Is Amphotericin B effective against tinea corporis?

Amphotericin B is NOT Effective Against Tinea Corporis

Amphotericin B should not be used to treat tinea corporis (ringworm of the body), as it has no activity against dermatophytes, the causative organisms of this superficial fungal infection. 1

Why Amphotericin B is Inappropriate

Amphotericin B is a polyene antifungal that targets systemic fungal infections caused by yeasts (Candida, Cryptococcus) and endemic fungi (Histoplasma, Blastomyces, Coccidioides), as well as molds like Aspergillus and Mucor. 2 The drug is specifically indicated for invasive candidiasis, cryptococcosis, aspergillosis, and mucormycosis—all life-threatening systemic infections. 1

Tinea corporis is a superficial dermatophyte infection affecting only the outermost layers of skin, caused by organisms like Trichophyton, Microsporum, and Epidermophyton species. 3 These dermatophytes are fundamentally different from the deep fungal pathogens that amphotericin B targets. 1

Correct Treatment for Tinea Corporis

First-Line Topical Therapy

• Clotrimazole 1% cream applied twice daily for 2-4 weeks is highly effective for tinea corporis. 4
• Miconazole 2% cream applied twice daily for 2-4 weeks is another effective topical option. 4
• Terbinafine cream demonstrates superior efficacy compared to placebo, with a number needed to treat of 3. 3

Oral Therapy for Extensive Disease

• Oral fluconazole 150-200 mg weekly for 2-4 weeks should be considered for extensive or treatment-resistant cases. 4
• Itraconazole 100 mg daily for 15 days achieves an 80% clinical response rate in tinea corporis, with sustained improvement at 6 weeks post-treatment. 5
• Oral terbinafine is effective for widespread dermatophyte infections and has minimal drug interaction potential, making it suitable for immunocompromised patients. 6

Critical Clinical Pitfalls

Never use amphotericin B for superficial dermatophyte infections. 1 The drug's toxicity profile—including nephrotoxicity in up to 50% of recipients and significant infusion-related reactions—makes it completely inappropriate for a benign, self-limited condition like tinea corporis. 2 Amphotericin B deoxycholate requires intravenous administration at doses of 0.5-1.0 mg/kg daily, with lipid formulations requiring 3-5 mg/kg daily. 2 This level of intervention is reserved exclusively for life-threatening systemic fungal infections. 2

If topical therapy fails after 2 weeks, switch to a different antifungal class or escalate to oral therapy—never consider amphotericin B. 4