About warfarin sodium
Vitamin K antagonist anticoagulant
Used for
- Prevents and treats blood clots, including deep vein thrombosis and pulmonary embolism.
- Prevents stroke or clots in some people with atrial fibrillation or artificial heart valves.
Usual adult dose
Individualised and adjusted using blood clotting tests (INR); commonly starts at 2–5 mg once daily.
Usual dose in children
Individualised by age, weight, condition, and INR; specialist supervision is required.
Common side effects
- Bleeding or bruising
- Nausea, vomiting, or diarrhoea
- Skin rash or hair loss
- Rarely, painful skin damage or tissue injury
Important warnings
- Can cause serious or fatal bleeding; seek urgent care for unusual or severe bleeding.
- Requires regular INR blood tests; dose changes and missed doses need careful management.
- Keep vitamin K intake consistent; major diet changes, illness, or alcohol changes can affect INR.
- Tell healthcare professionals before procedures; do not stop or change the dose without clinical guidance.
Pregnancy
Can cause miscarriage, birth defects, or fetal bleeding; generally avoided in pregnancy except specialist-managed situations.
Breastfeeding
Usually compatible with breastfeeding; monitor as advised by a healthcare professional.
Interactions
- Many medicines affect INR, including antibiotics, antifungals, aspirin, and anti-inflammatory painkillers.
- Herbal products and supplements, including St John’s wort, can alter warfarin effects.
- Vitamin K-rich foods can change INR if intake varies substantially.
- Alcohol may alter bleeding risk and INR.
AI-generated from general medical knowledge, not from this product's official leaflet. It may be incomplete or out of date. Not medical advice — ask a pharmacist or doctor before making any decision.