Nystatin

Nystatin is a polyene antifungal used for local treatment of susceptible yeast infections. Poor gastrointestinal absorption makes oral preparations useful primarily at mucosal and luminal sites. Veterinary applications include oral or crop candidiasis in birds and selected oral, gastrointestinal, cutaneous or otic infections in other species.

Group

Polyene antifungal

Mechanism of Action

Nystatin binds fungal membrane sterols, particularly ergosterol, and forms structures that increase membrane permeability. Leakage of potassium and other intracellular constituents impairs fungal cell function and survival. The local effect requires contact with susceptible organisms. Minimal absorption after oral administration concentrates activity in the mouth and gastrointestinal lumen.

Dose Rates

Birds

Use / stage	Dose	Route	Schedule	Instructions
Crop or gastrointestinal candidiasis	300000–600000 IU/kg	PO	Every 12 h	Oral suspension 100,000 units/mL; local contact is essential.
Alternative candidiasis contact schedule	Reference only	PO		A narrative describes 300,000 IU/kg and recommends administration three times daily before feeding for local contact, while also describing twice-daily use. Resolve the intended schedule for the case; not an automatic merged regimen.
Alternative enteric candidiasis regimen	200000–300000 IU/kg	PO	Every 8–12 h	Ensure contact with oral lesions; tubing directly into the crop may bypass them.
Post-antibiotic candidiasis	333333.3333333334 IU/kg	PO	Every 8–24 h	Up to 14 days; Equivalent to 1 mL of 100,000 units/mL suspension per 300 g, one to three times daily for 7–14 days. Do not gavage when mouth lesions require contact.
Neonatal antifungal combination during antibiotics	Reference only	PO	Every 12 h	A described mixture combines a 100 mg fluconazole tablet with 20 mL nystatin 100,000 units/mL and gives 0.5 mL/kg twice daily during antibiotic treatment. Final compounded volume/stability is not established, so no component concentration is invented.

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Oral or gastrointestinal candidiasis	100000 IU/animal	PO	Every 6 h	Local action requires contact with infected tissue; oral suspension is not systemic antifungal treatment.
Alternative oral candidiasis regimen	50000–150000 IU/animal	PO	Every 8 h

Cats

Use / stage	Dose	Route	Schedule	Instructions
Oral or gastrointestinal candidiasis	100000 IU/animal	PO	Every 6 h	Local action requires contact with infected tissue; oral suspension is not systemic antifungal treatment.

Ratites

Use / stage	Dose	Route	Schedule	Instructions
Enteric candidiasis	250000–500000 IU/kg	PO	Every 12 h

Turtles

Use / stage	Dose	Route	Schedule	Instructions
Enteric yeast infection	100000 IU/kg	PO	Every 24 h	Up to 10 days

Reptiles

Use / stage	Dose	Route	Schedule	Instructions
Enteric yeast infection	100000 IU/kg	PO	Every 24 h	General reptile listing; species-specific assessment remains necessary.

Indications

Treatment of oral, crop or gastrointestinal candidiasis in birds.
Local treatment of susceptible oral or gastrointestinal Candida infections in dogs, cats or selected other veterinary species.
Treatment of selected cutaneous or otic yeast infections using an appropriate nystatin-containing topical preparation.

Contraindications

Hypersensitivity
Parenteral use of oral or topical formulations

Adverse effects

Gastrointestinal intolerance
Poor acceptance of oral suspension
Local irritation

Toxicity

Oral systemic toxicity is generally limited by poor absorption; assess excipients and route errors.

Preparations

Preparation	Form	Strength	Route
Nystatin oral suspension 100,000 units/mL Shake well. Intended for local oral/GI exposure, not systemic or injectable treatment.	Oral Liquid	100000 IU / mL	PO
Nystatin oral tablets 500,000 units	Tablet	500000 IU / tablet	PO
Nystatin topical powder 100,000 units/g	Powder	100000 IU / g	TOPICAL
Nystatin topical ointment 100,000 units/g	Other	100000 IU / g	TOPICAL
Panalog nystatin combination ointment All active strengths per gram as listed. Combination treatment; do not opt into single-component dose conversion. Skin use requires a lesion-specific plan.	Other	nystatin 100000 IU / g + triamcinolone acetonide 1 mg / g + neomycin sulfate 2.5 mg / g + thiostrepton 2500 IU / g	TOPICAL

Monitoring and Administration

Shake suspension and bring it into direct contact with infected tissue. Diagnose and correct underlying husbandry or immunosuppressive factors in birds.

The avian table lists twice-daily dosing; another narrative recommends before-feed contact three times daily. These are retained separately rather than merged into an artificial interval range.

An additional oral canine total of 22,000 units/kg/day is listed without a division schedule; it is not automatically converted into a per-administration amount.

Poultry feed treatment was described using Mycostatin-20 at 50 or 100 g product per ton for 7–10 days; product potency is required before converting to active units.

Store oral tablets and suspension tightly closed and protected from light at 15–30°C; avoid freezing the suspension or heat above 40°C.

Topical nystatin-steroid combinations may suit focal yeast lesions; use short courses and reduce frequency once controlled. Avoid eyes; neomycin may cause contact sensitization and glucocorticoids may cause skin atrophy or HPA suppression.

Historical intrauterine infusion: 250,000–1,000,000 IU in sterile water, often daily or every other day for 3–7 days. Saline causes precipitation. Evidence for dose, volume and frequency is limited; the schema lacks an intrauterine route.