Drinking a sip of water can be tested for blood, requiring the blood test to be done on an empty stomach, that is, in the morning after waking up, so that for many indicators more accurate. But a sip of water will not have much effect on the testing of indicators, basically. Blood tests include routine blood, liver and kidney function, electrolytes, blood sugar, blood lipids, and even thyroid function, glycosylated hemoglobin or tumor indicators. If the patient eats after eating, that is, after eating a liquid or semi-liquid food, or even rice or bread, it may have an effect on liver function, blood lipids, blood glucose and other tests. However, it will not have any effect on the blood routine, tumor index and hepatitis B five tests.