Clopidogrel: antiplatelet tablet, bleeding risks and PPIs

Clopidogrel stops platelets, the small blood cells involved in clotting, from sticking together and forming a dangerous clot. The NHS lists a history of heart attack, stroke, angina, peripheral arterial disease or atrial fibrillation, and having had heart or blood vessel surgery, among the reasons people are given it.

It may be prescribed alongside low-dose aspirin or instead of it. It is available only on prescription, and your doctor decides whether it fits you and for how long.

The standard dose stated by the NHS is 75mg once a day, taken at the same time each day, with or without food. Doctors sometimes give a single higher dose of 300mg or 600mg to start. The length of treatment varies: a few weeks or months for some people, and for others the rest of their life.

For a missed dose, take it straight away if you remember within 12 hours of when it was due; if 12 hours or more have passed, skip it and carry on as normal. Do not take two together. One or two extra tablets are unlikely to do harm, but contact NHS 111 if you have taken more than prescribed.

Most adults aged 18 and over can take clopidogrel. The NHS lists these reasons it may not be suitable: an allergic reaction to it, previous stomach ulcers, recent surgery or serious injury, past bleeding in the brain, bleeding disorders such as haemophilia, liver or kidney problems, and pregnancy or breastfeeding in some circumstances.

If you fall into one of these groups, the prescriber weighs the risk of bleeding against the risk of a clot, and sometimes picks a different medicine.

The most common effect is bleeding more easily: nosebleeds, bruising, heavier periods, or bleeding that takes longer to stop. Diarrhoea, stomach pain and indigestion or heartburn also occur. Persistent indigestion may be a sign of an ulcer, so mention it.

Call 111 for blood in urine, black or bloody stools, yellow skin or eyes, extreme tiredness, infection signs, or any head injury. Go to A&E or call 999 for coughing or vomiting blood, a nosebleed that lasts well beyond 10 to 15 minutes, or a sudden severe headache with confusion, slurred speech or difficulty moving. Do not drive yourself to A&E. Clopidogrel does not affect driving.

Tell prescribers about all your tablets. The NHS names other clot-preventing medicines, including low-dose aspirin, warfarin, rivaroxaban, apixaban, edoxaban, dabigatran, dipyridamole, ticagrelor and prasugrel, as well as ibuprofen-type painkillers, citalopram, rosuvastatin, rifampicin, carbamazepine, efavirenz, pioglitazone and repaglinide.

Heartburn tablets such as omeprazole or esomeprazole may reduce how well clopidogrel works, and lansoprazole is given as an alternative. St John's wort can raise clopidogrel levels. Avoid grapefruit juice. Alcohol up to 14 units a week is permissible, but heavy drinking may irritate the stomach and raise ulcer risk.

Clopidogrel is not often recommended in pregnancy but can be taken if needed, and the NHS says it is not thought to harm the baby, although information is limited. Breastfeeding may be possible for a healthy baby. It does not affect fertility.

Never stop without advice because the risk of a serious cardiovascular event increases. Your doctor may ask you to pause it before surgery or dental work. Alternatives include low-dose aspirin, dipyridamole, ticagrelor and the anticoagulants apixaban, dabigatran, edoxaban, rivaroxaban and warfarin, and the choice depends on your condition.