Clexane is an anticoagulant drug used to reduce the risk of blood clots. Blood clots can form in deep veins, typically in the legs (deep vein thrombosis). While these clots might not be immediately life-threatening, they must be treated as soon as possible. A blood clot can detach and travel through the bloodstream (embolism). If it reaches the lungs, it can cause a pulmonary embolism, which can be potentially fatal.
The most common side effects include bruising, tenderness, mild local reactions, pain, hematoma (internal bleeding causing swelling), skin redness, and nodules (small, firm bumps at the injection site). Mild pain or bruising at the injection site is normal. However, redness, pain, warmth, swelling, discoloration of the skin, or discharge from an old injection site, or fever may indicate a skin reaction or infection. If you notice any of these symptoms at a previous injection site, contact your doctor immediately.