Warfarin
Also sold as: Coumadin
Usual adult dose
Dose is set by your doctor and adjusted with regular INR blood tests. Usual adult dose is 2 to 10 mg once a day at the same time each day.
Your doctor may give you a different dose. Children's doses depend on weight.
Side effects
Common
- bruising
- nosebleeds
- bleeding gums
Serious — get help
Stop taking it and see a doctor straight away if you notice:
- black stools
- blood in urine
- vomiting blood
- severe headache
- bleeding that does not stop
Do not take it, or take care, if
- Pregnancy (harms the baby)
- Active bleeding or recent bleeding in the brain
- Severe uncontrolled high blood pressure
- People who cannot have regular INR blood tests
- Tell every doctor and dentist that you take warfarin
Interactions
Medicines that can react with this one.
Serious24 medicinesDo not take these together unless your doctor says so.
- Amiodarone
Amiodarone strongly raises the effect of warfarin; the warfarin dose usually needs lowering and INR checks.
- Aspirin
Together they greatly raise the risk of serious bleeding.
- Carbamazepine
Carbamazepine lowers the effect of warfarin; INR must be checked.
- Clarithromycin
Can strongly raise the effect of warfarin; INR must be checked.
- Clopidogrel
Together they greatly raise the risk of serious bleeding.
- Co-trimoxazole
Strongly raises the effect of warfarin and the risk of bleeding; INR must be checked.
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- Diclofenac
Raises the risk of serious stomach and other bleeding.
- Fenofibrate
Fenofibrate raises the effect of warfarin; the warfarin dose may need lowering and INR checks.
- Fluconazole
Fluconazole strongly raises the effect of warfarin; INR must be checked.
- Ibuprofen
NSAIDs with warfarin raise the risk of stomach and other serious bleeding.
- Indometacin
Raises the risk of serious bleeding.
- Ketorolac
Raises the risk of serious bleeding; avoid together.
Moderate33 medicinesTake together only with care. Ask your doctor or pharmacist.
- Allopurinol
Allopurinol can increase the effect of warfarin; INR should be checked.
- Amoxicillin
Can change the effect of warfarin; INR should be checked during the course.
- Amoxicillin + Clavulanic acid
Can change the effect of warfarin; INR should be checked during the course.
- Ampicillin
Minor5 medicinesUsually not a problem, but tell your doctor.
- Cefixime
May slightly raise the effect of warfarin; INR may need checking.
- Ceftriaxone
May raise the effect of warfarin; INR may need checking.
- Ivermectin
A rise in INR has been reported; check INR if both are used.
- Mesalazine
Mesalazine may reduce the effect of warfarin; INR should be checked.