The common causes of watery stools in 50-day-old babies include dietary factors, intestinal infections, etc. Treatment includes general treatment and medication. 1. Dietary factors: infants allergic to protein or lactose intolerance can lead to watery stools, breastfeeding mothers should eat a light diet, eat less high-protein foods, and in severe cases, change to hydrolyzed protein milk powder or take lactase, which can improve the symptoms. 2. Intestinal infections: infants with poor intestinal immunity, viral or bacterial infections can have watery stools, oral probiotics such as Bacillus licheniformis, to regulate the intestinal flora, bacterial infections can be given, such as cefixime, cefdinir and so on for treatment. Oral rehydration salts can be given to prevent dehydration. There may be other reasons why babies have watery stools, so it is recommended to go to the hospital in time for a relevant examination to clarify the cause of the disease and then actively treat it. All of the above medications should be used under the guidance of a doctor, avoid self-medication.