The most serious side effect of warfarin is bleeding. You must seek medical attention and have an urgent blood test if you experience any of the following side effects:
- passing blood in your urine or feces,
- passing black feces,
- severe bruising,
- prolonged nosebleeds (lasting longer than 10 minutes),
- blood in your vomit,
- coughing up blood,
- unusual headaches, and
- in women, heavy or increased bleeding during your period, or any other bleeding from the vagina.
You must seek immediate medical attention if you:
- are involved in major trauma (accident),
- experience a significant blow to the head, or
- are unable to stop any bleeding.
Less common side effects of warfarin include:
