Clopidogrel: Uses, Dosage & Side Effects
Antiplatelet medication to prevent blood clots, heart attack and stroke
Quick facts about Clopidogrel
Key takeaways about Clopidogrel
- Prevents blood clots: Clopidogrel irreversibly blocks the P2Y12 receptor on platelets, reducing the risk of heart attack, stroke and cardiovascular death
- WHO Essential Medicine: Listed on the WHO Model List of Essential Medicines as a critical cardiovascular drug
- Avoid omeprazole: Omeprazole and esomeprazole significantly reduce clopidogrel effectiveness – use pantoprazole if a proton pump inhibitor is needed
- Do not stop suddenly: Abrupt discontinuation increases the risk of heart attack or stent thrombosis – always consult your doctor first
- Increased bleeding risk: Cuts and injuries may bleed longer than usual – inform all healthcare providers and dentists that you are taking clopidogrel
What Is Clopidogrel and What Is It Used For?
Clopidogrel is an antiplatelet medication that prevents blood clots by irreversibly inhibiting the P2Y12 ADP receptor on platelets. It is prescribed for adults to reduce the risk of atherothrombotic events including heart attack, stroke and cardiovascular death in patients with established atherosclerosis.
Clopidogrel belongs to a group of medicines called antiplatelet agents (also known as platelet aggregation inhibitors). Platelets are very small cells in the blood that clump together during blood clotting, forming clots. By preventing this clumping, antiplatelet medicines reduce the chances that blood clots will form – a process called thrombosis.
Clopidogrel is a prodrug, which means it must be converted into its active form by enzymes in the liver, primarily CYP2C19. The active metabolite then permanently binds to the P2Y12 receptor on the surface of platelets, blocking adenosine diphosphate (ADP) from activating them. Since platelets have a lifespan of approximately 7 to 10 days, the antiplatelet effect of a single dose of clopidogrel lasts for the remaining life of the affected platelet.
Clopidogrel was first approved for clinical use in 1997 and has become one of the most widely prescribed cardiovascular drugs worldwide. It is included on the WHO Model List of Essential Medicines, reflecting its critical role in global cardiovascular care. The original brand name is Plavix, but numerous generic versions are now available, including Clopidogrel Krka, Clopidogrel Zentiva, Clopidogrel Accord, Grepid, Clopidogrel STADA, Cloriocard and Clopidogrel Medical Valley.
Approved indications
Clopidogrel is prescribed for the following conditions:
- Recent heart attack (myocardial infarction): To prevent further atherothrombotic events after a heart attack
- Recent ischaemic stroke: To reduce the risk of recurrent stroke in patients with a history of ischaemic stroke
- Peripheral arterial disease (PAD): To reduce the risk of atherothrombotic events in patients with established peripheral arterial disease
- Acute coronary syndrome (ACS): In combination with aspirin (dual antiplatelet therapy, or DAPT) for patients with unstable angina or myocardial infarction, including those who have received a coronary stent
- Transient ischaemic attack (TIA) or minor ischaemic stroke: In combination with aspirin for short-term (typically 21 days) dual antiplatelet therapy, followed by clopidogrel monotherapy or aspirin monotherapy as determined by the treating physician
- Atrial fibrillation: In combination with aspirin for patients with atrial fibrillation who cannot take oral anticoagulants (vitamin K antagonists or direct oral anticoagulants) and who do not have a high risk of major bleeding. However, it should be noted that oral anticoagulants are generally more effective than the combination of clopidogrel and aspirin for stroke prevention in atrial fibrillation
The landmark CAPRIE trial (1996) compared clopidogrel 75 mg daily to aspirin 325 mg daily in over 19,000 patients at risk of ischaemic events. Clopidogrel showed a modest but statistically significant 8.7% relative risk reduction in the combined endpoint of ischaemic stroke, myocardial infarction or vascular death compared with aspirin. Clopidogrel also demonstrated a more favourable gastrointestinal safety profile, with fewer cases of gastrointestinal bleeding and peptic ulcers.
What Should You Know Before Taking Clopidogrel?
