Clopidogrel belongs to the class of medications called platelet aggregation inhibitors or antiplatelets. Clopidogrel is used to help prevent heart attacks, strokes, and other circulation problems for people who have atherosclerosis (narrowed blood vessels caused by "hardening of the arteries") and have already experienced at least one atherothrombotic event such as heart attack or stroke, or have been diagnosed with peripheral arterial disease (problems with blood flow in the arteries). It is also used with ASA (acetylsalicylic acid) by people with acute coronary syndrome or atrial fibrillation (a fast, irregular heartbeat) to reduce the risk of heart attack or stroke.

Normally, platelets help the blood to clot when needed, such as after an injury. When arteries become narrowed by fat deposits (plaques), platelets often clump together in the vessels. Unstable plaques can rupture, leading to additional platelet clumping that can cause a larger blockage of the artery. This further narrows the arteries and increases the chances of heart attack, stroke, or other circulation problems. Clopidogrel reduces the chances of these events by preventing platelets from forming into clumps.

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 adult dose of clopidogrel for most conditions is 75 mg once daily. When used by people with acute coronary syndromes, a 300 mg "loading dose" is initially prescribed. After this, treatment starts with 75 mg of clopidogrel once daily.

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.

Clopidogrel may be taken with or without food.

It is important that this medication be taken exactly as prescribed by your doctor. If you miss a dose within 12 hours of your usual time, take it as soon as possible and continue with your regular dosing schedule. If it is more than 12 hours, 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.

Each pink, round, biconvex, film-coated tablet, engraved with "CL" over "75" on one side and plain on the other, contains clopidogrel bisulfate equivalent to 75 mg of clopidogrel. Nonmedicinal ingredients: anhydrous lactose, methylcellulose, crospovidone, colloidal silicon dioxide, zinc stearate, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, polyethylene glycol, titanium dioxide, and red ferric oxide (orange shade).

Do not take clopidogrel if you:

• are allergic to clopidogrel or any ingredients of the medication
• have an active bleeding condition such as a stomach ulcer or a brain hemorrhage
• have significant liver disease or cholestatic jaundice
• are taking the medication repaglinide

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.

• changed sense of taste
• constipation
• diarrhea
• dizziness
• headache
• heartburn
• joint or muscle pain
• nausea
• vomiting

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:

• abdominal pain
• enlargement of breast tissue in men
• flu-like symptoms (sudden lack of energy, fever, cough, sore throat)
• symptoms of pneumonia (e.g., cough, fever, trouble breathing, night sweats)
• signs of bleeding (e.g., nosebleeds, blood in urine, coughing blood, bleeding gums, unusual bruising or bleeding)
• signs of infection (symptoms may include fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)
• skin rash or itching
• symptoms of liver problems (i.e., yellowing of the skin or eyes, dark urine, light coloured stools, vomiting, nausea, abdominal pain)
• symptoms of low blood sugar (e.g., cold sweat, cool pale skin, headache, fast heartbeat, weakness)
• tingling sensation in the hands, arms, feet, or legs

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

• chest pain
• signs of bleeding in the brain (e.g., sudden severe headache, weakness, loss of speech or vision, confusion, seizures, loss of consciousness)
• signs of bleeding in the stomach (e.g., bloody, black, or tarry stools; spitting up blood; vomiting blood or material that looks like coffee grounds)
• signs of a serious allergic reaction (i.e., swelling of face or throat, hives, or difficulty breathing)
• signs of stroke (e.g., sudden or severe headache; sudden loss of coordination; vision changes; sudden slurring of speech; or unexplained weakness, numbness, or pain in arm or leg)

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.

Allergy: Some people who are allergic to other antiplatelet medications such as ticlopidine or prasugrel also experience allergic reactions to clopidogrel. Before you take clopidogrel, tell your doctor about any previous adverse reactions you have had to medications, especially anti-platelet medications. Contact your doctor at once if you experience signs of an allergic reaction, such as skin rash, itching, difficulty breathing, or swelling of the face and throat.

