In general, after drinking water in the morning, it is not possible to take blood tests, and most clinical blood tests require a fasting state. In the fasting state, the results of various tests can be more accurate. The most common blood test, if you drink water in the morning, the water will be absorbed into the blood, and the blood will be diluted, which will have a certain interference effect on the test results. Especially for a patient who is close to anemia, if the hemoglobin concentration drops after drinking water, it will lead to the conclusion that the patient is mildly anemic, thus interfering with the test results. In the case of a serological antibody titer test, the dilution of the antibody titer after drinking water may also cause the patient’s antibody titer to drop. Therefore, if you drink water in the morning, you should not draw blood for the test. Of course, if the blood type, blood sedimentation, etc., drinking water in the morning is generally not affected.