Nystatin
Nystatin is a broad-spectrum **polyene antifungal** agent, particularly noted for its efficacy against **Candida** species (especially *C. albicans*). It is not absorbed from the gastrointestinal tract, making it suitable for local/topical or gastrointestinal fungal infections. > **Clinical Pearl:** Because it is not absorbed systemically, oral formulations are only effective for GI candidiasis, while topical formulations are used for cutaneous or otic yeast infections (such as *Malassezia* otitis).
Mechanism: Nystatin binds to **ergosterol**, a major component of the fungal cell membrane. This binding → forms pores in the membrane → leads to **potassium leakage** → results in the death of the fungus.
Dosing by species
- Topical antifungal therapy · apply to affected areas · topical · q8-12h · Until clinical resolution · Often used for otitis externa or localized cutaneous candidiasis/malassezia.
- Topical antifungal therapy · apply to affected areas · topical · q8-12h · Until clinical resolution · Often used for otitis externa or localized cutaneous candidiasis/malassezia.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Known hypersensitivity to nystatin
Adverse effects
- Generally well tolerated due to lack of systemic absorption
- Rarely GI upset if given orally (nausea, vomiting, diarrhea)
- Mild irritation or hypersensitivity at the site of topical application (rare)
Monitoring
- Resolution of clinical signs of fungal/yeast infection
- Skin/ear cytology to confirm clearance of Malassezia or Candida
Overdose
Overdose is highly unlikely to cause systemic toxicity due to the lack of gastrointestinal absorption. Massive oral overdose may cause mild gastrointestinal distress (vomiting, diarrhea).
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.