Warfarin

Blood thinner (anticoagulant)
PRESCRIPTION ONLY IN INDIA

Warfarin is a blood thinner (anticoagulant) found in 1 medicine sold in India, such as Warf 5. Below: what it is for, how it works, how to take it, side effects, interactions and pregnancy advice.

What it is used for

Prevents dangerous blood clots, for example with irregular heartbeat or valve replacement.

How it works

An anticoagulant that blocks vitamin K-dependent clotting factors. Its effect is measured by the INR blood test.

How to take it

Take once a day at the same time (often evening). Dose changes with each INR test. Keep vitamin K foods (green leafy vegetables) steady rather than avoiding them.

Common side effects

  • Bruising
  • Nosebleeds
  • Bleeding gums

Get medical help straight away if

  • Blood in urine or stools, vomiting blood, severe headache, or any bleeding that does not stop
  • A fall or head injury

Be careful

Needs regular INR blood tests; many food and drug interactions; watch for bleeding.

Other medicines and interactions

Very many interactions: antibiotics, antifungals, painkillers (NSAIDs, aspirin), some herbal products (ginkgo, turmeric in large amounts) and alcohol binges can change INR. Check before starting anything new.

Pregnancy and breastfeeding

Harms the baby in pregnancy (especially weeks 6 to 12); switch before conceiving. Safe while breastfeeding.

Brands of Warfarin (1)

Warf 5

Common questions

What is Warfarin used for?

Prevents dangerous blood clots, for example with irregular heartbeat or valve replacement.

How does Warfarin work?

An anticoagulant that blocks vitamin K-dependent clotting factors. Its effect is measured by the INR blood test.

How should I take Warfarin?

Take once a day at the same time (often evening). Dose changes with each INR test. Keep vitamin K foods (green leafy vegetables) steady rather than avoiding them.

What are the side effects of Warfarin?

Common: Bruising, nosebleeds, bleeding gums. Get help straight away for: Blood in urine or stools, vomiting blood, severe headache, or any bleeding that does not stop, a fall or head injury.

Does Warfarin interact with other medicines?

Very many interactions: antibiotics, antifungals, painkillers (NSAIDs, aspirin), some herbal products (ginkgo, turmeric in large amounts) and alcohol binges can change INR. Check before starting anything new.

Is Warfarin safe in pregnancy and breastfeeding?

Harms the baby in pregnancy (especially weeks 6 to 12); switch before conceiving. Safe while breastfeeding.

Does Warfarin need a prescription in India?

Yes. In India it is a prescription (Schedule H) medicine, so a pharmacist should sell it only with a doctor's prescription.

Which brands contain Warfarin?

Warf 5.

Sources and further reading

NHS (UK National Health Service) and MedlinePlus (US National Library of Medicine) are free, reviewed medicine guides. Brand names and doses there may differ from India.

Last reviewed 31 October 2026. Written by Satya Babu from standard prescribing information.

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For information only, not medical advice. This page is a plain-language summary written from standard prescribing information and the public guides linked below. Brands sometimes change their formula, so always check the composition printed on the pack. Doses here are typical adult doses; yours may differ. Do not start, stop or change a medicine without your doctor or pharmacist, and keep all medicines away from children. In an emergency, call 112 (India) or your local emergency number.