Description: Acenocoumarol is an anticoagulant medicine, 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 to make blood-clotting factors.

Acenocoumarol is prescribed to prevent unwanted clots from forming if you have a condition that puts you at risk of this happening, such as atrial fibrillation, or if you have had a heart valve replacement. It is also given 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. However, if warfarin is not suitable for you, you may be prescribed acenocoumarol instead.

Acenocoumarol should not be given to pregnant women and patients with:

  • Bleeding disorders and blood diseases (e.g. hemophilia, leukemia)
  • Peptic ulcer or bleeding in the gastrointestinal tract, urogenital tract or respiratory system
  • Cerebrovascular bleeding, acute pericarditis, pericardial effusion, infective endocarditis, and severe hypertension
  • Recent or potential surgery of the eyes and central nervous system
  • Recent surgery resulting in increased fibrinolytic activity (e.g. surgery of the lung, prostate, uterus)
  • Uncooperative patient (e.g. unsupervised senile, alcoholic, psychotic, with dementia)
  • Severe liver and kidney impairment

Along with their useful effects, most medicines can cause unwanted side effects although not everyone experiences them. The most common side effects are bleeding or bruising, blood in urine and hair loss. You will find a full list in the manufacturer’s information leaflet supplied with your medicine. Speak with your doctor or pharmacist if any of the side effects continue or become troublesome.


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 knows:

  • If you are pregnant, trying for a baby or breastfeeding.
  • If you have any cuts or wounds.
  • If you have a condition that increases your risk of bleeding, such as a stomach ulcer, or if you have had surgery recently, or if you have recently had a stroke.
  • If you have any problems with the way your liver works, or with the way your kidneys work.
  • If you have high blood pressure.
  • 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 a medicine.



Increased effect with:

  • Antiarrhythmics (e.g. amiodarone, quinidine)
  • Antibiotics (e.g. broad spectrum antibiotics, tetracyclines, chloramphenicol)
  • Antifungal (e.g. metronidazole)
  • SSRIs (e.g. citalopram, fluoxetine, sertraline, paroxetine)
  • Anti-gout (e.g. allopurinol)
  • Lipid-regulating drugs (e.g. atorvastatin, fluvastatin, simvastatin)
  • Inhibitors of CYP2C9 isoenzyme

Reduced anticoagulant effect with:

  • Anti-cancer drugs (e.g. azathioprine, 6-mercaptopurine)
  • Antivirals (e.g. ritonavir, nelfinavir)
  • Thiazide diuretics
  • Oral contraceptives
  • Inducers of CYP2C9, CYP2C19, and CYP3A4 isoenzymes

May increase the serum hydantoin concentration of phenytoin

May potentiate the hypoglycemic effect of sulfonylurea derivatives (e.g. glibenclamide, glimepiride)

Overdose symptoms include bleeding, vomiting or couging up of blood, bloody urine (with renal colic), bruising, heavy menstrual bleeding, fast heart beat, low blood pressure, nausea, vomiting, diarrhea, and abdominal pain. If overdose is suspected, bring the victim to the hospital immediately.

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