context: Antiplatelet drugs are a group of powerful medicines that prevent blood clots. When you are wounded, platelets arrive on the scene and group together to form a clot that stops the bleeding. This is a good thing when an injury involves a break in your skin. But platelets can also group when injury to a blood vessel comes from the inside, as may happen in an artery affected by atherosclerosis. In this situation, the platelets cause blood clots in an already injured artery. Antiplatelet medications can prevent this from happening. Antiplatelets may be prescribed to folks with a history of: Coronary artery disease Heart attack Angina (chest pain) Stroke and transient ischemic attacks ( TIAs) Peripheral artery disease Antiplatelets are also used: After angioplasty and stent placement After heart bypass or valve replacement surgery Usually once or twice a day. You shouldn't take them on an empty stomach. Tell your doctor if you're allergic to aspirin, ibuprofen, or naproxen before he prescribes you this medicine. People with bleeding problems, ulcers, or who are planning to have surgery, including dental surgery, should talk to their doctor before taking these. They may cause excessive bleeding. You shouldn't stop taking your antiplatelet drug unless your doctor tells you to. These drugs may need to be taken for the rest of your life, depending on your condition. While taking these, ask your doctor what you can take for pain relief or minor colds. Read the labels of other pain relievers and cold products to make sure they are aspirin-free. Medicines containing aspirin or nonsteroidal anti-inflammatory drugs ( NSAIDs) may cause bleeding problems when taken along with antiplatelet drugs. Before any surgery, dental procedure, or emergency treatment, tell the doctor or dentist that you are taking this medicine. You might need to stop taking it for 5 to 7 days before dental work or surgery. However, don't stop this medicine without first talking with your doctor. Use caution during activities requiring you to be alert (like driving a car) until you know how the drug affects you. Antiplatelets can cause: Nausea Upset stomach Stomach pain Diarrhea Rash Itching To ease nausea and stomach upset, take these with meals. Call your doctor if these side effects are severe or don't go away. Contact your doctor right away if you have any of the following while you take antiplatelets: Blood in the urine or stool Nosebleeds Any unusual bruising Heavy bleeding from cuts Black tarry stools Coughing up of blood Unusually heavy menstrual bleeding or unexpected vaginal bleeding Vomit that looks like coffee grounds Dizziness Severe headache Difficulty swallowing Shortness of breath Difficulty breathing or wheezing Tightness in chest, chest pain Fever, chills, sore throat Swelling of the face or hands Ringing in the ears Severe stomach pain Side effects can be worse in people with asthma and allergies. If you're expecting or trying, let your doctor know before you take an antiplatelet. Taking them during the last two weeks of pregnancy may cause bleeding problems in the baby or mother before and after delivery. Antiplatelets can be passed to the infant through breast milk. However, their effect on nursing infants is unknown. You should discuss this with your doctor and your baby's doctor.