Prescription ·Strong evidence ·Reviewed May 2026
Nystatin is a polyene antifungal antibiotic used to treat candidiasis (Candida infections) of the mouth, throat, and gastrointestinal tract, as well as cutaneous and vaginal candidal infections. When taken orally as a suspension or tablet it is essentially not absorbed from the gut, so it acts locally on fungi in contact with the mucosa rather than systemically. It is not effective against systemic or invasive fungal infections.
The bottom line
Evidence rating strong. Most-documented uses: oropharyngeal candidiasis (oral thrush), intestinal candidiasis, cutaneous and mucocutaneous candidal infections. 2 sources indexed (2010–2020), with 3 interaction records on file.
Core mechanism
Nystatin binds preferentially to ergosterol, the principal sterol in the fungal cell membrane. This binding forms transmembrane pores or channels that disrupt membrane integrity, causing leakage of potassium and other intracellular components and ultimately fungal cell death. Because mammalian cell membranes contain cholesterol rather than ergosterol, nystatin is relatively selective for fungi; its low systemic absorption from oral and topical routes further limits host toxicity.2,1
Negligibly absorbed from the intact gastrointestinal tract; it acts topically on mucosal surfaces. For oral suspension, retain the dose in the mouth as long as possible before swallowing, and avoid eating or drinking immediately afterward to maximize mucosal contact time.
Oral nystatin can reduce viability of yeast-containing probiotics such as Saccharomyces boulardii when taken together.
Recommendation: Separate yeast probiotics from oral nystatin; bacterial probiotics are less likely to be directly affected.
Psyllium can delay or reduce absorption of some oral drugs if taken at the same time as Nystatin.
Recommendation: Separate psyllium from Nystatin by at least 2 hours unless the prescriber gives different timing instructions.
Nystatin oral suspension is frequently dosed to coat the oral mucosa, and patients are advised to avoid food and drink shortly after dosing so the drug stays in contact with affected tissue. Oral iron supplements are gastric irritants often taken with food and acidic juices, and dosing them at the same time can wash nystatin off mucosal surfaces and prompt eating or drinking that shortens contact time. There is no systemic pharmacokinetic interaction because nystatin is not absorbed.
Recommendation: Take oral iron at a separate time from nystatin oral suspension, ideally separated by at least 1 to 2 hours, so the antifungal can maintain contact with the mouth and throat. After a nystatin swish-and-swallow dose, wait the directed period (about 20 to 30 minutes) before consuming iron, food, or beverages.
Numbered references. Citations throughout the page link here.
Topical and oral antifungals including nystatin are effective for treating and preventing oral candidiasis, though azoles may show higher efficacy in some immunocompromised populations.
Oral nystatin is not absorbed from intact gastrointestinal mucosa and exerts antifungal activity by binding sterols (chiefly ergosterol) in the fungal cell membrane.
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