Leeches have the efficacy of breaking blood circulation, eliminating blood stasis and eliminating symptoms. The time for leeches to take effect depends on the patient’s specific condition and cannot be generalized. According to the Chinese Pharmacopoeia, leeches are salty, bitter, neutral, slightly toxic, and belong to the liver meridian. It has the effect of promoting blood circulation and opening up the menstruation, eliminating blood stasis and eliminating symptoms, and is suitable for treating blood stasis and menstrual occlusion, mass in the abdomen, fixed and immovable mass in the abdomen, lumps in the abdomen, hemiplegia, bruises, stagnation of blood in the heart and abdominal pain, and so on. Leeches are strong in promoting blood circulation and menstruation, and are slightly toxic, so they are forbidden for pregnant women and people with excessive menstruation. Leeches are often used in combination with other medicines, for different diseases, leeches have different onset of action time, and the patient’s disease, the extent of the disease and the patient’s physical condition are not the same, so leeches will have different onset of action and stopping time. Leeches should be taken under the guidance of a professional physician, and patients need to strictly abide by the doctor’s instructions, standardize the use of medication, and should not take medication without authorization.