Before starting clopidogrel, tell your doctor about any bleeding disorders, recent surgery, liver disease, planned procedures, pregnancy, or if you are taking medications that increase bleeding risk. Clopidogrel should not be used if you have active bleeding or severe liver disease.
It is essential to discuss your complete medical history with your doctor before beginning treatment with clopidogrel. Several conditions and circumstances may affect whether clopidogrel is safe and appropriate for you, and your doctor needs this information to make the best treatment decision.
Contraindications
You must not take clopidogrel if:
- You are allergic to clopidogrel or any of the other ingredients in the tablets
- You have an active bleeding condition, such as a bleeding stomach ulcer or bleeding in the brain (haemorrhagic stroke)
- You have severe liver disease that could affect how your blood clots
If you think any of these apply to you, or if you have any doubts, consult your doctor before starting clopidogrel.
Warnings and precautions
Tell your doctor if any of the following situations apply to you before taking clopidogrel:
- You have an increased risk of bleeding, such as a condition that puts you at risk of internal bleeding (e.g. stomach ulcer), a blood disorder that increases the risk of internal bleeding (in tissues, organs or joints), or a recent serious injury
- You have had recent surgery (including dental surgery) or have a planned operation within the next 5 to 7 days. Clopidogrel is typically stopped before elective procedures to reduce bleeding risk
- You have had a blood clot in a brain artery (ischaemic stroke) within the past 7 days
- You have kidney or liver disease
- You have previously had a non-traumatic brain haemorrhage
- You have had an allergic reaction to any other antiplatelet medicine (such as ticlopidine or prasugrel)
In rare cases, clopidogrel can cause a serious condition called thrombotic thrombocytopenic purpura (TTP). Seek immediate medical attention if you develop fever, bruising under the skin that may appear as red pinpoint spots, unexplained severe weakness, confusion, or yellowing of the skin or eyes (jaundice). TTP requires urgent treatment.
While taking clopidogrel, you should be aware that cuts and injuries may bleed longer than usual. This is a natural consequence of how the medicine works – by preventing blood clots from forming. For minor cuts and scrapes (such as during shaving), this is usually not a problem. However, if you are concerned about any bleeding, contact your doctor immediately.
Pregnancy and breastfeeding
Clopidogrel should preferably not be taken during pregnancy. If you are pregnant or suspect you might be pregnant, tell your doctor or pharmacist before starting treatment. If you become pregnant while taking clopidogrel, contact your doctor immediately, as the use of clopidogrel during pregnancy is not recommended due to insufficient safety data in humans.
You should not breastfeed while taking clopidogrel. Studies in animals have shown that clopidogrel and its metabolites are excreted in breast milk. If you are breastfeeding or planning to breastfeed, speak with your doctor before taking this medicine. Your doctor will weigh the benefits of treatment against the potential risks to your baby.
Children and adolescents
Clopidogrel is not recommended for use in children and adolescents under 18 years of age. Clinical trials in paediatric patients have not demonstrated a favourable benefit-risk profile compared to adults, and the medicine is not approved for use in this age group.
Driving and using machines
Clopidogrel is unlikely to affect your ability to drive or operate machinery. No studies have shown any impairment of cognitive or motor function at the recommended dose.
Lactose content
Some clopidogrel formulations contain lactose as an excipient. If you have been told by your doctor that you have an intolerance to some sugars, contact your doctor before taking this medicine.
How Does Clopidogrel Interact with Other Drugs?
Clopidogrel has clinically significant interactions with proton pump inhibitors (especially omeprazole and esomeprazole), oral anticoagulants, NSAIDs, SSRIs and several other medications. The most important interaction is with omeprazole, which can reduce the antiplatelet effect of clopidogrel by up to 45%.
Tell your doctor or pharmacist about all medicines you are taking, have recently taken, or might take – including over-the-counter medicines, herbal products and supplements. Some medicines can affect how clopidogrel works, and clopidogrel can affect how other medicines work. Understanding these interactions is critical for safe and effective treatment.
