1. About dipyridamole
Dipyridamole is an antiplatelet medicine. It prevents a type of blood cell (platelets) sticking together and forming a dangerous blood clot.
Taking dipyridamole helps to prevent blood clots if you have an increased risk of having them. Your risk is higher if you have or have had:
- a stroke or "mini-stroke" (transient ischaemic attack or TIA)
- an operation on your heart to replace your heart valves
Dipyridamole is only available on prescription.
It comes as tablets and slow-release (called "modified-release") capsules. It is also available as a liquid if you find it difficult to swallow tablets or capsules.
2. Key facts
- The main side effects of dipyridamole are feeling or being sick, headaches and diarrhoea.
- You can drink alcohol with dipyridamole. However, do not drink too much while taking this medicine. It can make you dizzy or lightheaded.
- Your doctor may prescribe dipyridamole alone or with daily low-dose aspirin.
- Some medicines contain a combination of dipyridamole and low-dose aspirin (brand name Molita).
3. Who can and cannot take dipyridamole
Dipyridamole can be taken by adults aged 18 years and over to prevent strokes and after heart valve replacement surgery.
It's sometimes prescribed for children to treat a rare condition called Kawasaki disease or prevent blood clots after heart surgery.
Dipyridamole is not suitable for some people. To make sure this medicine is safe for you, tell your doctor if you:
- have ever had an allergic reaction to dipyridamole or any other medicine
- have angina or other heart problems, or have had a recent heart attack
- have a muscle weakening disease called myasthenia gravis
- have any bleeding disorders, such as haemophilia or von Willebrand disease
- have low blood pressure
- have migraines
- are trying to get pregnant, are already pregnant or breastfeeding
4. How and when to take dipyridamole
How much dipyridamole you take depends on what form you have been prescribed. Always follow your doctor's instructions.
The usual dose for slow-release capsules is 200mg, taken twice a day.
The usual dose for tablets and liquid is 300mg to 600mg, taken 3 or 4 times a day.
If the doctor prescribes it for your child, they usually need to take it 2 or 3 times a day. The doctor will use your child's weight to work out the right dose.
How to take slow-release capsules
These release the medicine slowly in your body over several hours. You will usually take 1 capsule in the morning and 1 capsule in the evening.
Take your capsules with or shortly after a meal. Swallow them whole with a drink of water. Do not crush or chew them.
Capsules are not prescribed for children.
How to take tablets or liquid
Your doctor will tell you whether to take your dose 3 or 4 times a day. Take it before meals at the same time each day. Swallow the tablet whole with a drink of water.
Dipyridamole liquid comes with a syringe or a spoon to help you or your child take the right amount. If you do not have a syringe or spoon, ask your pharmacist for one. Do not use a kitchen teaspoon because it will not give you the right amount.
What if I forget to take it?
If you forget to take dipyridamole, take it as soon as you remember, unless it's nearly time for your next dose. In this case, skip the missed dose and take the next one at the usual time.
Do not take a double dose to make up for a forgotten dose.
If you often forget doses, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to remember to take your medicines.
What if I take too much?
Taking 1 or 2 extra doses is unlikely to harm you. However, the amount of dipyridamole that can lead to overdose is different from person to person.
Urgent advice: Call 111 for advice if:
you take too much dipyridamole and you have any symptoms including:
- a faster heart rate or pain in your chest – these can be signs of a heart problem
- feeling dizzy or lightheaded, especially when you stand up or sit up quickly
- shortness of breath, wheezing and tightening of the chest
Call 111 if you're asking about a child under the age of 5 years.
If you need to go to hospital, do not drive yourself. Get someone else to drive you or call for an ambulance.
Take the dipyridamole packet or leaflet inside it plus any remaining medicine with you.
5. Side effects
Like all medicines, dipyridamole can cause side effects, although not everyone gets them.
Common side effects
These common side effects happen in more than 1 in 100 people. Talk to your doctor or pharmacist if these side effects bother you or do not go away:
- feeling sick
- diarrhoea and being sick
- feeling dizzy
- feeling hot and flushed
Serious side effects
Serious side effects are rare and happen in less than 1 in 1,000 people.
