Low molecular weight heparin (LMWH) is a type of anticoagulant medication that is commonly used to prevent and treat blood clots. It is derived from unfractionated heparin, a naturally occurring substance found in the body that helps to prevent blood clotting. LMWH has a lower molecular weight than unfractionated heparin, which allows it to be administered subcutaneously and has a more predictable anticoagulant effect. LMWH works by inhibiting the activity of clotting factors in the blood, thereby preventing the formation of blood clots. It is often used in the treatment of conditions such as deep vein thrombosis, pulmonary embolism, and to prevent blood clots in patients who are undergoing surgery or are at risk for developing blood clots. LMWH is generally considered to be safer and more effective than unfractionated heparin, with a lower risk of side effects such as bleeding. However, like all anticoagulant medications, LMWH carries a risk of bleeding and must be carefully monitored by a healthcare provider.