Function

• Anticoagulants work by reducing the blood's capability to form clots. Most anticoagulants prevent platelets from sticking together as easily as they normally do, thus inhibiting the formation of blood clots. Blood clots not only cause heart attacks and strokes but serve an important purpose in the body--stopping blood loss. Most side effects associated with anticoagulants are a result of excess bleeding.
  
  

Effects

• The most common side effects associated with anticoagulant therapy are itching, rashes, easy bruising, increased bleeding from injuries and purplish spots on the skin. Purplish skin spots are caused by small amounts of bleeding under the skin. Bruising tends to be more severe when taking anticoagulants, and bleeding from wounds can be difficult to stop.
  
  

Significance

• Side effects caused by taking anticoagulants can be dangerous. This is especially true if your gastrointestinal system begins to bleed while you are on anticoagulant therapy. For example, a stomach ulcer that would normally bleed only tiny amounts may begin to bleed heavily, causing you to vomit up a material that resembles coffee grounds. This material is actually partially digested blood and indicates potentially dangerous blood loss. Other side effects that require prompt medical attention include black, tarry stool, blood in the urine and uncontrollable bleeding from an injury.
  
  

Considerations

• The benefits of anticoagulant therapy usually outweigh the risks associated with the drugs. However, in some situations, the drugs can be more dangerous. You should not usually take anticoagulants if you have an active ulcer, if you are pregnant or plan to become pregnant, or if you are breastfeeding an infant. Before having surgery or significant dental work done, it is important to stop taking anticoagulants for a period of time. Ask your doctor for advice about when to stop taking and resume taking your anticoagulants if you need an operation or dental procedures.
  
  

Warning

• Some types of anticoagulants are associated with a potentially life-threatening condition called TTP, or thrombotic thrombocytopenic purpura. The risk of TTP is very low with normal use of anticoagulants, but it is important to be aware of the symptoms of this condition. TTP sometimes occurs as soon as a few weeks after beginning anticoagulant therapy, and side effects include fever, weakness and confusion. If you experience these symptoms while taking anticoagulants, seek medical care immediately.