Major interactions
The following drug interactions are considered clinically significant and may require dose adjustment, monitoring or avoidance:
| Drug / Class | Interaction | Clinical Significance | Recommendation |
|---|---|---|---|
| Omeprazole, Esomeprazole | Inhibit CYP2C19, reducing conversion of clopidogrel to its active metabolite | Up to 45% reduction in antiplatelet effect | Avoid. Use pantoprazole or lansoprazole instead |
| Oral anticoagulants (warfarin, rivaroxaban, apixaban) | Increased bleeding risk through additive anticoagulant and antiplatelet effects | Significantly increased bleeding risk | Avoid combination unless specifically indicated; close monitoring required |
| NSAIDs (ibuprofen, naproxen, diclofenac) | Increased risk of gastrointestinal bleeding | Significant increase in GI bleeding risk | Avoid long-term use; use paracetamol for pain when possible |
| Heparin (and low-molecular-weight heparins) | Additive anticoagulant effect | Increased bleeding risk | Use with caution; monitor for signs of bleeding |
| SSRIs (fluoxetine, fluvoxamine, sertraline) | SSRIs impair platelet function and fluoxetine/fluvoxamine inhibit CYP2C19 | Increased bleeding risk | Monitor for bleeding; consider alternatives to fluoxetine/fluvoxamine |
| Fluconazole, Voriconazole | Inhibit CYP2C19, reducing clopidogrel activation | Reduced antiplatelet effect | Avoid if possible; discuss alternatives with your doctor |
Other notable interactions
The following interactions are also worth noting, though they are generally of lower clinical significance or may only apply in specific situations:
- Aspirin (acetylsalicylic acid): Clopidogrel is frequently co-prescribed with aspirin (dual antiplatelet therapy). Occasional use of aspirin (up to 1000 mg in 24 hours) is generally not a problem, but long-term use should only occur under medical supervision. The combination increases bleeding risk but provides superior protection against atherothrombotic events in certain clinical settings
- Rifampicin: A strong CYP2C19 and CYP3A4 inducer that may paradoxically increase clopidogrel activation. The clinical significance is unclear, and monitoring is recommended
- Carbamazepine: May reduce clopidogrel plasma levels through enzyme induction
- Repaglinide: Clopidogrel inhibits CYP2C8, potentially increasing repaglinide levels and the risk of hypoglycaemia in diabetic patients
- Paclitaxel: Clopidogrel may affect the metabolism of paclitaxel; inform your oncologist if you are taking both
- Opioids: Opioids may delay the absorption and reduce plasma levels of clopidogrel, potentially reducing its effectiveness. Inform your doctor if you need opioid treatment while taking clopidogrel
- Rosuvastatin: Clopidogrel may increase rosuvastatin exposure. Your doctor may need to adjust the statin dose
- Efavirenz and other antiretrovirals: Some HIV medications may affect CYP2C19 activity and alter clopidogrel effectiveness
Approximately 2% of White Europeans, 4% of Black Africans and up to 14% of Chinese individuals are CYP2C19 poor metabolisers, meaning they cannot effectively convert clopidogrel into its active form. These patients may have a reduced antiplatelet response and a higher risk of cardiovascular events. Pharmacogenomic testing for CYP2C19 status can help guide treatment decisions. If you are identified as a poor metaboliser, your doctor may consider alternative antiplatelet agents such as prasugrel or ticagrelor.
Food interactions
Clopidogrel can be taken with or without food. There are no clinically significant food interactions. Grapefruit juice has a theoretical potential to affect CYP3A4 metabolism, but this is not considered clinically significant for clopidogrel at normal dietary intake levels.
What Is the Correct Dosage of Clopidogrel?
The standard adult dose of clopidogrel is 75 mg once daily, taken by mouth with or without food. A loading dose of 300 mg (or sometimes 600 mg) may be given at the start of treatment for acute coronary syndrome or before coronary stenting. Always take clopidogrel exactly as prescribed by your doctor.
The correct dose of clopidogrel depends on your specific medical condition and what your doctor has prescribed. Always follow your doctor's or pharmacist's instructions. If you are unsure, ask your doctor or pharmacist for clarification.
