Generally, drinking water is not recommended for fasting blood tests. If you do drink water, a small amount of water usually has little effect, but not a large amount of water. Fasting blood test is usually a venous blood test, a small amount of water, such as a few sips of water, usually does not affect the examination of fasting venous blood, but if a large amount of water, it may cause blood dilution, which in turn affects the accuracy of the test results. Therefore, you can drink a small amount of water, but not a large amount of water for a fasting blood draw. In addition, people who need to undergo fasting blood test should also keep fasting for at least 8 hours, otherwise it will also affect the accuracy of the test results. People who need to undergo fasting blood test should actively cooperate with the operation process of the medical personnel, and if the laboratory results show abnormalities after the fasting blood test, it is recommended to carry out treatment under the guidance of the doctor.