1. Bleeding is the most common and may occur anywhere.

　　2. Common allergic reactions such as chills, fever and urticaria.

　　3. Long-term medication can cause hair loss and transient reversible alopecia, osteoporosis and spontaneous fractures.

　　4. Local stimulation, erythema, slight headache, hematoma, ulcer and so on can be seen locally after injection. Intramuscular injection is more serious, so intramuscular injection is not suitable.

　　5. Transient thrombocytopenia is still present. Heparin-induced thrombocytopenia (HIT) is due to the binding of the heparin-platelet factor 4 antibody complex to the platelet factor 4 receptor. Can activate platelet aggregation, cause arteriole embolism. Although rare, it can be fatal. Stop heparin immediately if HIT occurs.