Adults
| Indication | Loading Dose | Maintenance Dose | Duration |
|---|---|---|---|
| Recent MI, stroke or PAD | None | 75 mg once daily | Long-term (as directed) |
| Acute coronary syndrome (with stent) | 300 mg single dose | 75 mg once daily + aspirin | 6–12 months (DAPT) |
| Acute coronary syndrome (no stent) | 300 mg single dose | 75 mg once daily + aspirin | Up to 12 months |
| TIA or minor ischaemic stroke | 300 mg single dose | 75 mg once daily + aspirin | 21 days DAPT, then monotherapy |
| Atrial fibrillation (if OAC unsuitable) | None | 75 mg once daily + aspirin | Long-term (as directed) |
Take your clopidogrel tablet at the same time each day, with or without food. Swallow the tablet whole with a glass of water. Do not crush, chew or break the tablet unless your doctor has specifically advised you to do so.
Children
Clopidogrel is not approved for use in children and adolescents under 18 years of age. Do not give this medicine to children, as it has not been shown to be effective in this age group.
Elderly
No dose adjustment is required for elderly patients. The standard dose of 75 mg once daily applies to patients of all ages. However, elderly patients may have a higher risk of bleeding and should be monitored more closely.
Missed dose
If you forget to take a dose of clopidogrel:
- If you notice within 12 hours of the missed time, take the tablet as soon as you remember, then take the next tablet at the usual time
- If more than 12 hours have passed, simply skip the missed dose and take your next dose at the regular time
- Do not take a double dose to make up for a forgotten tablet
If you are unsure what to do, contact your doctor or pharmacist for advice.
Overdose
If you take too much clopidogrel, contact your doctor or go to the nearest emergency department immediately because of the increased risk of bleeding. Symptoms of overdose may include prolonged bleeding time and subsequent bleeding complications. There is no specific antidote for clopidogrel. If rapid reversal of the antiplatelet effect is necessary, a platelet transfusion may be considered.
Do not stop taking clopidogrel unless your doctor tells you to. Stopping clopidogrel abruptly – especially if you have a coronary stent – can dramatically increase your risk of heart attack or stent thrombosis, which can be life-threatening. If you experience side effects that concern you, speak with your doctor about managing them rather than stopping the medicine on your own.
What Are the Side Effects of Clopidogrel?
The most common side effect of clopidogrel is bleeding, which may present as bruising, nosebleeds, gastrointestinal bleeding or blood in the urine. Other common side effects include diarrhoea, abdominal pain and indigestion. Serious but rare side effects include TTP, severe liver problems and severe allergic reactions.
Like all medicines, clopidogrel can cause side effects, although not everybody gets them. The most important side effect to be aware of is an increased tendency to bleed. Below is a comprehensive overview of side effects organised by frequency.
- Fever, signs of infection or severe weakness – this may be due to a rare decrease in certain blood cells
- Signs of liver problems such as yellowing of the skin and/or eyes (jaundice), with or without small pinpoint bleeding under the skin and/or confusion
- Swelling of the mouth or skin disorders such as rash, itching or blistering of the skin – these may be signs of an allergic reaction
Bleeding
The most commonly reported side effect of clopidogrel is bleeding. Bleeding can occur as gastrointestinal bleeding, bruising, haematoma (unusual bleeding or bruising under the skin), nosebleed, or blood in the urine. A small number of cases of bleeding in the eye, inside the head (intracranial haemorrhage), the lungs or the joints have also been reported.
If you cut or injure yourself while taking clopidogrel, it may take longer than usual for the bleeding to stop. This is directly related to how the medicine works – it prevents blood clots from forming. For minor cuts and scrapes, this is usually not a concern. However, if you are worried about any bleeding, contact your doctor immediately.
