Diarrhea is classified as acute or chronic. Acute diarrhea is diarrhea that lasts less than 2 weeks and chronic lasts longer than 2 weeks. Most causes of diarrhea last 2-3 days. This chapter will look at acute diarrhea as chronic diarrhea could take up a whole book.

• Viral infections present with diarrhea that lasts 2-3 days with no blood in the stool.
• Eating foods that bother the stomach and intestines can cause diarrhea. Sometimes keeping a food diary/bowel movement diarrhea can help you determine which foods cause diarrhea.
• Parasites such as Giardia can present with loss of appetite, abdominal bloating and cramping and foul smelling stool.
• Some medications that cause diarrhea include laxatives, medications for heartburn, antibiotics, magnesium containing products and alcohol.
• Bacterial infections that commonly cause diarrhea include: Clostridium difficile (often occurs after taking antibiotics), Campylobacter and Escherichia coli (common cause of food poisoning). These infections present with fever, blood in the stool and white blood cells noticed in the stool by the doctor.
• Food poisoning can result in nausea, vomiting and diarrhea.
• Lactose intolerance often leads to chronic diarrhea (but should be considered in acute diarrhea). Lactose intolerance is associated with gas, bloating and explosive diarrhea.
• Breastfeeding can cause loose stools in infants.
• Traveler's diarrhea is common in those who go to Asia, Africa, Central or South America and the Middle East. It presents with diarrhea, nausea, vomiting, slight fever and abdominal cramping.
• Partial bowel obstruction can cause diarrhea.
• Constipation results in a hard stool that liquid stool can work its way around resulting in diarrhea.

In diarrhea, the first step is to replace lost fluids and avoid dehydration.

The young child with moderate diarrhea should try to get 50-100 ml (this is approximately 2-3 ounces) of fluid per kilogram over 4 hours. After each loose stool the person should consume 10 ml of fluid per kilogram. It may require small intakes of fluid at first. Encourage small amounts and advance as tolerated. For example, start with one teaspoon every five minutes and if there is no more diarrhea or vomiting increase to 2 teaspoons every 5 minutes after 15-30 minutes.

For example, the first step in determining the recommended fluid intake for a 65-pound child with diarrhea is calculating his weight in kilograms. It can be calculated by dividing his weight in pounds by 2.2. This yields a weight in kilograms of almost 30. This child would need to consume 60 to 90 ounces of fluid over a four-hour period. This equates to 15 to 22 ounces per hour. For every loose stool the child should consume another 300 ml of fluid or 10 ounces.

The adult with moderate diarrhea should consume 2-4 liters of fluid over four hours and drink 15-20 ml of fluid per kg for each loose stool.

In those with mild diarrhea they should consume their regular diet and increase fluid intake. The person should avoid fatty or spicy foods and those high in simple sugars. Caffeine and alcohol should be avoided.

Start an age appropriate diet as soon as you can. Typically the diet should be eaten after there is no more vomiting and you are rehydrated. Formula is OK to use in the young child.

When the diarrhea is moderate and the person is bothered by symptoms, the use of OTC anti-diarrhea medication is not unreasonable. It should be used according to the label. The two OTC products are loperamide and bismuth subsalicylate. Natural Product