Low molecular heparin calcium generally refers to low molecular heparin calcium injection, which has antithrombotic properties and effects. Low molecular heparin calcium injection can be administered by subcutaneous injection to prevent or treat venous thromboembolic disease. It may also be given by intravascular injection for the prevention of blood clot formation during hemodialysis and in combination with aspirin for the treatment of unstable angina. Calcium low molecular heparin may cause bleeding at various sites and small hematomas at the injection site, as well as hypersensitivity reactions such as elevated aminotransferases, abnormal penile erection, and angioedema. During administration, the injection site should be changed to minimize pain and irritation at the injection site, and the medication should be suspended and the doctor informed if severe or progressive discomfort occurs. Low molecular heparin calcium is contraindicated in cases of hemorrhagic cerebrovascular accidents, acute bacterial endocarditis, organic injuries that may cause bleeding (e.g., active peptic ulcers), and active bleeding associated with abnormal hemostasis. Low molecular heparin calcium injection is a prescription drug, patients should follow the doctor’s instructions for medication, not blindly self-administered.