Getting to the Bottom of Diarrhea

Whether you call it the runs or Montezuma’s revenge, diarrhea is a common experience for everyone like getting caught in the rain. While there’s many colorful ways to describe diarrhea, it’s one of the most widespread illnesses. There are nearly 180 million cases of acute diarrhea every year, according to a review in the New England Journal of Medicine.

Loose, watery bowel movements affect everyone from time to time — and usually disappear on their own. Most diarrhea is not managed by doctors and is usually handled at home, says Dr. Mark Riddle, professor of internal medicine and associate dean for clinical research at the University of Nevada School of Medicine in Reno, Nevada. “The main consequences of diarrhea are usually absenteeism or presenteeism due to short-term illness.”

“Diarrhea that is ongoing and associated with significant abdominal pain and fevers, or waking a person up from sleep, is more serious and should prompt a call or visit to the doctor,” says Dr. Colleen Kelly, associate professor of medicine at the Warren Alpert Medical School at Brown University in Providence, Rhode Island.

[READ: What Is Normal Poop?]

Causes of Diarrhea

The vast majority of acute diarrhea is due to infection with viruses and bacteria, says Dr. Brooks Cash, chief of gastroenterology at UTHealth and professor of medicine at the McGovern Medical School in Houston. “Most of these infections only require supportive care in the form of antidiarrheals and adequate fluid intake. Occasionally acute diarrhea does need to be treated with antibiotics and possibly even hospitalization.”

The main causes of diarrhea include:

Chronic conditions. Intestinal disorders (colitis, Crohn’s disease, irritable bowel syndrome), disorders of the pancreas (chronic pancreatitis, pancreatic enzyme deficiencies) and hereditary disorders (cystic fibrosis, enzyme deficiencies) can cause chronic diarrhea.

COVID-19. One of the major symptoms of getting the COVID-19 virus is diarrhea. Typically, diarrhea lasts for about two to three days among those infected with COVID-19, but it can last longer in some cases.

Food poisoning. After eating or drinking contaminated food or water, food poisoning can come on quickly or take hours to develop. Food poisoning doesn’t just happen at restaurants — the spinach and lettuce you buy at the grocery store could be the source of your next diarrhea attack. Many vegetables are imported from developing countries that could be contaminated by E. coli or salmonella, both bacteria that cause diarrhea. Always properly wash produce to avoid any diarrhea-producing viruses upsetting your digestive system. Also be careful to always consume clean water. Be especially cautious after natural disasters when safe drinking water may be in short supply.

Infections. Major stomach bugs that cause serious diarrhea include parasitic infections such as cryptosporidiosis and giardia, which exist in rivers and lakes can cause prolonged diarrhea. There’s also viral infections from hepatitis A, norovirus or rotavirus, and bacterial infections from E. coli, shigella, salmonella, vibrio or leptospirosis. These infections can lead to serious health problems for young and old people and those who become severely dehydrated from diarrhea.

Lactose intolerance. The inability to break down lactose in milk products can lead to several gastrointestinal symptoms like diarrhea. The risk of lactose intolerance can increase as you get older because levels of the enzyme that helps digest lactose drop as you age.

Medical treatments. Diarrhea is a known side effect associated with many medications. These may include: antibiotics, antidepressants, proton pump inhibitors and cancer treatment drugs. Over-the-counter medicines like antacids taken to treat heartburn can cause diarrhea. When they do, it can be because they contain high amounts of magnesium or calcium, which can contribute to diarrhea. Radiation therapy to your stomach area can also cause loose stools.

Runner’s diarrhea. This occurs mostly among long-distance runners and can happen during or following a run. The cause of runner’s diarrhea is unclear, but food and nutrients move more rapidly through the digestive system of runners and athletes in general.

Traveler’s diarrhea. In addition to developing diarrhea at home, millions of people in the U.S. travel overseas. According to a study published in JAMA, diarrhea is the most common illness that affects travelers to developing nations. Better personal hygiene practices has lowered the risk of traveler’s diarrhea from 20% to between 8% and 20%, according to the 2015 study.

[READ: Remedies for a Stomach Ache.]

