Nystatin: Oral

By Lauren R. Forsythe, PharmD, MBA, DICVP; Rania Gollakner, BS, DVM, MPH

What is nystatin?

Nystatin (brand names: Bio-statin®, Mycostatin®, Nadostine®, Nilstat®) is an oral antifungal used to treat fungal infections in the mouth or gastrointestinal tract, most commonly Candida.

Its use in cats, dogs, reptiles, and birds to treat fungal infections is “off label” or “extra label”. Many drugs are commonly prescribed for off-label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.

How is nystatin given?

  • Nystatin is given by mouth in the form of a tablet or oral liquid suspension. 
  • Shake the suspension well and measure carefully prior to dosing your pet.
  • It can be given with or without food, but if your pet vomits after taking this medication on an empty stomach, give the next dose with food. 

This medication should take effect within one to two days, and improvements in clinical signs should follow.

What if I miss giving my pet the medication?

If you miss a dose, give it as soon as you remember, and then continue with the regular dosing schedule. However, if it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once or give extra doses.

Are there any potential side effects?

High doses of nystatin may cause the following side effects:

  • irritation in the mouth 
  • upset stomach, such as vomiting, diarrhea, or lack of appetite

This short-acting medication should stop working within 24 hours.

Are there any risk factors for this medication?

Nystatin should NOT BE USED in patients that are allergic to it.

Nystatin should be USED WITH CAUTION in pregnant or nursing animals, as studies are limited. However, this medication is not well absorbed, so it is likely safe in these cases.

Are there any drug interactions I should be aware of?

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking. There are no known interactions with nystatin.

Is there any monitoring that needs to be done with this medication?

No specific monitoring is needed while your pet is taking this medication. Your veterinarian may monitor your pet to be sure that the medication is working.

How do I store nystatin?

  • Store at room temperature (59°F-86°F or 15°C-30°C) in a tight container.
  • Store away from light, heat, and moisture. 
  • Do not freeze the liquid suspension or expose it to temperatures above 104°F (40°C).

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.

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