While rarely serious when treated properly, diarrhea can send your toddler to the hospital if he becomes dehydrated, so your first concern should be giving him enough liquids. If your toddler isn't also vomiting, it should be fairly easy to give him extra water to drink. If he can't keep liquids down, though, or if his diarrhea is severe (a watery bowel movement every two hours or more), call his doctor, who may suggest a pediatric electrolyte solution, like Pedialyte, ReVital, or a generic brand. These solutions are available in drugstores and come in flavors that most toddlers will readily drink if they're dehydrated.
Avoid sweetened fluids like sodas (including ginger ale), athletic drinks (like Gatorade), Jell-O, sugar water, and undiluted fruit juices. All of these contain sugar that will draw water into the intestine and make the diarrhea worse. Also don't use anti-diarrhea medication unless the doctor prescribes it.
Doctors now advise continuing to feed solid foods to a child with diarrhea. While there's nothing wrong with feeding your toddler the classic BRAT diet (bananas, rice, applesauce, and dry toast), the AAP says any foods made up of complex carbohydrates, such as rice, wheat, potatoes, bread, and cereal, as well as lean meats, yogurt, fruits, and vegetables, are safe to eat. (If your toddler temporarily refuses to eat, don't worry. As long as he stays hydrated his appetite should return in a day or two.)
Studies have shown that live bacterial cultures, found in yogurt, are a safe and effective way to cut down on the amount and duration of diarrhea. It's an easy way to treat the problem, especially if your toddler loves the taste of yogurt. Just be sure to buy yogurt with lactobacillus, or live cultures.
If your toddler is uncomfortable during a bout of diarrhea, try to cuddle and comfort him as much as possible and keep his bottom dry. Use care, tenderness, and plenty of diaper cream when changing him, since it's easy for your toddler's bottom to become red and irritated from the loose stools.