BMA Concise Guide to Medicine & Drugs


Brand names Grepid, Plavix

Used in the following combined preparations None


Drug group Antiplatelet drug

Overdose danger rating Medium

Dependence rating Low

Prescription needed Yes

Available as generic Yes


Clopidogrel is an antiplatelet drug that is used to prevent blood clots from forming. It is prescribed to patients who have a tendency to form clots in the fast-flowing blood of the arteries and heart, or those who have had a stroke or heart attack. It is also widely used to prevent clots forming in metal stents inserted into coronary arteries. It may be used alone or in combination with aspirin.

Clopidogrel reduces the sticking together of platelets, which can lead to abnormal bleeding. You should therefore report any unusual bleeding to your doctor at once, and, if you require dental treatment, you should tell your dentist that you are taking clopidogrel.

Adverse effects are common with clopidogrel and are usually associated with bleeding.


Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets.

Frequency and timing of doses Once daily.

Dosage range 75mg; up to 300mg as initial dose in hospital.

Onset of effect 1 hour.

Duration of action Antiplatelet effect may last up to 1 week.

Diet advice None.

Storage Keep in original container at room temperature out of the reach of children.

Missed dose Take as soon as you remember. If your next dose is due within 4 hours, take a single dose now and skip the next.

Stopping the drug Do not stop taking the drug without consulting your doctor. Stopping the drug may lead to a recurrence of the original condition.

Exceeding the dose An occasional unintentional extra dose is unlikely to be a cause for concern. But if you notice any unusual symptoms, or if a large overdose has been taken, notify your doctor.


The most frequent adverse effects of clopidogrel are bruising and bleeding, such as nosebleeds or, less commonly, blood in the urine or faeces. Diarrhoea and abdominal pain are also fairly common. Rare adverse effects include nausea, vomiting, headache, dizziness, constipation, rash, itching, sore throat, or fever. You should report any unusual bleeding or bruising, rash or itching, sore throat, or fever to your doctor at once.


Aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) Clopidogrel increases the effect of aspirin on platelets. The risk of gastrointestinal bleeding is increased when clopidogrel is used with these drugs.

Anticoagulant drugs (e.g. warfarin) The risk of bleeding with these drugs is increased if they are taken with clopidogrel.

Proton pump inhibitors (e.g. omeprazole) These may reduce the antiplatelet effect of clopidogrel and should not be used with clopidogrel.


Be sure to tell your doctor if:

· You have liver or kidney problems.

· You have a history of peptic ulcers.

· You have a bleeding disorder.

· You are taking other medicines.

Pregnancy Safety in pregnancy not established. Discuss with your doctor.

Breast-feeding The drug passes into the breast milk and may affect the baby. Discuss with your doctor.

Infants and children Not recommended.

Over 60 No special problems.

Driving and hazardous work No special problems.

Alcohol Avoid. Alcohol can irritate the stomach and increase the risk of bleeding.

Surgery and general anaesthetics Clopidogrel may need to be stopped a week before surgery. Discuss this with your doctor or dentist.


No special problems.