In the blood there are 'sticky' cells called platelets. When you cut yourself, these platelets stick to one another to form a clot to seal the wound. Sometimes platelets stick to each other inside an artery - this is called a thrombus. A thrombus can block a blood vessel, and this is often the cause of a stroke or heart attack. This is more likely to happen if the walls of your arteries have areas which have become thickened with fat deposits, or if you have a fast, irregular heartbeat.

If a thrombus forms in a blood vessel around your heart, this reduces the flow of blood to your heart. The term acute coronary syndrome (ACS) covers a range of disorders that are caused by this underlying problem. If you have been prescribed clopidogrel because you have ACS, it may mean that you have had a heart attack, or that you have angina pain that is not well controlled.

Clopidogrel reduces the stickiness of platelets, and this helps prevent the platelets from sticking to the inside of an artery and forming a thrombus. This reduces the risk of you having a heart attack or stroke, as well as Raynaud's attacks.

Before taking Clopidogrel

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking clopidogrel it is important that your doctor knows:

  • If you are pregnant or breast-feeding
  • If you have a condition which causes bleeding (such as a stomach ulcer), or if you have recently had surgery or an injury
  • If you have any problems with the way your liver works or with the way your kidneys work
  • If you have ever had an allergic reaction to a medicine
  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines

How to take Clopidogrel

  • Before you start taking the tablets, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about clopidogrel and will provide you with a full list of the side-effects which you may experience from taking it
  • Take the tablets exactly as your doctor tells you to. It is likely you will be prescribed one tablet of 75 mg clopidogrel to take each day. Although there are two strengths of clopidogrel tablets available (75 mg and 300 mg), the higher-strength tablet is only given as a first dose in some conditions
  • You can take clopidogrel at whatever time of day you find easiest to remember, but take your doses at the same time of day each day. Most people prefer to take it in the morning, as they find this helps them to remember to take it regularly. You can take the tablet either before or after a meal
  • If you forget to take a dose, take it as soon as you remember. If you do not remember until more than 12 hours after the time the dose should have been taken then skip the forgotten dose. Do not take two doses at the same time to make up for a missed dose

Getting the most from your treatment

  • Try to keep all your regular appointments with your doctor. This is so your doctor can check on your progress
  • Before buying or taking any 'over-the-counter' medicines, check with your pharmacist if the medicine is safe for you to take. You should not take any medicines which contain aspirin or any anti-inflammatory painkiller such as ibuprofen, unless your doctor has told you otherwise. This is because these medicines can increase the risk of bleeding when they are taken with clopidogrel. Many cold and flu remedies contain aspirin or ibuprofen
  • If you are due to have an operation or dental treatment, tell the person carrying out the treatment that you are taking clopidogrel. This is because it is possible that any bleeding may take longer than normal to stop
  • While you are on clopidogrel, it might take longer than normal to stop bleeding if you cut yourself. If this happens and you find it difficult to stop the bleeding, contact your doctor. Also, if you notice any unusual or unexplained bleeding, speak with your doctor about this too

Can clopidogrel cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The following list contains some of the most common ones associated with clopidogrel. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.

Common clopidogrel side-effects (these affect less than one-in 10 people) and what to do:

  • Bleeding, nosebleeds, bruising, bleeding under the skin (blood blisters) - because of the way clopidogrel works, any bleeding may take longer than normal to stop. If this becomes troublesome, let your doctor know
  • Indigestion, tummy (abdominal) pain, diarrhoea - stick to simple meals and avoid rich or spicy foods
  • Important: clopidogrel can occasionally cause unwanted effects which are more serious than the ones listed above. Although these occur only rarely, you should contact your doctor for advice if you feel generally unwell or if you experience any other symptoms which you think may be due to the tablets

How to store clopidogrel

  • Keep all medicines out of the reach and sight of children
  • Store in a cool, dry place, away from direct heat and light

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