Warfarin

Warfarin can be taken by mouth as tablets. Your doctor will prescribe an initial starting dose based on your medical history, and this often ranges from 2-5mg daily. Warfarin doses are individualized, and will be adjusted based on your target prothrombin time (i.e. international normalized ratio [INR]). 

Warfarin should be taken at the same time every day. Your doctor should tell you your target INR and for how long you should take Warfarin.

The most common side effect of Warfarin is bleeding. You must tell your doctor if you notice any signs of bleeding like unexplained bruises and nose or gum bleeds, as well as signs of internal bleeding like blood in your urine or stool. 

Warfarin interacts with many medicines, including over-the-counter and prescription medicines. Always check with your doctor or pharmacist before using a new medicine while taking Warfarin.

People who

• are allergic to warfarin or any component of the preparation
• are prone to or have significant bleeding (e.g. with active gastrointestinal ulceration, cerebral aneurysm)
• have undergone or will undergo surgery of the eye or central nervous system
• are pregnant (except at the high risk of clot formation in blood vessels)

In Hong Kong, Warfarin is a prescription only medicine, and requires a prescription from a doctor to be purchased in a pharmacy. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.

For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at https://www.drugoffice.gov.hk