Your health questions answered.
Warfarin Anticoagulation Therapy
I was admitted to hospital and given an injection to dissolve a clot I had in my leg. Now I'm home I have to take tablets called warfarin. Will I have to stay on them for long?
In a word, yes. The ability to form a clot - known as coagulation - is an important function of the body. When we cut ourselves we need some mechanism that stops the bleeding, otherwise we risk a prolonged haemorrhage.
However, if this mechanism malfunctions then clots can form, break off and travel to other parts of the body causing problems. If a clot travels to the brain, it can cause a stroke, while one that travels to the heart can cause a heart attack. It's therefore vital that you continue your tablets to prevent another and potentially more serious clot forming.
So how does it work?
Warfarin, the most widely used oral anticoagulant, works by neutralising one of the clotting mechanisms, thinning the blood and preventing clot formation. The injection you were given did the same job but now you have the therapy in oral form.
Why do I need to go for regular blood tests?
Thinning of the blood has to be controlled safely. Too much of the drug and you get uncontrollable bleeding (haemorrhage); too little and clots can form. The amount of anticoagulant medication you need fluctuates and the exact dose is determined by regular blood tests.
The blood test - the international normalised ratio test (INR) - tells your doctor what dose you require.
A friend told me that warfarin was used as rat poison. Is he right?
Some friend. But in fact there is some truth to what he says. Warfarin was used in older forms of rat poisons which caused the unfortunate rodents to bleed to death. Once humans take it in prescribed doses, there shouldn't be any problems. If, however, you develop black motions, blood in your urine, bruise more easily, have gum or nose bleeds or develop unexpected bleeding to minor injuries, contact your doctor immediately. Otherwise, go for your regular blood tests, keep taking the tablets but maybe find a more cheerful friend.