Acenocoumarol - an anticoagulant

  • You will be given an anticoagulant record book; read this carefully, and carry it with you at all times.
  • You will need regular blood tests to check your INR (International Normalised Ratio) - these tests are very important.
  • Do not drink cranberry juice.
  • Some medicines bought over the counter may interfere with acenocoumarol. Check with your pharmacist before you buy any painkillers or vitamins.
Type of medicine Anticoagulant
Used for Prevention and treatment of harmful blood clots
Also called Sinthrome®
Available as Tablets

Acenocoumarol is an anticoagulant, which means that it increases the time it takes for your blood to clot. It works by reducing the effects of vitamin K, which is a vitamin your body uses in the process of blood-clotting.

Acenocoumarol is used to prevent unwanted clots from forming if you have a condition that puts you at risk of this happening. It is also used to prevent any clots that may have already formed in the blood vessels of your legs, lungs or heart from becoming larger and causing problems. Another anticoagulant, called warfarin, is usually prescribed in preference to acenocoumarol.

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 acenocoumarol it is important that your doctor or pharmacist knows:

  • If you are pregnant, trying for a baby or breast-feeding.
  • If you have liver or kidney problems.
  • If you have had a stomach ulcer.
  • If you have recently had a stroke.
  • If you have any cuts or wounds.
  • If you have high blood pressure.
  • If you have had surgery recently, or are due for surgery in the near future.
  • If you have been told you have an infection of your heart, called bacterial endocarditis.
  • If you are taking or using any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • If you have ever had an allergic reaction to this or to any other medicine.
  • Before you start this treatment, read the manufacturer's printed information leaflet from inside your pack of tablets. This leaflet will give you more information about acenocoumarol, and a full list of possible side-effects from taking it.
  • Take acenocoumarol exactly as you have been advised by your doctor or anticoagulant clinic. Try to take your doses of acenocoumarol at the same time each day. This will help keep the levels of acenocoumarol in your blood steady, and will also help you to avoid missing any doses.
  • If you forget to take a dose, take it as soon as you remember. If you do not remember until the following day, skip the missed dose. Do not take two doses together to make up for a forgotten dose, and remember to let your doctor know about any missed doses when you next have your blood test.
  • You will be given an anticoagulant record book; read this carefully, and carry it with you at all times.
  • You will have regular blood tests to check how the acenocoumarol in your blood is working - these blood tests are very important. The extent to which acenocoumarol is working is measured by the INR (International Normalised Ratio), which is a measure of the ability of your blood to prevent clotting. The amount of acenocoumarol that you need to take will depend upon the result of these blood tests, and this is why your dose may change from time to time.
  • Changing your diet suddenly can affect your INR, especially if you begin to eat more vegetables and salad or if you change the amount of fatty foods you eat. Also, you should not begin a weight-reducing diet without discussing this with your doctor first.
  • Only drink alcohol in small amounts, as this can affect the levels of acenocoumarol in your body.
  • Drinking cranberry juice can interfere with acenocoumarol and affect your INR, so it is best if you avoid cranberry juice altogether.
  • If you buy any medicines, check with a pharmacist that they are safe to take with acenocoumarol. For example, you should not take some painkillers (such as aspirin and other anti-inflammatory painkillers) and some vitamin and herbal preparations while you are on acenocoumarol. If you need to take a painkiller, you may take paracetamol.
  • Because acenocoumarol is used to prevent blood clots from forming, you should avoid contact sports and take care not to knock, cut or bruise yourself. Let your doctor know if you have any falls or injuries.
  • You should avoid getting pregnant while you are taking acenocoumarol. If this affects you, make sure you have discussed with your doctor which types of contraception are suitable for you and your partner.
  • If you are having any injections, an operation or any dental treatment, tell the person carrying out the treatment that you are taking acenocoumarol, and show them your anticoagulant record book.

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. These usually improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.

Acenocoumarol side-effects - these affect less than 1 in 1,000 people who take this medicine What can I do if I experience this?
Feeling or being sick, loss of appetite Stick to simple meals until this passes
Loss of hair If this becomes troublesome, speak with your doctor

Important: if you experience either of the following, contact your doctor for advice straightaway:

  • Any unusual bleeding or bruising, or any blood in your urine or stools. This is because your dose of acenocoumarol will need to be checked.
  • An itchy skin rash. This may be a sign of an allergic reaction to acenocoumarol.

If you experience any other symptoms which you think may be due to acenocoumarol, speak with your doctor or pharmacist.

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.
  • Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.
  • This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
  • Never keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
  • If you have any questions about this medicine ask your pharmacist.

Further reading & references

  • British National Formulary; 63rd Edition (Mar 2012) British Medical Association and Royal Pharmaceutical Society of Great Britain, London
  • Manufacturer's PIL, Sinthrome® Tablets 1 mg; Manufacturer's PIL, Sinthrome® Tablets 1 mg, Alliance Pharmaceuticals, The electronic Medicines Compendium. Dated April 2008.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Helen Allen
Current Version:
Peer Reviewer:
Dr John Cox
Last Checked:
19/07/2012
Document ID:
3280 (v23)
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