What is the recommended dose of nystatin (antifungal medication) for treating fungal infections?

Nystatin Dosing for Fungal Infections

For oropharyngeal candidiasis (oral thrush), nystatin suspension should be dosed at 400,000-600,000 units (4-6 mL) four times daily for 7-14 days in adults and children, with the medication swished in the mouth as long as possible before swallowing. 1, 2

Dosing by Age Group

Infants

• Standard dose: 200,000 units (2 mL) four times daily 2
• Premature/low birth weight infants: 100,000 units (1 mL) four times daily 2
• Administration technique: Use dropper to place one-half of dose in each side of mouth and avoid feeding for 5-10 minutes 2

Children and Adults

• Standard dose: 400,000-600,000 units (4-6 mL) four times daily 1, 2
• Alternative formulation: 1-2 nystatin pastilles (200,000 units each) four times daily 1
• Administration: Place one-half of dose in each side of mouth, retain as long as possible before swallowing 2

Treatment Duration and Monitoring

• Standard duration: 7-14 days for uncomplicated oropharyngeal candidiasis 3, 1
• Pediatric duration: 1-7 days may be sufficient in children with uncomplicated disease 3
• Continue treatment: For at least 48 hours after symptoms disappear and cultures confirm eradication of Candida albicans 1, 2

Critical Clinical Caveats

When Nystatin is NOT Appropriate

Nystatin should NOT be used as first-line therapy for moderate-to-severe oral candidiasis or in immunocompromised patients, as it has significantly lower efficacy compared to systemic azoles. 1

• Nystatin has clinical cure rates of only 32-54% compared to 100% with fluconazole in infants 1
• For moderate-to-severe disease, oral fluconazole 100-200 mg daily for 7-14 days is superior and should be used instead 1
• Nystatin is inadequate for esophageal candidiasis, which requires systemic therapy 1

Optimal Formulation Selection

• Nystatin pastilles alone or in combination with suspension are more effective than suspension alone 4
• Higher dose pastilles (400,000 IU) achieve better mycological cure rates than 200,000 IU 4
• Treatment duration of 4 weeks may be more effective than 2 weeks for persistent infections 4

Treatment Algorithm by Disease Severity

Mild Oral Thrush

1. First-line: Nystatin suspension 400,000-600,000 units four times daily for 7-14 days 1
2. Alternative topical agents: Clotrimazole troches (10 mg 5 times daily) or miconazole buccal tablets (50 mg once daily) offer superior convenience 1

Moderate-to-Severe Oral Thrush

1. First-line: Oral fluconazole 100-200 mg daily for 7-14 days 1
2. Do NOT use nystatin as it has suboptimal efficacy 1

Refractory Disease (Fluconazole Failure)

1. Itraconazole solution 200 mg once daily 1
2. Posaconazole suspension 400 mg twice daily for 3 days, then 400 mg daily 1
3. Voriconazole 200 mg twice daily 1
4. Intravenous amphotericin B 0.3 mg/kg daily as last resort 1

Special Populations and Adjunctive Measures

Denture-Related Candidiasis

• Denture disinfection must accompany antifungal therapy for successful treatment 1

HIV-Infected Patients

• Antiretroviral therapy is more important than antifungal choice for reducing recurrence 1
• For recurrent infections, fluconazole 100 mg three times weekly for chronic suppression 1

Adverse Effects

• Most common: Poor taste and gastrointestinal reactions 4
• Generally well-tolerated with minimal systemic absorption 2

Common Pitfalls to Avoid

1. Using nystatin for moderate-severe disease: This leads to treatment failure and prolonged infection 1
2. Inadequate contact time: Patients must swish medication thoroughly for at least 2 minutes before swallowing 1
3. Premature discontinuation: Continue for full 48 hours after symptom resolution 1, 2
4. Ignoring dentures: Failure to disinfect dentures leads to reinfection 1
5. Using nystatin for esophageal candidiasis: Systemic therapy is required 1