What does it do?

Warfarin is used to prevent clots forming in your blood. It reduces your risk of having a stroke and stops new clots in your legs or lungs.

Before you start

• Tell your doctor if you have heart, liver, stomach or bleeding problems.
• Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding.

How should you take it?

Take warfarin regularly as directed. Take it with a glass of water at the same time each day. Follow your health professional’s instructions carefully to make sure you take the right dose.
Warfarin comes in two brands in NZ (Marevan® and Coumadin®). Check which brand you have and stick to it.
Warfarin comes in different strengths, with different colours. Most people take the Marevan® brand shown in the picture below. If your tablets look different than usual, check with your pharmacist.

What if you forget a dose?

Take the missed dose if you remember on the same day. If not, skip the dose and carry on as normal. Do not take two doses on the same day. Record the missed doses in your anticoagulant booklet and tell your doctor on your next visit.

Can you take other medicines?

Some medicines available without a prescription may react with warfarin including:

• anti-inflammatories, such as diclofenac (e.g. Voltaren®), ibuprofen (e.g. Nurofen®), or aspirin (e.g. Disprin®, in doses used for pain relief). These can also be found in some cold and flu medicines (e.g. Nurofen Cold and Flu®).
• low-dose aspirin (e.g. Cartia®) - sometimes used with warfarin, check with your doctor.
• orlistat (Xenical®)
• fluconazole (e.g. Diflucan®) or miconazole (e.g. Daktarin Oral Gel®)
• omeprazole (e.g. Losec®)

Tell your pharmacist or doctor about all medicines or treatments that you may be taking, including vitamins (e.g. vitamin K, vitamin E), herbal products (e.g. St John's wort) or recreational drugs.

What side effects might you notice?

Side Effects	Recommended action
Reduced number of blood cells that help your blood to clot - symptoms include: easy or unusual bruising or bleeding Coughing or vomiting of blood, vomit that looks like coffee grounds, nose bleeds Red or dark brown urine, red or black bowel motions Chest pain, trouble breathing Headache, dizziness, changes in vision or speech Skin rash, skin discolouration (blue or purple)	Tell your doctor immediately
Yellow skin or eyes	Tell your doctor
Hair loss or thinning Stomach upset	Tell your doctor if troublesome

If you notice any other effects, discuss them with your doctor or pharmacist.

Other information:

• It is important to tell anyone who gives you medical or dental treatment that you are taking warfarin.
• Tell your doctor if you become unwell or change your diet - your warfarin dose may need to be changed.
• You will need a regular blood test (INR) while taking warfarin to make sure that you are taking the correct dose.
• Alcohol increases the risk of severe bleeding while on warfarin. Alcohol intake should be limited – discuss this with your doctor or pharmacist.