Like all medicines, risperidone can cause side effects, although not everyone gets them.
Common side effects of risperidone
These common side effects of risperidone may affect up to 1 in 10 people. There are things you can do to help cope with them:
Difficulty sleeping at night
If you have trouble getting to sleep at night, try taking your medicine in the morning if you've been taking it at night. You could also try not to have a big meal, smoking or drinking alcohol, tea or coffee in the evening.
Watching television or using your mobile phone before going to bed may also stop you getting to sleep. Instead, try to relax for an hour before bedtime.
If your sleep does not get better, talk to your doctor.
If not sleeping at night makes you feel sleepy during the day, do not drive, ride a bike or use tools or machinery.
As your body gets used to risperidone, this side effect should wear off. If it does not go after a few weeks, speak to your doctor.
Headaches
Make sure you rest and drink plenty of fluids. Do not drink too much alcohol. Ask your pharmacist to recommend a painkiller.
Talk to your doctor if headaches are severe or do not go away.
Putting on weight or changes in appetite
Try to eat a healthy balanced diet without increasing your portion sizes. Do not snack on foods that contain a lot of calories, such as crisps, cakes, biscuits and sweets. If you feel hungry between meals, eat fruit and vegetables and low-calorie foods.
Regular exercise will also help to keep your weight stable.
Stomach pain
Try to rest and relax. It can help to eat and drink slowly and have smaller and more frequent meals. Putting a heat pad or covered hot water bottle on your stomach may also help.
If you are in a lot of pain, speak to your pharmacist or doctor.
Feeling or being sick (nausea or vomiting)
Stick to simple meals and do not eat rich or spicy food. It might help to take your risperidone after you've had a meal or snack.
If you're being sick, try having small, frequent sips of 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 vomiting without speaking to a pharmacist or doctor.
If you take the combined contraceptive pill or progestogen-only pill and you're being sick, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Constipation
Get more fibre into your diet, such as fresh fruit and vegetables and cereals. Try to drink several glasses of water or squash every day. Try to exercise more regularly, for example, by going for a daily walk or run. If this does not help, talk to your pharmacist or doctor.
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. Speak to a doctor if symptoms get worse or last longer than a week.
If you take the combined contraceptive pill or progestogen-only pill and you have severe, watery diarrhoea or any diarrhoea that lasts for more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Swollen breasts, pain in your breast or leaking breast milk
These can be signs of hormone changes.
Speak to your doctor if these side effects last longer than a few days. Your doctor may be able to change your medicine.
Keep taking the medicine but tell your doctor if the advice on how to cope does not help and the side effects bother you or do not go away.
Serious side effects
Serious side effects are rare and happen in less than 1 in 1,000 people.
Contact your doctor or call 111 now if:
- you get twitching or jerking movements that you cannot control in your face, tongue, or other parts of your body
- you get swelling, pain and redness in your leg – this could be a sign of a blood clot
- you have stiff muscles, find it difficult to move or control your muscles, or have shaking or drool – these are signs of dyskinesia
Immediate action required: Call 999 or go to A&E if:
- you have chest pain and difficulty breathing – these could be signs of a blood clot in your lungs
- you have weakness on one side of your face and body, trouble speaking or thinking, loss of balance or blurred eyesight – these can be signs of a stroke
- you have a high temperature, muscle stiffness, sweating, anxiety or excess saliva – these may be signs of a disorder called neuroleptic malignant syndrome
- you have a fast heartbeat
- you have difficulty breathing
- you have had a seizure or fit
- you get a painful erection (priapism) lasting more than 3 to 4 hours, or more than 1 hour if you have sickle cell disease
Do not drive to A&E. Ask someone to drive you or call 999 and ask for an ambulance.
Bring all the medicines you take with you.
Serious allergic reaction
In rare cases, risperidone may cause a serious allergic reaction (anaphylaxis).
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 risperidone. For a full list see the leaflet inside your medicines 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.