Immediate action required: Call 999 now if:
- you have pain in your chest, shortness of breath, or a fast heartbeat
Serious allergic reaction
In rare cases, dipyridamole can cause a serious allergic reaction (anaphylaxis).
Immediate action required: Call 999 or go to A&E now if:
- you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
- you're wheezing
- you get tightness in the chest or throat
- you have trouble breathing or talking
- your mouth, face, lips, tongue or throat start swelling
You could be having a serious allergic reaction and may need immediate treatment in hospital.
These are not all the side effects of dipyridamole. For a full list, see the leaflet inside your medicines packet.
You can report any suspected side effect using the Yellow Card safety scheme.
6. How to cope with side effects of dipyridamole
What to do about:
- feeling sick – try taking your tablets with or after a meal or snack. It may also help if you do not eat rich or spicy food.
- diarrhoea and being sick – drink plenty of water in small, frequent sips. Speak to a pharmacist if you have signs of dehydration, such as peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat diarrhoea or vomiting without speaking to a pharmacist or 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 the headaches are severe or last longer than a week.
- feeling dizzy – if dipyridamole makes you feel dizzy when you stand up, try getting up very slowly or stay sitting down until you feel better. If you begin to feel dizzy, lie down so that you do not faint, then sit up for a while until you feel better. Do not drive, ride a bike or use tools or machinery if you feel dizzy or a bit shaky.
- feeling hot and flushed – try cutting down on coffee, tea and alcohol. It might help to keep the room cool and use a fan. You could also spray your face with cool water or sip cold or iced drinks. The flushing should go away after a few days. If it does not, or if it's causing you problems, contact your doctor.
7. Pregnancy and breastfeeding
Dipyridamole and pregnancy
Dipyridamole is not often used in pregnancy. This is because there is little information about how the medicine may affect your baby. However, your doctor may advise you to take it if they think the benefits of taking the medicine outweigh any risks.
If you're trying to get pregnant or you are already pregnant, talk to your doctor about the benefits and possible harms of taking dipyridamole. These will depend on how many weeks pregnant you are and the reason you need to take it. There may be other medicines that are more suitable for you while you're pregnant.
Dipyridamole and breastfeeding
Only take dipyridamole while breastfeeding if your doctor advises you to.
It's not known how much dipyridamole gets into breast milk, but it's likely to be a small amount.
If your doctor says it is OK for you to keep taking dipyridamole, then monitor your baby for any possible side effects, such as bruises or bleeding easily. However, it's unlikely that dipyridamole will cause any side effects in your baby.
Talk to your doctor, midwife, or health visitor if you have any concerns about your baby while you are breastfeeding.
Non-urgent advice: Tell your doctor if you're:
- trying to get pregnant
8. Cautions with other medicines
Some medicines can affect the way dipyridamole works.
Tell your doctor if you're taking these medicines before you start taking dipyridamole:
- other medicines to prevent blood clots, such as low-dose aspirin, clopidogrel, ticagrelor, warfarin, dabigatran, apixaban or rivaroxaban
- medicines for high blood pressure, such as bisoprolol, ramipril or furosemide
- indigestion medicines, such as ranitidine, proton pump inhibitors like omeprazole, or antacids that contain magnesium or aluminium
- digoxin for heart problems
- medicines used to treat myasthenia gravis
Taking dipyridamole with everyday painkillers
You can take paracetamol together with dipyridamole if you need a painkiller.
To prevent blood clots, your doctor may prescribe daily low-dose aspirin (75mg tablets) to take together with dipyridamole.
Taking dipyridamole with indigestion medicines
Some indigestion medicines, such as omeprazole, may reduce the effect of dipyridamole. This is important if you're taking dipyridamole as tablets or liquid, but it's not a problem if you're taking capsules.
If you need to take indigestion medicines, do not take them at the same time of day as dipyridamole tablets or liquid. Take them 2 to 3 hours before or after your dose of dipyridamole.
Mixing dipyridamole with herbal remedies and supplements
There might be a problem with taking some herbal remedies and supplements with dipyridamole, especially ones that can affect your blood, such as ginkgo.
