Diarrhea rids the body of bacteria or toxins in the digestive system. There can be many causes of diarrhea. It may be caused by an allergy, virus or bacteria that attacks the bowel. Bacterial infections of the bowel may need to be treated with drugs. Diseases such as diabetes may cause diarrhea.
Diarrhea is also a side effect of many drugs.
Foods may also cause diarrhea. Milk and dairy products are a common cause of diarrhea in elderly people. The sugar found in milk, called lactose, can't be broken down, resulting in gas, stomach cramps and diarrhea. A complication of diarrhea is dehydration - a lack of water in the body. During bouts of diarrhea, it's important to drink lots of clear liquids.