Many babies with diarrhea do not get better despite multiple treatments, and their condition lasts for more than 2 weeks or even several months. At the same time, the appetite is poor and weight gain is slow. Parents are very anxious, but do not know what causes it. Usually diarrhea is caused by the following reasons: 1. Acute diarrhea is not completely cured, mostly seen in babies who are not breastfed and are fed with cow’s milk instead. Such babies have less stomach acid and digestive enzyme secretion and weak digestive ability, thus making the normal bacteria in the lower part of the intestine run to the upper part of the intestine, decomposing and fermenting the food eaten, forming corrupt substances that constantly stimulate the intestine, causing diarrhea for a long time. In this regard, under the guidance of a doctor, food therapy can be used for treatment, such as diluted milk, burnt rice soup, sour milk, fish protein powder, carrot soup and apple puree. 2. Long-term use of antibacterial agents kills the normal flora and allows a large number of pathogenic bacteria to multiply. You should immediately stop using antimicrobials and take some drugs that support the growth of normal bacteria, such as lactase, mommy’s love and pefectin, under the guidance of a doctor, so that the intestinal tract can return to its normal state as soon as possible. 3, allergic to the protein in the milk. To immediately stop drinking, try to breastfeed, or feed soy milk powder, rice paste, and add timely departure from the milk food, serious cases need to go to the hospital intravenous input nutrition.