Acute diarrhea is an increased number of stools or looser form than is customary for the patient, lasting less than 2 weeks, and often associated with abdominal symptoms such as cramping, bloating, and gas. Although often mild, acute diarrhea can lead to severe dehydration as a result of large fluid and electrolyte losses. Acute diarrhea is one of the most commonly reported illnesses in the United States.
Acute, watery diarrhea is usually caused by a virus (viral gastroenteritis.) Medications such as antibiotics and drugs that contain magnesium products are also common offenders. Recent dietary changes can also lead to acute diarrhea. These include intake of coffee, tea, colas, dietetic foods, gums or mints that contain poorly absorbable sugars. Acute bloody diarrhea suggests a bacterial cause like Campylobacter, Salmonella or Shigella. Eating contaminated foods such as ground beef or fresh fruit can cause diarrhea due to E.coli 0157:H7. Diarrhea associated with recent antibiotic use suggests an infection with Clostridium difficile.
Most episodes of acute diarrhea resolve quickly and without antibiotic therapy with simple dietary modifications. See a doctor if you feel ill, have bloody diarrhea, severe abdominal pain or diarrhea lasting more than 48 hours.
In patients with mild acute diarrhea, no laboratory evaluation is needed because the illness generally resolves quickly. Your doctor may perform stool cultures or parasite exams if your diarrhea is severe or bloody or if you traveled to an area where infections are common.
It is important to take plenty of fluid and salt to avoid dehydration. Milk and dairy products should be avoided for 24 to 48 hours as they can make diarrhea worse. Initial dietary choices should begin with soups and broth. This should be followed by a low residue diet (low fiber) until the diarrhea resolves. Probiotics may be helpful.
Anti-diarrheal drug therapy can help control severe symptoms, and includes bismuth subsalicylate (Pepto-Bismol, Kaopectate) and anti-motility agents such as loperamide (Imodium). These, however, should be avoided in people with high fever or bloody diarrhea.
An antibiotic is usually necessary for patients with a high fever, dysentery, or moderate to severe traveler's diarrhea.
If diarrhea lasts more than two weeks, it is called chronic diarrhea.
Chronic Bloody Diarrhea
Chronic bloody diarrhea is most likely due to Inflammatory Bowel Disease (IBD). These include Ulcerative Colitis or Crohn’s Disease. Other less common causes include ischemia (decreased blood flow) of the colon, infections, radiation therapy and colon cancer or polyps.
Chronic Oily or Fatty Diarrhea
Maldigestion or malabsorption syndromes are the cause of fatty stools. The stools may also be greasy or very bad smelling. Chronic pancreatitis is a cause of pancreatic insufficiency, which leads to maldigestion and fatty stools. Alcohol abuse is a common cause of chronic pancreatitis in the United States. Other causes of chronic pancreatitis include cystic fibrosis, hereditary pancreatitis, and trauma to the pancreas and pancreatic cancer.
Biliary tract obstruction, cholestatic liver disease, and bacterial overgrowth can also lead to maldigestion problems. Gluten sensitive enteropathy (celiac disease, celiac sprue) is the most common small bowel disease causing fat malabsorption. Additional common causes of malabsorption in the United States are other small bowel mucosal diseases or surgical resection of the small bowel. Whipple’s disease, tropical sprue and Zollinger-Ellison syndrome are very uncommon conditions that can lead to malabsorption.
Chronic Watery Diarrhea
There are many causes of watery diarrhea, including carbohydrate malabsorption such as lactose, sorbitol, and fructose intolerance, intestinal infections or Irritable Bowel Syndrome. Certain medications such as NSAIDs, antacids, antihypertensives, antibiotics and antiarrhythmics can cause diarrhea in some people.
Symptoms of abdominal bloating and excessive gas after consuming dairy products suggest lactose intolerance. This condition is more common in African-Americans and Asian Americans. Certain soft drinks, juices, dried fruits and gums contain sorbitol and fructose, which can lead to watery diarrhea in people with sorbitol and fructose intolerance.
Intestinal infections such as giardiasis, opportunistic infections in someone with HIV can cause chronic watery diarrhea. Diabetes mellitus may be associated with diarrhea due to nerve damage and bacterial overgrowth; this occurs mainly in patients with long-standing, poorly controlled diabetes.
Irritable Bowel Syndrome (IBS) is a condition often associated with frequent stools, alteration in bowel habits, and abdominal pain. These symptoms are key features of this syndrome, though many with IBS have constipation rather than diarrhea. Emotional or physiologic distress can worsen IBS symptoms. IBS is recognized as a motility disorder where no anatomic or organic diseases are found to account for the symptoms.
Your doctor will want to further assess etiologic factors or complications of diarrhea by obtaining several tests. These include blood tests. A stool sample may help define the type of diarrhea. The presence of fat, occult blood and white blood cells will help determine if a watery, inflammatory, or fatty diarrhea is present. A bacterial culture and ova/parasite studies of a stool specimen will also help determine if an infectious etiology is present.
Endoscopic examination of the colon with colonoscopy is more specific than radiographic studies in detecting the etiology of chronic diarrhea, as this allows direct examination of the bowel mucosa and the ability to obtain biopsies for microscopic evaluation as is upper endoscopy (EGD) for evaluation of the upper GI tract. Small bowel video capsule endoscopy is sometimes used to examine the lining of the entire small intestine.
The treatment depends on the etiology of the chronic diarrhea. Often, empiric treatment can be provided for symptomatic relief.