Anti-coagulant medications are used to treat disorders of clotting or to treat conditions where blood vessels are very narrow and a blood clot would be catastrophic.  Some people are born with disorders of clotting and, at an early age, they form blood clots in various veins.  When tested, they show factors in the blood that promote clotting.  They need to be on anti-coagulant medication for the rest of their lives. Other people who need anti-coagulant medication include people who have developed a blood clot.  The most common type of blood clot is a deep vein thrombosis (DVT) of the lower leg.  It happens when a person is inactive for long periods of time, such as when they are in the hospital or laid up at home for a while.  The risk of this type of blood clot is that pieces of the clot can break off and end up in the lungs causing shortness of breath and low oxygen levels. This is called a pulmonary embolism.  If a large clot breaks off, it results in the clot blocking the venous entry to both lungs, resulting in immediate cardiac arrest and death. Anti-coagulant medication can be given to those who have a risk for DVT or an active DVT or minor pulmonary embolism.  People with narrow coronary arteries or carotid arteries sometimes take anti-coagulant medications to prevent clots.  The arteries have become narrowed due to cholesterol plaques and become so narrow that the blood squeezing through narrowed areas can easily clot.  Anti-coagulants can be given even before any clot has happened.

There are oral and intravenous/subcutaneous anti-coagulant medications.  Most oral medications are used for ambulatory patients at home.  Most of the other anti-coagulant medications are used in a hospital setting. 

Tissue plasminogen activator or TPA is used as a clot-busting drug.  It is used when a person already has a clot that has caused a heart attack, pulmonary embolism or stroke.  It breaks down clots and is used in a hospital setting. TPA must be used within a certain period of time or it will not help the problem.  It carries the risk of severe bleeding.

Heparin is usually used in a hospital setting but subcutaneous heparin is occasionally prescribed for patients at high risk for clots who are in a home setting.  It is both used to treat clots and to prevent them.  It cannot be used in patients who have low platelets.  The risk of being on heparin is that it carries the risk of heavy, uncontrollable bleeding.  It must be given in careful doses so that the blood is not too thick and not too thin.  

Warfarin or Coumadin® is an oral blood thinner used best to prevent blood clots. It is often given after a person has first been on heparin because heparin works immediately and warfarin takes several days to take effect.  Like heparin, the blood must be regularly monitored to make sure the dose is correct.  It is often taken for long periods of time in patients who are at risk of blood clots. Xarelto is an inhibitor of Factor Xa and is a preventative for blood clots.  Unlike heparin and warfarin, it does not require regular monitoring.  It can, however, cause severe bleeding like the others.