Constant or chronic diarrhea is diarrhea lasting for more than two weeks, according to the Centers for Disease Control and Prevention (CDC). For a healthy person, this is a mere annoyance. For someone with a weak immune system, however, it can be a sign of a life-threatening illness.
Bacteria
Various bacteria and parasites found in contaminated water and food can infect the body, resulting in diarrhea. Most of the time, the infections these parasites cause go away on their own. However, as Jackson Siegelbaum Gastroenterology explains, some bacterial infections, like salmonella, require medical attention.
Parasites such as amoeba and giardia attack the intestines. These parasites are found in wild animals and in contaminated streams and well water.
Because a number of infections can occur in the intestinal tract of people with AIDS, they must be closely monitored if they experience chronic diarrhea.
Digestive Disorders
According to the Mayo Clinic, certain digestive disorders such as Crohn's disease, ulcerative colitis, irritable bowel syndrome and celiac disease are all culprits of chronic diarrhea. These conditions are causes of constant diarrhea not caused by infection. They all require careful medical attention and treatment, however.
Lactose Intolerance
One of the most common food intolerances is lactose intolerance, a condition in which a person is unable to tolerate milk or milk products, with the exception of yogurt. Jackson Siegelbaum Gastroenterology explains that when lactose is ingested in even the smallest amounts, diarrhea can result.
Medications
A variety of medications can cause diarrhea, the most common being antibiotics. When taken, the antibiotic destroys both good and bad bacteria, unable to differentiate between the two. This upsets the natural balance in the intestines, resulting in diarrhea. According to Jackson Siegelbaum Gastroenterology, diarrhea can begin up to one month after taking the antibiotics.
