Dipyridamole belongs to the class of medications called platelet aggregation inhibitors or antiplatelets. It is used to prevent blood clots that may occur after a heart valve replacement. It works by preventing certain types of blood cells, called platelets, from sticking together. It is also used for certain types of tests for the heart that examine how well blood is flowing through the heart.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended oral adult dose of dipyridamole for preventing blood clots is 100 mg 4 times daily one hour before meals. If taken with 1,000 mg of ASA daily, the dose of dipyridamole can be reduced to 25 mg 4 times daily.

When used for medical tests that examine how well blood is flowing through the heart, dipyridamole is given by injection in a hospital.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not take dipyridamole if you are allergic to dipyridamole or any ingredients of the medication.

Do not give the injectable form of this medication to anyone who is in a state of shock or collapse.

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• abdominal or stomach cramps
• diarrhea
• dizziness or lightheadedness
• flushing
• headache
• nausea or vomiting
• rash
• weakness

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• chest pain
• gallstones
• increased heart rate
• low blood pressure (symptoms may include dizziness or fainting)
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• skin rash

Stop taking the medication and seek immediate medical attention if any of the following occur:

• chest pain
• signs of bleeding in the stomach (e.g., bloody, black, or tarry stools; spitting up of blood; vomiting blood or material that looks like coffee grounds)
• symptoms of a serious allergic reaction (such as hives, difficulty breathing, or swelling of the face or throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Liver function: Liver disease or reduced liver function may cause this medication to build up in the body, causing side effects. If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Your doctor may want to test your liver function regularly with blood tests while you are taking this medication.

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Low blood pressure: Dipyridamole may cause lowering of blood pressure and increase the effect of blood pressure-lowering medications.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking dipyridamole, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

There may be an interaction between dipyridamole and any of the following:

• acetylsalicylic acid (ASA)
• aliskiren
• alpha-agonists (e.g., clonidine, methyldopa)
• alpha-blockers (e.g., alfuzosin, doxazosin, tamsulosin)
• amiodarone
• apixaban
• beta-adrenergic blockers (e.g., atenolol, propranolol, sotalol)
• calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
• carvedilol
• cholinesterase inhibitors (e.g., donepezil, galantamine, rivastigmine)
• cladribine
• clopidogrel
• colchicine
• dabigatran
• glucosamine
• heparin
• herbal products that affect blood clotting (e.g., cat's claw, chamomile, fenugreek, evening primrose, feverfew, garlic, ginger, ginseng, gingko biloba, turmeric)
• low molecular weight heparins (e.g., dalteparin, enoxaparin, tinzaparin)
• multivitamin/mineral supplements
• non-steroidal anti-inflammatory medications (NSAIDs; e.g., diclofenac, ibuprofen, naproxen)
• obinutuzumab
• omega-3 fatty acids
• pentoxifylline
• prasugrel
• protein kinase inhibitors (e.g., acalabrutinib, crizotinib, dasatinib)
• riociguat
• rivaroxaban
• selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, fluoxetine, paroxetine, sertraline)
• serotonin-norepinephrine reuptake inhibitors (SNRIs; desvenlafaxine, duloxetine, venlafaxine)
• ticagrelor
• vitamin E
• vortioxetine
• warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.