Mycostatin (Nystatin)

Nystatin is used to treat fungal infections of the gastrointestinal and upper digestive tract caused by Candida species.

• Candidiasis of the gastrointestinal tract: eradicates Candida overgrowth and relieves abdominal discomfort.
• Oral thrush (oropharyngeal candidiasis): clears yeast plaques from the mouth and throat, improving swallowing and taste.
• Esophageal candidiasis: reduces fungal burden in the esophagus, alleviating pain and dysphagia.
• Prevention of Candida colonisation in patients receiving broad‑spectrum antibiotics: helps maintain normal flora.

• Nystatin binds selectively to ergosterol, an essential sterol component of fungal cell membranes. This interaction creates pores that increase membrane permeability, leading to leakage of intracellular electrolytes and macromolecules, ultimately causing fungal cell death. Because human cell membranes contain cholesterol rather than ergosterol, nystatin exhibits selective toxicity toward Candida species with minimal systemic absorption when administered orally. Thus, oral nystatin acts locally within the gastrointestinal lumen and oral cavity.

Nystatin may cause adverse reactions, most of which are mild and limited to the gastrointestinal tract or oral cavity.

Common Side Effects

• Nausea: mild stomach upset after ingestion.
• Diarrhea: loose stools during treatment.
• Oral irritation: burning or soreness in the mouth.
• Vomiting: occasional expulsion of stomach contents.

Serious or Rare Side Effects

• Allergic reaction: rash, itching, or swelling indicating hypersensitivity.
• Severe gastrointestinal upset: persistent vomiting or bloody diarrhea.
• Anaphylaxis: life‑threatening systemic allergic response.
• Kidney impairment: uncommon renal function changes.

When prescribing oral nystatin, several precautions should be observed to ensure safety and effectiveness.

• Assess patient history: confirm Candida infection and rule out hypersensitivity to polyene antifungals.
• Evaluate renal function: adjust use in patients with severe kidney disease.
• Monitor for drug interactions: avoid concomitant use with nephrotoxic agents without supervision.
• Use appropriate duration: limit therapy to the prescribed course to prevent resistance.
• Pregnancy and lactation: consider risks and benefits, as safety data are limited.
• Store at ambient temperature: keep below 25 °C in the original container, protected from moisture.

Nystatin may interact with other medicines, affecting its efficacy or safety.

Major Interactions (Avoid)

• Concurrent use with nephrotoxic antibiotics (e.g., amphotericin B): may increase renal toxicity.
• Combination with systemic antifungals that share the same target: can lead to additive toxicity.

Moderate Interactions (Monitor Closely)

• Antacids containing magnesium or aluminum: may reduce oral absorption of nystatin.
• Broad‑spectrum antibiotics: may alter gut flora, affecting nystatin’s local activity.
• Immunosuppressants (e.g., cyclosporine): monitor renal function when both are used.