Before you begin using a medication, be sure to inform your doctor of any medication conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use Warfarin.

Bleeding: The most serious risk associated with warfarin is bleeding in any tissue or organ. The risk of bleeding is related to how much is taken and for how long.

It is extremely important to have regular blood tests (as recommended by your doctor) to ensure that the correct level of blood thinning is occurring. These blood tests measure your INR level to determine the dose of warfarin. Your health care provider will adjust the dose of warfarin depending on the INR level to ensure you are not receiving too little medication (which may result in blood clots forming) or too much medication (which may result in bleeding).

Congestive heart failure: People with congestive heart failure may be more sensitive to the effects of warfarin. If you have any heart problems, discuss with your doctor how Warfarin may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Warfarin, and whether any special monitoring is needed.

Dental or surgical treatment: It may be necessary to stop taking warfarin briefly before scheduled dental or surgical procedures. Make sure that everyone involved in your health care is aware that you are taking Warfarin.

Liver function: Liver disease or reduced liver function may cause Warfarin to build up in the body, causing side effects, including severe bleeding. If you have liver problems, discuss with your doctor how Warfarin may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Warfarin, and whether any special monitoring is needed.

Medical conditions and other medications: If you have other medical conditions and are taking medications, discuss with your doctor how Warfarin may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Warfarin, and whether any special monitoring is needed.

Some conditions and medications affect the way warfarin works and may affect the dosing of warfarin. Your doctor will recommend you get regular lab tests done.

Non-steroidal anti-inflammatory medications (NSAIDs): It is recommended that anyone taking NSAIDs such as acetylsalicylic acid (Asa) or Ibuprofen should be closely monitored to ensure that no change in anticoagulation dosage is required. NSAIDs can cause stomach ulcers or bleeding. If you notice any signs of bleeding, such as frequent nosebleeds, unexplained bruising, or black and tarry stools, notify your doctor as soon as possible.

Purple toes syndrome: Purple toes syndrome is a complication of warfarin treatment and consists of a dark, purplish or mottled colour of the toes, usually occurring 3 to 10 weeks (or later) after starting treatment with warfarin. Major features of this syndrome include:

• increasing and decreasing of the colour over time
• pain and tenderness of the toes
• purple colour of bottom surfaces and sides of the toes that turns white under moderate pressure and fades with elevation of the legs

Inform your doctor at once if you notice these symptoms.

Pregnancy: Warfarin should not be used during pregnancy. It may pass to the developing fetus and cause birth defects or death as a result of bleeding. If you become pregnant while taking Warfarin, contact your doctor immediately.

Breast-feeding: It is not known if warfarin passes into breast milk. If you are a breast-feeding mother and are taking Warfarin, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of Warfarin have not been established for children less than 18 years of age. However, the use of warfarin by children is necessary in certain situations.