Self-testing for lactose intolerance can be based on symptoms, but it is easy to misjudge, and it is recommended to go to the hospital for hydrogen breath test, lactose tolerance test and other tests. Lactose intolerant patients will experience abdominal distension, hyperactive bowel sounds, intestinal colic, diarrhea and other symptoms after eating foods containing lactose, and infants and young children will also experience symptoms such as yellow loose stools, acidic odor, and vomiting. If the patient develops uncomfortable symptoms, it is recommended that the patient go to the hospital for examination. Hydrogen breath test can be carried out, patients oral lactulose will be 30 minutes to measure the hydrogen concentration in the breath, 3 hours after the hydrogen concentration increases and greater than 20ppm is lactose intolerance. Patients can also be lactose tolerance test, mainly for blood glucose testing, blood sampling at 0, 60, 120 minutes after oral lactulose, blood glucose value less than 200mg / L can be determined as lactose intolerance. Lactose intolerant patients can be self-tested through their own symptoms, it is recommended that patients appear abdominal distension, bowel sounds and other symptoms in a timely manner to the hospital for examination.