Children are prone to diarrhea when fall arrives. If you find a change in the stool pattern of your infant or child, you should keep a stool specimen in a plastic box or plastic wrap and send it to the hospital for examination as soon as possible (not more than two hours). In addition to routine stool tests + occult blood, rotavirus, adenovirus and norovirus antigens should also be tested in the fall and winter. Viral gastroenteritis with rotavirus as the main cause appears in autumn and winter, starting with fever followed by vomiting and diarrhea (watery stools), so pay attention to the prevention and control of dehydration. If the stool is thin and the stool routine + pathogenic antigen test is negative, you can consider whether it is caused by changes in food, and also whether it is caused by changes in the weather? Observe the general changes of the child, whether there is any loss of appetite, weight loss, sleep disturbance and so on. If the analysis is not clear, you can consult your doctor and seek medical advice. Do not take anti-diarrheal and anti-inflammatory drugs easily to avoid masking the condition.