Like all medicines, nystatin can cause side effects, but most people have no side effects or only minor ones.
Common side effects
If you're taking nystatin liquid, there are things you can do to help with these side effects:
Diarrhoea
Drink lots of fluids, such as water or squash, to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee.
Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.
If you take the combined pill or progestogen-only pill and you have severe diarrhoea for more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Feeling or being sick (nausea or vomiting)
Stick to simple meals and do not eat rich or spicy food. Make sure you take nystatin liquid after a meal or snack.
If you're being sick, try small, frequent sips of water to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee.
If you take the combined pill or progestogen-only pill and you're being sick, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Talk to your pharmacist or doctor if the advice on how to cope does not help and these side effects bother you or do not go away.
If you're using nystatin cream or ointment, stop using the product and talk to your pharmacist or doctor if:
- you have a rash or itchy, dry or swollen skin where you've applied it
- you get a new infection
Your pharmacist or doctor may be able to recommend a different medicine.
Serious allergic reaction
It happens rarely but it's possible to have a serious allergic reaction (anaphylaxis) to nystatin.
Immediate action required: Call 999 now if:
- your lips, mouth, throat or tongue suddenly become swollen
- you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
- your throat feels tight or you're struggling to swallow
- your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
- you suddenly become very confused, drowsy or dizzy
- someone faints and cannot be woken up
- a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)
You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.
These can be signs of a serious allergic reaction and may need immediate treatment in hospital.
Do not drive yourself to A&E.
The person you speak to at 999 will give you advice about what to do.
Other side effects
These are not all the side effects of nystatin. For a full list, see the leaflet inside your medicine packet.
Reporting side effects
You can report any suspected side effect using the Yellow Card safety scheme.
Visit the Yellow Card website for more information about reporting side effects.