Bleeding problems: Clopidogrel increases the risk of bleeding. Using other medications (e.g., certain antidepressants, NSAIDs) may further increase the risk of bleeding. If you have a history of bleeding disorders, 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. If you experience signs of serious or excessive bleeding (e.g., bleeding from rectum, easy bruising, bloody urine, dark stools, persistent abdominal pain and vomiting), contact your doctor immediately.

Thrombotic thrombocytopenic purpura is a rare condition that may occur while taking clopidogrel and requires immediate medical attention. Symptoms include decreased number of blood cells, reduced kidney function, and fever. Seek immediate medical attention if you experience any of these symptoms while taking this medication.

Blood glucose: When combined with clopidogrel, certain medications for type 2 diabetes (repaglinide) cause dangerously low blood glucose levels. If you have type 2 diabetes, 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.

Kidney function: If you have reduced kidney function or kidney disease, 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.

Lactose intolerance: This medication contains lactose. If you have galactose intolerance (galactosemia, glucose-galactose malabsorption, or Lapp lactase deficiency) you should not take this medication.

Liver function: Liver disease or decreased liver function can affect how this medication works for you. If you have reduced liver function or liver disease, 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.

People with severely reduced liver function should not take clopidogrel.

Proton pump inhibitors: Proton pump inhibitors (PPIs) are medications such as omeprazole and lansoprazole that are taken to treat stomach ulcers and severe heartburn. When clopidogrel is taken by people who are also taking a PPI, clopidogrel may be less effective, depending on the PPI that is used. If you are taking a medication in this class, discuss with your doctor whether you should continue to take it, or whether another medication may be more appropriate.

Stomach problems: Since clopidogrel can increase the risk of bleeding and slow down the time it takes to form a clot, it is important to remind your doctor if you have had stomach ulcers. Ask the doctor or your pharmacist to review your medications if they may cause stomach ulcers (e.g., NSAIDs such as ibuprofen, naproxen, and others).

Surgery: Your doctor may want to stop clopidogrel for a several days prior to any planned surgery to prevent any unnecessary bleeding, so it is important to tell all of your doctors that you are taking clopidogrel.

Pregnancy: The 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: It is not known if clopidogrel passes into breast milk. If you are breast-feeding and taking this medication, 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 clopidogrel and any of the following:

• acetylsalicylic acid (ASA)
• anagrelide
• anticoagulants (e.g., apixaban, dabigatran, edoxaban, enoxaparin, heparin, rivaroxaban, warfarin)
• other antiplatelet medications (e.g., prasugrel, ticagrelor)
• apalutamide
• "azole" antifungals (e.g., fluconazole, voriconazole)
• bismuth subsalicylate
• bupropion
• cannabis
• calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
• cladribine
• cobicistat
• defibrotide
• desloratadine
• enzalutamide
• erythromycin
• etravirine
• fentanyl
• ginger
• ginkgo biloba
• ginseng
• grapefruit juice
• icosapent ethyl
• moclobemide
• morphine
• multivitamins with or without minerals
• nirmatrelvir and ritonavir
• nonsteroidal anti-inflammatories (NSAIDs; e.g., ibuprofen, diclofenac, ketorolac, naproxen)
• obinutuzumab
• omega-3 fatty acids
• oseltamivir
• ozanimod
• paclitaxel
• pentosan polysulfate sodium
• pentoxifylline
• pioglitazone
• certain protein kinase inhibitors (e.g., acalabrutinib, dabrafenib, dasatinib, ibrutinib, pazopanib)
• proton pump inhibitors (PPIs; e.g., esomeprazole, lansoprazole, omeprazole, pantoprazole)
• repaglinide
• rifampin
• ritonavir
• rosuvastatin
• saw palmetto
• selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, fluoxetine, paroxetine, sertraline, vortioxetine)
• selexipag
• serotonin-norepinephrine reuptake inhibitors (SNRIS; desvenlafaxine, duloxetine, venlafaxine)
• stiripentol
• tipranavir
• topotecan
• ubrogepant
• vilazodone
• vitamin E

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.