If your one-year-old baby has diarrhea, if the symptoms are obvious, you can take some symptomatic medications orally, such as the most commonly used probiotics, and the more effective probiotics easily available on the market are generally YIWU, Pefikang, Siliancon, Jin Shuangqi, and Mamia, etc. If the stool is very thin and watery, you need to take oral zinc, such as zinc gluconate oral solution or zinc lysine gluconate. If there is no infection in the routine stool examination and the stool is very dilute and watery, you can use a combination of montelukast. The course of probiotics and zinc is about 10-14 days, and the dosage of montelukast should be gradually reduced to stop when the stool turns from thin to thick, or when the stool is slightly formed. If the diarrhea is severe, especially if it is accompanied by fever and the baby is in poor spirits, a special infection needs to be considered. Stool routine and other related tests should be done, and anti-infective and other treatments should be administered as appropriate according to the clinical diagnosis and laboratory tests.