatment

Obtain mycological confirmation through KOH microscopy and fungal culture before initiating therapy whenever possible. 2, 1

• Collect specimens by scalp scraping, hair pluck, brush sampling, or swab for tinea capitis 2
• Use potassium hydroxide (10-30%) preparation for rapid microscopic diagnosis 2
• Culture on Sabouraud agar with cycloheximide for at least 2 weeks (3 weeks if T. verrucosum suspected from cattle exposure) 2
• Exception: Start treatment immediately without waiting for culture results if kerion, severe scaling, lymphadenopathy, or alopecia are present 2, 3

Treatment Algorithm by Anatomical Site

Tinea Capitis (Scalp Infections)

Topical therapy alone is completely ineffective and must never be used as monotherapy for tinea capitis. 2, 3

For Trichophyton Species:

Terbinafine is superior and preferred: 1, 3

• Children <20 kg: 62.5 mg daily for 2-4 weeks
• Children 20-40 kg: 125 mg daily for 2-4 weeks
• Children >40 kg and adults: 250 mg daily for 2-4 weeks

For Microsporum Species:

Griseofulvin is more effective and preferred: 1, 3, 4

• Children <50 kg: 15-20 mg/kg/day for 6-8 weeks
• Children >50 kg and adults: 1 g/day for 6-8 weeks 1
• FDA-approved dosing: 10 mg/kg daily (pediatric 30-50 lbs: 125-250 mg daily; >50 lbs: 250-500 mg daily) 4

Adjunctive Measures for Tinea Capitis:

• Screen all family members and close contacts, as >50% may be asymptomatic carriers of T. tonsurans 3
• Use antifungal shampoos (ketoconazole 2%, selenium sulfide 1%, or povidone-iodine) to reduce spore transmission 2
• Clean all fomites (combs, brushes, hats) with disinfectant or 2% sodium hypochlorite 3

Tinea Corporis, Cruris, and Pedis (Skin Infections)

Topical antifungal therapy is first-line for localized infections. 1, 5

Topical Therapy:

• Apply topical azoles (clotrimazole, miconazole) or allylamines (terbinafine) once or twice daily 6
• Allylamines have higher cure rates and shorter treatment courses than azoles 7
• Duration: Tinea corporis/cruris: 2-4 weeks; Tinea pedis: 4-6 weeks 6, 5
• Continue treatment for at least 1 week after clinical clearing 5

Oral Therapy (Reserved for Specific Situations):

Use oral therapy for extensive disease, treatment failure, or immunocompromised patients: 1

• Terbinafine: 250 mg daily for 1-2 weeks 1
• Itraconazole: 100 mg daily for 15 days (87% mycological cure rate) 1

Tinea Unguium (Onychomycosis)

Oral antifungal therapy is the treatment of choice, with terbinafine generally preferred over itraconazole due to superior efficacy and shorter duration. 1

First-Line: Terbinafine

• 250 mg daily 1
• Fingernail infections: 6 weeks
• Toenail infections: 12-16 weeks

Alternative: Itraconazole

• Continuous therapy: 200 mg daily for 12 weeks 1
• Pulse therapy: 400 mg daily for 1 week per month (2 pulses for fingernails, 3 pulses for toenails) 1

Topical Therapy:

• Ciclopirox nail lacquer has low cure rates and is not recommended as monotherapy 7

Treatment Failure Management

If treatment fails, assess for non-compliance, poor drug absorption, organism resistance, or reinfection. 3

• If clinical improvement with persistent positive mycology: Continue current therapy for additional 2-4 weeks 3
• If no clinical improvement: Switch agents (e.g., terbinafine to griseofulvin for Microsporum, or to itraconazole) 3

Critical Treatment Endpoint

The definitive endpoint is mycological cure, NOT clinical cure alone. 1, 3

• Repeat mycology sampling at end of standard treatment period 1
• Continue sampling monthly until mycological clearance is documented 1
• Clinical improvement without mycological clearance will result in relapse 4

Safety Monitoring

Monitor liver function tests with terbinafine and itraconazole, especially with pre-existing hepatic abnormalities or prolonged therapy. 1

• Itraconazole is contraindicated in heart failure 1
• Significant drug interactions with itraconazole: warfarin, certain antihistamines, antipsychotics, midazolam, digoxin, simvastatin 1

Special Considerations

Kerion Management:

• Kerion represents a delayed inflammatory host response, not bacterial infection (though secondary infection should be excluded) 2
• Do not delay systemic antifungal therapy 2
• Topical or oral corticosteroids may provide symptomatic relief for severe inflammation 2

Dermatophytid Reactions:

• Pruritic papular eruptions (especially around ear) may occur after treatment initiation 2
• These represent cell-mediated host response to dying dermatophytes 2
• Do not discontinue antifungal therapy 2
• Treat symptomatically with topical corticosteroids 2

Prevention of Recurrence

• Wear protective footwear in public bathing facilities, gyms, and hotel rooms 1
• Apply antifungal powders (miconazole, clotrimazole, tolnaftate) in shoes and on feet 1
• Avoid sharing personal items (combs, hats, pillowcases) 8

Critical Pitfalls to Avoid

• Never use topical antifungals alone for tinea capitis—they do not penetrate hair follicles 3
• Never use terbinafine for Microsporum infections—griseofulvin is superior 3
• Never stop treatment based on clinical appearance alone—mycological cure must be confirmed 1, 3
• Never forget to screen household contacts, especially with T. tonsurans infections 3
• Never assume susceptibility testing is needed—resistance development is rare 2