This will then be reduced to two or three times a week, then weekly and eventually monthly or even quarterly for those who are stable and not taking other medications. The risk of bleeding increases in people aged over 65, those with a history of stroke or gastrointestinal bleeding. With aspirin the main complication is gastrointestinal bleeding because of damage to the stomach lining. Low dose aspirin pills are usually given an enteric coating which protects the stomach tissue. One relatively rare warfarin side-effect is skin necrosis, which usually becomes apparent within a week of starting treatment.
Lesions appear on the skin which are due to small clots in the blood vessels under the surface.
Combined treatment with warfarin and aspirin has been recommend in the UK for prevention of heart attacks in people at risk though this may increase the risk of a haemorrhage. Heparin's side effects also include osteoporosis, hair loss and hypersensitivity. Warfarin should be avoided in pregnancy because it crosses the placenta to the baby, though use of heparin in pregnancy is safe. A diet high in vitamin K which is found in leafy green vegetables may also inhibit some of the warfarin effect.