The same is true of larger batteries, but they are less frequently swallowed. Over a 7-year period they followed 2382 cases of swallowed batteries. Hearing aids were the most common source of batteries swallowed. Most kids who swallowed batteries had no problems. Batteries contain powerful alkaline corrosives that can cause severe burns if they leak inside the body.
Different batteries contain different ingredients.
Among the most common are lithium, manganese dioxide, mercuric oxide, silver oxide, and zinc. Of these, lithium and manganese dioxide usually cause the most severe burns. When the mercuric oxide batteries leak and fragment, they can cause mercury intoxication as well as burns. Mercury poisoning creates a wide variety of problems, but often begins with vomiting, bloody diarrhea, and severe abdominal pain. It can proceed to decay of the walls of the intestines, vomiting blood, shock, and death.