Side effects by frequency
Common (up to 1 in 10 people)
- Diarrhoea
- Abdominal pain
- Indigestion (dyspepsia)
- Heartburn
- Bruising
- Nosebleeds
Uncommon (up to 1 in 100 people)
- Headache
- Stomach ulcer
- Vomiting
- Nausea
- Constipation
- Increased gas (flatulence)
- Rash
- Itching (pruritus)
- Dizziness
- Tingling and numbness (paraesthesia)
Rare (up to 1 in 1,000 people)
- Vertigo
- Gynaecomastia (breast enlargement in men)
Very rare (up to 1 in 10,000 people)
- Jaundice (yellowing of skin/eyes)
- Severe abdominal pain with or without back pain
- Fever
- Breathing difficulties, sometimes with cough
- Generalised allergic reactions (e.g. feeling of warmth with sudden general discomfort, including fainting)
- Swelling in the mouth
- Blistering of the skin
- Skin allergy
- Mouth soreness (stomatitis)
- Decreased blood pressure
- Confusion
- Hallucinations
- Joint pain
- Muscle pain
- Taste changes or loss of taste
Additionally, your doctor may find changes in your blood or urine test results during treatment with clopidogrel. These may include changes in platelet counts, white blood cell counts or liver enzyme levels.
If you experience any side effects, talk to your doctor or pharmacist. This includes any possible side effects not listed here. You can also report side effects directly to your national pharmacovigilance authority. By reporting side effects, you help provide more information on the safety of this medicine.
How Should You Store Clopidogrel?
Store clopidogrel out of the sight and reach of children. Do not use after the expiry date on the packaging. Store below 30°C for PVC/PVDC/aluminium blisters; no special storage conditions for all-aluminium blisters.
Proper storage of clopidogrel is important to ensure the medicine remains effective and safe to use throughout its shelf life. Follow these guidelines:
- Keep out of the sight and reach of children at all times
- Do not use after the expiry date printed on the carton and blister after “EXP”. The expiry date refers to the last day of that month
- For PVC/PVDC/aluminium blisters: Store below 30°C
- For all-aluminium blisters: No special storage conditions are required
- Do not use the medicine if you notice any visible signs of deterioration such as discolouration, crumbling or unusual odour
- Do not dispose of medicines via wastewater or household waste. Ask your pharmacist how to dispose of medicines you no longer use. These measures help to protect the environment
What Does Clopidogrel Contain?
Each film-coated tablet contains 75 mg of clopidogrel (as clopidogrel hydrogen sulfate). Inactive ingredients include mannitol, hydrogenated castor oil, microcrystalline cellulose, macrogol 6000 and the film coating contains lactose monohydrate.
Active ingredient
Each tablet contains 75 mg of clopidogrel (as clopidogrel hydrogen sulfate, also known as clopidogrel bisulfate). The hydrogen sulfate salt form is used to improve the stability and bioavailability of the active ingredient.
Inactive ingredients (excipients)
The inactive ingredients in a typical clopidogrel 75 mg film-coated tablet include:
- Tablet core: Mannitol (E421), hydrogenated castor oil, microcrystalline cellulose, macrogol 6000 and low-substituted hydroxypropylcellulose
- Film coating: Lactose monohydrate, hypromellose (E464), triacetin (E1518), red iron oxide (E172) and titanium dioxide (E171)
- Polishing agent: Carnauba wax
Note that the exact excipient composition may vary between different generic manufacturers. If you have known allergies or intolerances to specific excipients (particularly lactose or hydrogenated castor oil, which may cause stomach upset or diarrhoea), discuss this with your doctor or pharmacist. They can help identify a formulation that is suitable for you.
Appearance
Clopidogrel 75 mg film-coated tablets (Zentiva formulation) are round, biconvex and pink, marked with “75” on one side and “1171” on the other. The appearance may differ between generic brands. Available pack sizes typically include 7, 14, 28, 30, 50, 84, 90 and 100 tablets, as well as 50×1 unit-dose perforated blisters. Not all pack sizes may be marketed in all countries.
Frequently Asked Questions About Clopidogrel
Clopidogrel is an antiplatelet medication used to prevent blood clots (thrombosis) in patients with atherosclerosis. It is prescribed after heart attacks, strokes, or for peripheral arterial disease. It is also used in combination with aspirin (dual antiplatelet therapy) after coronary stent placement, acute coronary syndrome, and recent minor ischaemic stroke or transient ischaemic attack (TIA). Clopidogrel works by irreversibly blocking the P2Y12 receptor on platelets, preventing them from clumping together and forming dangerous blood clots.
