Heparin is available as heparin sodium injection, heparin sodium cream, and low molecular heparin sodium injection, etc. Precautions for the use of heparin vary according to the dosage form. 1. Heparin sodium injection: attention should be paid to the measurement of clotting time; late pregnancy and postpartum application has increased the risk of bleeding, so pregnant and lactating women should be cautious; children and the elderly should be cautious. 2. Heparin sodium cream: it should not be used for a large area and for a long time; avoid contact with other mucous membranes such as eyes and mouth and nose; allergic people should be cautious; pregnant and lactating women should be cautious. 3. Low molecular heparin sodium injection: Because intramuscular injection can lead to local hematoma, so it can not be intramuscular injection; bleeding tendency, such as gastroduodenal ulcers, etc., has been orally anticoagulant drugs and other cases should be used with caution; because this drug can induce thrombocytopenia, so platelet count should be examined prior to treatment; renal impairment should be used with caution; pregnant women and lactating mothers, the elderly and children should be cautious about the use of the above drugs. The application of the above drugs should be carried out under the guidance of a physician, and should not be used on its own.