The side effects of Cordyceps sinensis are as follows: First, eating Cordyceps sinensis will affect the growth and development of infants, and taking Cordyceps sinensis during menstruation will aggravate bleeding and cause qi and blood deficiency. Second, the patient has solid inflammation, a real fire, and his body is in a state of high fever. Taking Cordyceps sinensis will further increase his body temperature, which is not good for controlling inflammation and reducing fire. Third, patients with hypertension, stroke and tumor must be cautious when using Cordyceps sinensis, otherwise it will raise blood pressure, induce cerebral hemorrhage and even spread the tumor. Fourth, patients with bleeding must pay attention to taking Cordyceps sinensis, which may increase the amount of bleeding. Fifth, patients with rheumatoid arthritis, taking Cordyceps sinensis will increase inflammation and joint pain.