An antiplatelet medicine that stops platelets clumping by blocking their P2Y12 receptor, taken to prevent clots after a heart attack, stent, stroke or in peripheral artery disease, often alongside aspirin for a defined period.
Tablets 75 mg once daily; a larger loading dose is given in hospital at the start
Onset and duration
Antiplatelet effect within hours of a loading dose, or over several days at the usual daily dose; lasts 5-7 days after stopping as new platelets replace the blocked ones.
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What it is used for
Preventing further events after a heart attack or acute coronary syndrome, usually with aspirin for up to 12 months
After a coronary stent, to stop the stent clotting
After an ischaemic stroke or transient ischaemic attack, as long-term single antiplatelet treatment
Peripheral arterial disease
How it works in the body
Clopidogrel is a prodrug: the liver converts it, largely through the enzyme CYP2C19, into a molecule that binds irreversibly to the P2Y12 receptor on platelets. Without that receptor's signal, platelets cannot be activated by ADP and stick together far less readily. Because the block is permanent for the life of each platelet, the effect lasts about a week after stopping.
Common side effects
Bleeding more easily: nosebleeds, bruising, bleeding gums, longer bleeding from cuts
Diarrhoea, stomach pain, indigestion
Serious: seek help
Serious bleeding: blood in urine or stools, black stools, vomiting blood, a bleed after a head injury
Signs of an allergic reaction
Very rarely, a blood disorder causing fever, bruising and confusion (thrombotic thrombocytopenic purpura)
Cautions and interactions
Tell any doctor, dentist or pharmacist that you take it; it is usually paused before surgery only on the advice of the prescriber
Omeprazole and esomeprazole reduce its activation; other acid-suppressing medicines are preferred if one is needed
Combined with aspirin, warfarin, a DOAC or an NSAID the bleeding risk rises and the combination is decided by the prescriber
Some people convert it poorly (CYP2C19 variants) and get less protection
Interactions
Check interactions
Taking Clopidogrel with other medicines? Add them to the checker to see what the official sources say about each pair: the mechanism, general management and monitoring, never a bare "safe".
Interactions documented in the official sources cited on each card. The list covers the medicines represented on this site and is not exhaustive; how the interaction data is compiled.
Therapeutic duplication. Aspirin with another antiplatelet (dual antiplatelet therapy) is a deliberate, time-limited prescription after stents and acute coronary syndromes; taking two antiplatelets without such an indication adds bleeding risk. UK
Medicines that share the class of Clopidogrel. They are separate medicines with their own licences, doses and interactions, not alternative names for Clopidogrel.
Medicines often discussed alongside Clopidogrel: used together, compared with it, or acting on the same problem by a different route.
Educational content. Anatomy Nexus provides medical education and does not replace professional medical advice, diagnosis, treatment, prescribing or pharmacist review. Doses, choices and monitoring are decided by a prescriber for an individual; never start, stop or change a medicine on the basis of this page.