Symptoms of Diarrhea

Diarrhea is often coupled with other unpleasant symptoms that usually vanish within a few days. Milder diarrhea symptoms can be a nuisance or cause patients to worry about needing to be near a bathroom, says Kelly. “More moderate symptoms often limit a patient’s activities; some will avoid doing things like running or going out to eat, for fear of having an episode. Severe diarrheal symptoms can result in dehydration or electrolyte abnormalities.”

Other related symptoms with diarrhea include:


— Blood in the stool.

— Flatulence.

— Fever.

— Passage of bloody stools.

— Stomach pain and cramp.

— Vomiting.

— Urgent bowel movements.

Health Complications

While most cases of diarrhea are mild and resolve on their own within a few days, there are situations where diarrhea can lead to serious health problems.

“Because diarrhea is such a common condition, we do see a substantial number of patients present with dehydration due to diarrhea,” says Cash. “This scenario is most common at the extremes of age such as infants and the elderly, and is typically a gradual process over several days whereby fluid and nutrients or electrolyte intake is exceeded by their loss in the stool.”

Dehydration. Because you lose water during a diarrhea episode, dehydration is the most common complication. Signs of dehydration include dry mouth, dry skin, weakness and feeling lightheaded, little or no urination, and of course feeling very thirsty. Dehydration is particularly dangerous in children, older adults and those with weakened immune systems. Individuals with chronic medical conditions such as kidney problems and cardiopulmonary disease are also at risk of dehydration. Becoming rehydrated again is the primary goal to combat dehydration.

Electrolyte imbalance. When your body loses water it’s also losing electrolytes, including sodium, chloride, calcium, phosphate, potassium and magnesium. Each electrolyte plays a specific function to keep your body working well. Chloride, for instance, is essential to proper digestion.

How to Prevent Diarrhea

There are several steps to avoid diarrhea with the help of modern vaccines,
proper hygiene like hand-washing and appropriate food handling.

Hand-washing. Diarrhea is often spread from person to person through contaminated water or food, so hand-washing is one of the main ways to limit the risk of spreading diarrhea.

Food handling. Most foodborne infections occur from improper food-handling or cooking in the home. Improving the preparation of food will lower your chance of food poisoning and protect yourself and loved ones.

Diet and nutrition. Dairy products and foods containing gluten may cause diarrhea, especially those who are lactose intolerant or gluten intolerant. Avoid spicy foods like chili peppers because your body may not be used to spicy stuff and can trigger diarrhea.

Vaccines. To help avoid becoming infected with diarrhea-causing rotavirus, the Centers for Disease Control and Prevention recommends that infants receive the rotavirus vaccine before an infant is 15 weeks old and complete all oral doses by 8 months old.

[READ: Best Over-the-Counter Products for Digestive Problems.]

Treatment and Care

Most episodes of diarrhea can be treated at home with rest and plenty of fluids. Avoiding eating a drinking for a few hours to let your stomach settle. “Small sips of water or noncaffeinated beverages can help keep you hydrated,” says Riddle. “You want to take in fluids in some way to make sure you are urinating and that your urine is not dark.”

Depending on the cause of diarrhea, these treatment options may be used to clear an infection or resolve symptoms:

Antibiotics. Diarrhea caused by an infection sometimes can be treated with antibiotics or other drugs. Ciprofloxacin is the typical treatment of traveler’s diarrhea except when patients are in South or Southeast Asia, where azithromycin is preferred.

Antidiarrheals. These products that are household names like Imodium and Pepto-Bismol allow the body to start absorbing fluids and salts again so bowel movements are less watery.

Anti-gas medicines. To combat diarrhea-related symptoms like bloating, stomach pain and excess gas, anti-gas medications like Gas-X, Mylanta and Phazyme often provide relief.

Rehydration solutions. Products such as Pedialyte for children, Gastrolyte or similar commercially available solutions containing appropriate amounts of sodium, potassium and glucose should be used for rehydration at any time. In severe cases, when someone is hospitalized, appropriate intravenous fluids may be used.

For infants and toddlers suffering from diarrhea, parents need to ensure increased fluid intake. “It is critically important to maintain hydration in children with diarrhea as they can become dehydrated very quickly,” says Cash. “This is best accomplished with electrolyte and glucose containing rehydration solutions.”

More from U.S. News

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