It is not necessary to fast for routine blood tests. Routine blood tests do not require fasting, routine blood tests mainly include red blood cells, white blood cells and white blood cell count, hemoglobin, platelets and so on. When the cause of the disease is unknown, blood tests are helpful in making an auxiliary diagnosis of the disease. In addition, routine blood tests can also be used to observe the effect of treatment, disease recurrence or recovery, and guide the clinical use of drugs. Generally speaking, blood tests such as blood lipids, blood glucose, liver function tests, kidney function tests and other blood-related tests that are more obviously affected by metabolism require fasting because food will have an impact on the test results. It is recommended to consult a professional doctor for precautions and standardized tests before testing.