Side Effects of Nystatin
Nystatin is generally well-tolerated even with prolonged therapy, with oral irritation, sensitization, and gastrointestinal upset being the most common side effects 1.
Common Side Effects
Gastrointestinal Effects
- Diarrhea (including rare cases of bloody diarrhea)
- Nausea
- Vomiting
- General gastrointestinal upset/disturbances 1
These gastrointestinal effects are particularly relevant since nystatin works through direct contact with mucous membranes and is minimally absorbed systemically 2. Oral doses exceeding five million units daily have been associated with increased gastrointestinal upset 1.
Local Reactions
- Oral irritation
- Sensitization 1
Rare Side Effects
Dermatologic
- Rash
- Urticaria (rare)
- Stevens-Johnson syndrome (very rare) 1
Other Rare Reactions
- Tachycardia
- Bronchospasm
- Facial swelling
- Nonspecific myalgia 1
Administration Considerations
When administering nystatin suspension for oral candidiasis, proper technique is essential:
- Patients should swish the suspension thoroughly around the mouth for at least 2 minutes before swallowing or spitting out
- Use after meals
- Avoid eating/drinking for 30 minutes after administration 2
Poor adherence to these administration protocols may reduce effectiveness and potentially increase local irritation.
Practical Considerations
Patient Tolerability
In comparative studies, patients reported more inconvenience with nystatin compared to systemic antifungals like fluconazole. In one study, 50% of patients in the nystatin group reported inconvenience from taking the medication compared with only 23% in the fluconazole group 3.
Treatment Efficacy vs. Side Effects
While nystatin is effective for treating oral candidiasis (80% clinical improvement rate in one study), it may require longer treatment duration (21 days) compared to alternatives like fluconazole (7 days) 3, potentially increasing the duration of side effect exposure.
Special Populations
Neonates and Infants
Nystatin is commonly used in neonates for prevention of invasive candidiasis at a dosage of 100,000 IU every 8 hours 4. While generally well-tolerated, there are potential concerns about gut damage and necrotizing enterocolitis in this vulnerable population 4.
Immunocompromised Patients
For HIV-infected patients and other immunocompromised individuals, nystatin remains an option for treating oropharyngeal candidiasis, though fluconazole is often preferred due to better tolerability and efficacy 4.
Clinical Management of Side Effects
If gastrointestinal side effects occur, consider:
- Adjusting the timing of administration (after meals)
- Ensuring proper administration technique
- Evaluating for alternative antifungal options if side effects are significant
For patients experiencing significant side effects or treatment failure with nystatin, alternative antifungal agents such as fluconazole may be more appropriate, particularly for systemic or resistant infections 4.