Diarrhea is a condition that results in loose, runny stools. Nearly everyone is affected by diarrhea at some point and causes can include food, medication, bacteria or viral infections and stress. While most cases of diarrhea resolve on their own, medical treatment should be sought if the condition persists for more than two days without improvement or is accompanied by severe abdominal pain. Sometimes diarrhea can be a symptom of an underlying more serious problem or untreated medical condition.