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Drug Class: Commonly Known As: Category:
Anticoagulant Marevan® Adult

Warfarin - Side Effects, Precautions, and Contraindications

What side effects can Warfarin cause?

  • Possible side effects of Warfarin include:
    • Unexplained nose bleed
    • Bleeding from gums when brushing teeth
    • Prolonged bleeding from minor cuts (10-15 minutes) despite applying pressure on wound. Action: Check with your doctor if the bleeding does not stop within 15 min or if you feel unwell
    • Excessive menstrual bleeding (women) Action: For women, increased menstrual flow is common but check with your doctror if you feel unwell.
    Serious side effects of warfarin overdose include:
    • Blood in urine or cloudy and dark urine
    • Black, sticky or tarry stool (not due to iron supplement)
    • Coughing up blood or coffee ground-like vomit
    • Unexplained large bruises or purplish area on skin
    • Sudden severe headache with nausea or loss of consciousness Action: Check with your doctor immediately or admit yourself to the Accident and Emergency Department (A&E) if you experience any of the symptoms or feel unwell

Before taking Warfarin , what precautions must I follow?

What food or medicine must I avoid when I take Warfarin ?

  • Effect of warfarin depends on the amount of Vitamin K in your body which is mostly derived from your diet
  • Eat a well-balanced diet while you are on warfarin
  • Ensure consistent and moderate consumption of Vitamin K rich food (Refer to the table at the bottom of this page)
  • Avoid making any MAJOR CHANGES to your diet (e.g. becoming a vegetarian) without first consulting your doctor or pharmacist
  • Avoid excessive alcohol consumption. It is advisable not to take more than 5 cans of beer or 1 bottle of wine per week
  • Avoid any form of traditional or herbal remedies and over-the-counter supplements (e.g. gingko, garlic, cordyceps and ginseng) as their effect on warfarin is unpredictable
  • Consult your doctor or pharmacist before you start or stop taking any medication or supplements. Certain medications like pain killers, antibiotics, and hormonal

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