Nystatin oral suspension is a liquid antifungal medication you swish around your mouth and then swallow, used to treat oral thrush (a yeast infection inside the mouth). The standard dose for adults and children is 4 to 6 mL, taken four times daily, with half the dose placed on each side of the mouth. Getting the technique right matters because this medication works through direct contact with the infected tissue.
The Swish and Swallow Technique
The key to nystatin oral suspension is maximizing contact time between the liquid and the yeast growing in your mouth. Shake the bottle well before each dose, then measure the correct amount using the dropper or measuring device that came with it. Place half the dose on one side of your mouth and the other half on the opposite side.
Once the liquid is in your mouth, swish it around thoroughly, coating your gums, tongue, the roof of your mouth, and the insides of your cheeks. Hold it in your mouth as long as you comfortably can before swallowing. There’s no strict timer here, but the longer the medication stays in contact with the affected areas, the more effective it is. Some people aim for one to two minutes of swishing, though even 30 seconds of thorough swishing is better than swallowing immediately.
After your dose, do not eat or drink anything for 30 minutes. Food and liquids wash the medication off the surfaces of your mouth too quickly, reducing how well it works.
Dosing for Adults, Children, and Infants
The suspension contains 100,000 units per mL. Adults and children take 4 to 6 mL (400,000 to 600,000 units) four times daily. Space the doses evenly throughout your waking hours.
For infants and young children, the dose is 2 mL (200,000 units) four times daily. Instead of having the baby swish the liquid, use the dropper to place 1 mL on each side of the mouth, targeting the inner cheeks where thrush patches commonly appear. Avoid feeding your infant for 5 to 10 minutes after giving the dose so the medication has time to work. For premature or low birth weight infants, a lower dose of 1 mL four times daily has been shown to be effective.
How Long to Continue Treatment
Nystatin liquid typically clears oral thrush within about a week, but you should not stop taking it the moment your symptoms disappear. Continue using it for at least 2 days after the white patches and soreness have resolved. Stopping too early can allow surviving yeast cells to regrow and cause a relapse. Your prescriber may give you a specific course length, but the general rule is: keep going for 48 hours after you feel better.
How Nystatin Works
Nystatin kills yeast by targeting a specific fat molecule called ergosterol that’s found in fungal cell membranes but not in human cells. When nystatin binds to ergosterol, it punches holes in the yeast’s outer membrane, causing the cell to leak and die. Human cell membranes use cholesterol instead of ergosterol, and nystatin interacts far less with cholesterol. This selectivity is why the medication destroys yeast without damaging the tissue in your mouth.
Because nystatin works through direct contact and is barely absorbed into your bloodstream, it only treats infections on the surface of your mouth and digestive tract. It is not effective against fungal infections elsewhere in the body.
Common and Serious Side Effects
Most people tolerate nystatin well. The side effects that do occur are usually mild and digestive in nature: nausea, diarrhea, or stomach bloating and pain. These often settle as your body adjusts.
Rarely, nystatin can cause an allergic reaction. Stop using it and seek medical attention if you develop hives, a rash, intense itching, irritation or burning in the mouth, or any difficulty breathing or swallowing. The medication is also contraindicated if you’ve had a hypersensitivity reaction to any of its ingredients in the past.
Tips for Getting the Most Out of Each Dose
- Shake before every dose. The active ingredient can settle at the bottom of the bottle, so shaking ensures each dose contains the correct concentration.
- Time doses around meals. Since you need to avoid eating or drinking for 30 minutes after each dose, taking it right after a meal (and then waiting before your next snack) is often the easiest routine.
- Use the provided measuring device. Kitchen spoons vary widely in volume. A dosing syringe or the dropper included with the bottle gives you an accurate measurement.
- Store at room temperature. Keep the bottle tightly closed and out of direct sunlight. Refrigeration is not required unless your pharmacist specifically instructs it.
Using Nystatin During Pregnancy
Formal reproductive studies have not been conducted with nystatin oral suspension, so its safety during pregnancy is not fully established. Because the medication is minimally absorbed into the bloodstream, systemic exposure is very low, but it should only be used during pregnancy when the benefit clearly justifies the use. If you’re pregnant or breastfeeding and have been prescribed nystatin, your prescriber has weighed these factors for your specific situation.