The most common cause of diarrhea in babies after adding complementary foods is food allergy. If your baby has diarrhea within 1-2 days after adding a new food, sometimes accompanied by rash, vomiting, respiratory symptoms, etc., and the symptoms disappear within a few days after stopping the food, then basically you can tell that your baby is allergic to such food. If your baby has diarrhea after adding a certain food, immediately stop eating the food that may cause allergy and drink more water to promote the metabolism and excretion of allergic substances; if the diarrhea or other conditions are more serious, you should go to the hospital for medical treatment. Sometimes babies are not allergic to a certain food, but diarrhea occurs even after using it, then you need to consider whether there is improper feeding, mostly seen in the case of too much complementary food, too coarse in nature and unreasonable feeding time, so mothers should pay attention to avoid these three situations when feeding complementary food to their babies. Diarrhea caused by the addition of complementary foods, the emphasis is on prevention. Common substances that cause allergies in babies are milk, eggs, soy, fish, shellfish, peanuts, nuts, etc. So these kinds of supplemental foods or those containing these substances are recommended to be added after the age of 1. It is not recommended to consume compound or complex ingredients to avoid allergies that are difficult to determine the cause. Generally, acute allergies occur within 24 hours, and chronic allergies occur within about 72 hours, so each new food added should be observed for at least 3 days, and only after there is no abnormality, this food can be consumed as a regular food. The amount added starts with a small amount and is increased more slowly after there is no allergic reaction.