Patients who experience dizziness after blood tests and blood draws are considered to have bloodsickness reaction, and the reasons for its formation are mainly the following: 1. Mainly related to psychological factors, patients in the process of blood draws may produce fear and nervousness, which may easily lead to vagal excitation and hyperactivity, which will lead to expansion of the blood vessels of the visceral organs and reflexively cause slowing of the heart rate of the patient and weakness of the cardiac contraction, which will cause insufficient blood supply to the patient’s brain, resulting in vasovagal syncope; 2. The patient’s brain blood supply is insufficient, resulting in vasovagal syncope; 2, to consider the environmental factors, such as crowded, noisy environment will invariably increase the patient’s psychological pressure, it is easier to make the patient appear adverse psychological emotions; 3, with the patient’s physical condition, for example, the patient fatigue, long time fasting, it is easier to cause blood fainting, fainting needles happen.