4 Nystatin Side Effects You Should Know About
Key takeaways:
Nystatin (Nystop, Nyamyc) is a medication that treats fungal yeast infections of the skin, mouth, and gut. It’s generally well tolerated with few side effects for most people.
Oral nystatin side effects can include mouth irritation, upset stomach, and diarrhea. Topical nystatin can cause skin discomfort, such as burning or itching, where it’s applied.
In very rare cases, nystatin can cause a severe skin rash or an allergic reaction. Seek emergency care if these occur.
Table of contents
If you’re dealing with a fungal infection, your healthcare team may prescribe nystatin. It’s an antifungal medication that comes in both oral and topical forms (Nystop, Nyamyc). Nystatin treats yeast infections of the skin, mouth (thrush), and gut. It’s also a common ingredient in magic mouthwash, a compounded medication that treats mouth sores.
Nystatin is well tolerated by most people because it isn’t absorbed into your bloodstream. Instead, it works locally on the skin, mouth, or lining of your gut (depending on what form you’re using). As a result, it typically causes fewer side effects than other oral antifungal medications. But there are still some possible nystatin side effects, so it’s good to be aware of them.
Nystatin side effects at a glance
Nystatin side effects can vary depending on whether you’re using an oral or a topical form. Oral forms of nystatin include a liquid (suspension) and tablets. Topical forms include nystatin cream, ointment, and powder.
Possible oral nystatin side effects include:
Mouth irritation
Upset stomach
Nausea and vomiting
Diarrhea
Decreased appetite
Dry mouth
Rash (rare)
Severe skin reactions (rare)
Fast heart rate (rare)
Muscle pain (rare)
Possible topical nystatin side effects include:
Burning or pain where applied
Itching
Rash
Below, we’ll cover four nystatin side effects in more detail and what you can do about them.
1. Mouth or skin irritation
Most people tolerate nystatin well, with no issues. But sometimes, nystatin can irritate the area where it’s applied. So oral nystatin, especially the liquid, can irritate your mouth. And topical nystatin may irritate your skin. This irritation may lead to redness as well as a burning or stinging sensation.
Keep in mind that nystatin treats fungal skin infections, which can also irritate your skin and mouth. So it may be hard to tell if it’s the medication or the infection it’s treating that’s causing your symptoms.
Oral thrush 101: Learn how to tell if you or your child has oral thrush and what medications are available to treat it.
Oral antifungals: Read up on the different oral antifungal medications and how they differ.
Nystatin vs. clotrimazole: Here’s how these two topical antifungal treatments compare.
If the pain or irritation is severe when using nystatin, let your prescriber know. They can help determine if the medication is to blame.
In rare cases, oral nystatin may cause a severe skin reaction called Stevens-Johnson syndrome. This causes your skin to blister and peel. In most cases it also causes flu-like symptoms, such as a fever and muscle aches. If any of these symptoms appear while taking nystatin, seek emergency care. This condition can be dangerous without proper treatment.
2. Upset stomach
Oral nystatin can upset your stomach, causing side effects such as nausea, lack of appetite, and bloating.
Taking nystatin tablets with food may help reduce stomach-related side effects. But if you’re swishing with nystatin liquid and/or holding it in your mouth, you should wait at least 30 minutes before eating or drinking. This helps give the medication time to work.
Nystatin liquid may taste bitter or unpleasant to some people, which could contribute to nausea. If you find the taste bothersome, ask your pharmacist if they can change the flavor. Many pharmacies offer this service for a small fee. You can also try eating something cold, such as an ice pop or ice cream, before your nystatin dose. This can help numb your taste buds to avoid the taste.
If you have stomach-related symptoms that are severe or worsening while taking nystatin, be sure to let your prescriber know.
3. Diarrhea
Diarrhea is a possible side effect of oral nystatin. Usually, diarrhea from nystatin is mild and goes away on its own. In the meantime, stay hydrated and avoid foods that may worsen diarrhea, such as fried or spicy items.
Keep in mind that fungal infections in the gut can also cause diarrhea. In this case, it may improve as nystatin starts working. But contact your prescriber if you have persistent, severe, or bloody diarrhea during nystatin treatment. They can determine the cause and advise you on the next steps to take.
4. Trouble breathing or swallowing
Like any medication, nystatin may cause allergic reactions in some people. Symptoms of a severe allergic reaction may include trouble breathing or swallowing. You may also develop a raised rash (hives) or swelling of your mouth and tongue. If you develop any signs of an allergic reaction, seek emergency care right away.
Frequently asked questions
Fatigue isn’t a reported nystatin side effect. But nystatin treats fungal infections. And it’s common to feel more tired or have less energy than usual when you’re fighting an infection. This is the body’s way of getting the rest it needs. Your energy levels should return to their usual level once your infection is treated. But let your prescriber know if fatigue worsens or doesn’t improve.
No, nystatin isn’t hard on your liver. In fact, when you take nystatin by mouth, it mainly works in your mouth and digestive tract as it moves through your body. Very little nystatin is absorbed into your bloodstream, so it has little to no effect on other parts of your body.
The bottom line
Nystatin is an antifungal medication available in oral and topical (Nystop, Nyamyc) forms. It treats fungal yeast infections of the skin, mouth (thrush), and gut. Nystatin works locally where it’s applied and isn’t absorbed into your bloodstream. So it’s generally very well tolerated with few side effects.
Possible oral nystatin side effects include mouth irritation as well as nausea, upset stomach, and diarrhea. Topical nystatin products may cause mild skin discomfort, such as itching or burning where applied.
If pain or irritation of the mouth or skin is severe after using nystatin, ask your prescriber for guidance. In very rare cases, nystatin may cause a severe skin reaction or an allergic reaction. Seek emergency care if these occur.
Why trust our experts?
References
Atlantic Biologicals. (2025). Nystatin- nystatin suspension [package insert].
Bryant Ranch Prepack. (2025). Nystatin- nystatin cream [package insert].
Bryant Ranch Prepack. (2025). Nystatin- nystatin ointment [package insert].
Bryant Ranch Prepack. (2025). Nystop- nystatin powder [package insert].
Centers for Disease Control and Prevention. (2024). Symptoms of candidiasis.
Chartwell Rx. (2024). Nystatin- nystatin tablet, film coated [package insert].
Lamps, L. W., et al. (2014). Fungal infections of the gastrointestinal tract in the immunocompromised host-an update. Advances in Anatomic Pathology.
LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. (2020). Nystatin. National Institute of Diabetes and Digestive and Kidney Diseases.
MedlinePlus. (2018). Nystatin.
National Health Service. (2023). How and when to take or use nystatin.
News in Health. (2024). The fungus among us. National Institutes of Health.
Rai, A., et al. (2022). Nystatin effectiveness in oral candidiasis treatment: A systematic review & meta-analysis of clinical trials. Life.
Was this page helpful?
Related Articles
Browse medications
View AllResearch prescriptions and over-the-counter medications from A to Z, compare drug prices, and start saving.