Most people experience constipation or diarrhea from time to time. Although it can be uncomfortable, the majority of instances result from benign sources rather than significant disease. Constipation is defined as having a bowel movement fewer than three times a week, while diarrhea is defined as having a bowel movement that is loose and watery more than three times a day. People suffering from diarrhea can pass more than a quart of stool a day, causing dehydration.
Bacteria and Parasites
According to KidsHealth.org some of the more common bacteria that cause diarrhea are E. coli, Salmonella enteritidis, Campylobacter and Shigella. All these bacterial infections of the intestines are easily spread. The first three are common in contaminated foods, such as raw or undercooked beef and chicken or fruit. Parasites that cause diarrhea include Giardia and Cryptosporidium. Both are found in contaminated water supplies. Giardia is resistant to chlorinated treatments and is found in pools and water parks, while Cryptosporidium is also found in drinking water and responsible for watery diarrhea that can last for up to two weeks, notes KidsHealth.org.
Viruses
Viruses that affect the gastrointestinal tract can be passed quickly through home, school or daycare environments because they are highly infectious. Symptoms usually only last a few days but can cause severe dehydration in infants and young children. These viruses include rotavirus, enteroviruses, Norwalk virus and cytomegalovirus.
Functional Disorders
A functional bowel disorder is a disease distinguished by chronic abdominal complaints without a structural or biochemical cause that explains symptoms. One such underlying medical condition is irritable bowel syndrome. It is characterized by cramping, bloating, constipation and diarrhea.
Food
Waste production from food intake will sometimes be affected by the types of food eaten. According to physicians at the Mayo Clinic, constipation can be the result of inadequate amounts of fiber in the food. Fiber will help to retain fluids that keep the stool soft and easy to pass. However, food intolerances can also cause diarrhea. According to the National Digestive Diseases Information Clearinghouse, some people are unable to digest components of some foods, such as the sugars found in milk or artificial sweeteners. This inability leads to diarrhea.
Intestinal Slowing
The waste products from food move through the intestines through contractions of the intestinal wall in a squeezing motion. This process can be slowed by a number of lifestyle choices, causing constipation. According to FamilyDoctor.org, these choices include not drinking enough fluids, lack of exercise, not going to the bathroom when the urge is felt and regularly using laxatives.
Medications
Reactions to medications can cause an increased motility in the intestines or a decrease in the natural bacteria. According to the National Digestive Diseases Information Clearinghouse, medications can cause diarrhea in two ways. Antibiotics will kill the "good" bacteria in the lower intestines, often resulting in diarrhea until the natural balance can be re-established. Blood pressure medications, cancer drugs and antacids that contain magnesium are also categories of medications that can cause diarrhea.