Omeprazole and esomeprazole should be avoided with clopidogrel because they inhibit CYP2C19, the liver enzyme needed to convert clopidogrel to its active form. This interaction can reduce the antiplatelet effect of clopidogrel by up to 45%, potentially increasing the risk of cardiovascular events. If you need a proton pump inhibitor (PPI) for stomach protection, your doctor may prescribe pantoprazole or lansoprazole instead, as these have less interaction potential with clopidogrel.
Treatment duration depends on your specific condition. After a coronary stent, dual antiplatelet therapy (clopidogrel plus aspirin) is typically continued for 6 to 12 months. After an acute coronary syndrome without stenting, it is usually 12 months. For stroke prevention or peripheral arterial disease, clopidogrel may be prescribed on a long-term basis. After a TIA or minor stroke, dual therapy is typically 21 days followed by monotherapy. Never stop taking clopidogrel without consulting your doctor, as abrupt discontinuation significantly increases the risk of heart attack or stent thrombosis.
If you miss a dose and it has been less than 12 hours since you should have taken it, take the tablet as soon as you remember, then take your next dose at the regular time. If more than 12 hours have passed, skip the missed dose entirely and take your next dose at the regular scheduled time. Never take a double dose to compensate for a forgotten tablet. If you are unsure, contact your doctor or pharmacist for guidance.
The most common side effect of clopidogrel is bleeding, which may present as bruising, nosebleeds, blood in the urine, or gastrointestinal bleeding. Other common side effects include diarrhoea, abdominal pain, indigestion and heartburn. Uncommon effects include headache, rash, itching, and dizziness. Serious but rare side effects include thrombotic thrombocytopenic purpura (TTP), severe liver problems and severe allergic reactions. Contact your doctor immediately if you experience unusual bleeding, fever, confusion, or yellowing of the skin or eyes.
Yes, clopidogrel usually needs to be stopped 5 to 7 days before elective surgery, including dental procedures, to reduce the risk of excessive bleeding during and after the operation. However, stopping clopidogrel increases the risk of blood clots, especially if you have a coronary stent. Never stop clopidogrel on your own – always discuss with both your surgeon and the doctor who prescribed the medication. For emergency surgery, the surgical team will take appropriate precautions to manage the increased bleeding risk.
References
This article is based on the following peer-reviewed sources, international guidelines and regulatory documents:
- European Medicines Agency (EMA). Clopidogrel Summary of Product Characteristics (SmPC). EMA, 2024. Available at: www.ema.europa.eu
- CAPRIE Steering Committee. A randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE). The Lancet. 1996;348(9038):1329-1339.
- Yusuf S, et al. Effects of clopidogrel in addition to aspirin in patients with acute coronary syndromes without ST-segment elevation (CURE Trial). New England Journal of Medicine. 2001;345(7):494-502.
- Bhatt DL, et al. Clopidogrel with or without omeprazole in coronary artery disease (COGENT Trial). New England Journal of Medicine. 2010;363(20):1909-1917.
- Byrne RA, et al. 2023 ESC Guidelines for the management of acute coronary syndromes. European Heart Journal. 2023;44(38):3720-3826.
- Virani SS, et al. 2023 AHA/ACC/ACCP/ASPC/NLA/PCNA Guideline for the Management of Patients With Chronic Coronary Disease. Journal of the American College of Cardiology. 2023;82(9):833-955.
- World Health Organization. WHO Model List of Essential Medicines – 23rd List. WHO, 2023.
- British National Formulary (BNF). Clopidogrel monograph. National Institute for Health and Care Excellence, 2024.
- U.S. Food and Drug Administration. Plavix (clopidogrel bisulfate) FDA Label. FDA, 2024.
- Scott SA, et al. Clinical Pharmacogenetics Implementation Consortium Guidelines for CYP2C19 Genotype and Clopidogrel Therapy: 2013 Update. Clinical Pharmacology & Therapeutics. 2013;94(3):317-323.
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This article has been written and reviewed by the iMedic Medical Editorial Team, consisting of licensed physicians with specialist training in clinical pharmacology, cardiovascular medicine and internal medicine.
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