Important: Medicine safety
Tell your doctor or pharmacist if you're taking any other medicines, including herbal medicines, vitamins or supplements.
9. Common questions about dipyridamole
How does dipyridamole work?
Dipyridamole slows the blood's clotting action by making platelets less sticky.
Platelets are blood cells that stick together and block cuts and breaks in blood vessels.
However, in people at risk of heart attack or stroke, platelets can stick together inside already narrowed blood vessels to form a clot. The clot can stop blood flowing to the heart or brain and cause a heart attack or stroke.
If you take it every day, dipyridamole stops platelets from clumping together to form unwanted blood clots. This helps to prevent heart attacks and strokes.
How long does it take to work?
Dipyridamole works within 2 hours of taking it.
When will I feel better?
You may not feel any different after you start taking dipyridamole. However, this does not mean the medicine is not working.
Carry on taking dipyridamole even if you feel well, as you'll still be getting the benefits.
How long will I take it for?
You will usually need to take dipyridamole for the rest of your life.
Is it safe to take it for a long time?
Dipyridamole is generally safe to take for a long time. In fact, it works best if you take it for many months or years.
What will happen if I stop taking it?
Do not stop taking dipyridamole without talking to your doctor.
If you stop taking dipyridamole, your blood will go back to clotting at the rate it did before, usually within 2 days of stopping the medicine. This means you may be at increased risk of serious problems like heart attacks or strokes.
Are there any other similar medicines?
Not all medicines that prevent blood clots are suitable for everyone. Talk to your doctor or pharmacist to find out why you've been recommended a particular medicine.
Can I drink alcohol with it?
Yes, you can drink alcohol while taking dipyridamole as long as you stick to the national alcohol guidelines of no more than 14 units a week for men and women. A standard glass of wine (175ml) is 2 units. A pint of lager or beer is usually 2 to 3 units.
Both alcohol and dipyridamole can reduce your blood pressure. Together, they can make you feel dizzy or lightheaded. If you find dipyridamole makes you feel dizzy, it's best to stop drinking alcohol.
Is there any food or drink I need to avoid?
Apart from limiting your alcohol intake, you can eat and drink normally while taking dipyridamole.
Will I need to stop dipyridamole before surgery?
Because of the risk of bleeding, you may need to stop taking dipyridamole a few days before you have an operation. Tell the surgeon in advance that you are taking dipyridamole.
Can I have vaccinations?
Yes, you can have vaccinations while taking dipyridamole.
Will it affect my contraception or fertility?
If dipyridamole makes you vomit, your contraceptive pills may not protect you from pregnancy. Look on the pill packet to find out what to do.
Taking dipyridamole does not have any effect on male or female fertility.
Will it affect my sex life?
Dipyridamole will not affect your sex life.
Can I drive or ride a bike?
Most people can drive or ride a bike while taking dipyridamole. However, if dipyridamole makes you feel dizzy, do not drive, ride a bike or operate tools or machinery until the dizziness is gone.
Can lifestyle changes help improve my general health?
If you've been prescribed dipyridamole, you can also improve your health by making some key lifestyle changes.
- Quit smoking – smoking increases your heart rate and blood pressure. Quitting smoking brings down your risk of heart attack or stroke. Try to avoid secondhand smoke too.
- Cut down on alcohol – it's a good idea not to drink more than 14 units of alcohol a week.
- Get more exercise – regular exercise keeps your heart and blood vessels in good condition. It does not need to be too energetic – walking every day can help.
- Eat well – aim to eat a diet that includes plenty of fruit and veg, wholegrains, fat-free or low-fat dairy products, and lean protein. It's a good idea to follow these tips for a lower salt diet too. Aim for no more than 6g of salt a day.
- Manage stress – when you're anxious or upset, your heart beats faster, you breathe more heavily and your blood pressure often goes up. This raises your risk of heart attack and stroke. Find ways to reduce stress in your life. To give your heart a rest, try napping or putting your feet up when possible. Spend time with friends and family to be social and help keep stress at bay.
- Vaccinations – if you have heart disease, it's recommended you have a flu vaccine every year and a pneumococcal vaccine every 5 years. Ask your doctor about these vaccinations. You can have them free on the NHS.