Common Questions & Answers

What are the main symptoms of diarrhea?

The main symptom of diarrhea is passing loose, watery stool three or more times a day. Other symptoms can include abdominal pain, urgency to go to the bathroom, nausea, bloating, anal irritation, and loss of control of bowel movements.

What additional symptoms may indicate an infection causing diarrhea?

Infections causing diarrhea may also present with symptoms such as bloody stools, vomiting, fever and chills, and light-headedness and dizziness.

What are the signs of dehydration and malabsorption associated with diarrhea?

Signs of dehydration include extreme thirst, decreased urination, dark-colored urine, dry mouth, fatigue, sunken eyes or cheeks, feeling faint, and decreased skin turgor. Signs of malabsorption include bloating, gas, abdominal pain, nausea, vomiting, changes in appetite, weight loss, and fatty stools.

Is diarrhea a symptom of COVID-19?

Yes, diarrhea, along with nausea and vomiting, can be a symptom of COVID-19. It can also be an ongoing issue for those with long COVID.

What tests may be done to diagnose the cause of diarrhea?

Tests for diarrhea may include stool tests to check for infections, blood tests to identify signs of infection or inflammation, colonoscopy or sigmoidoscopy to examine the colon, hydrogen breath test to diagnose lactose intolerance, and fasting tests to determine food intolerances or allergies.

Diarrhea can lead to dehydration and malabsorption, each of which have their own symptoms.

Signs of dehydration include: extreme thirst, urinating less frequently than normal, dark-colored urine, dry mouth, fatigue, sunken eyes or cheeks, feeling faint, and a decreased skin turgor (when the skin is pinched and released, it does not flatten back to normal right away). In children, additional signs of dehydration can include a lack of energy and the absence of tears while crying.

Symptoms of malabsorption include bloating, gas, abdominal pain, nausea, vomiting, changes in appetite, weight loss, and fatty stools.

COVID-19 and Diarrhea

Diarrhea, along with other gastrointestinal issues like nausea and vomiting, is a symptom of COVID-19.

In some people, digestive problems are the first sign of the illness. One study, for example, found that about 20 percent of people experienced diarrhea as their first symptom of COVID-19.

Other research suggests having diarrhea with COVID-19 is associated with an increased risk of severe illness.

Ongoing diarrhea is also an issue for many people who have long COVID. Research has found loose, watery stools, as well as other digestive issues, like nausea, acid reflux, and loss of appetite, are common in patients three months after being discharged from the hospital due to COVID-19.

Scientists are still working to better understand the relationship between COVID-19 and gastrointestinal symptoms.

Tests for Diarrhea

Most diarrhea goes away on its own in a few days. When diarrhea lasts for longer, tests are needed to find out what’s causing it so proper treatment can be administered.

A visit to the doctor for diarrhea will consist of a physical examination and a full medical history, including a review of your medication. A physician will also carefully feel your abdomen and may perform a rectal exam.

Additionally, testing for acute diarrhea may include:

Stool Test This might be recommended to determine whether you have a bacteria or a parasite infection. A healthcare professional will give you containers for catching and storing your stool samples, as well as instructions on where to send or take the containers for analysis.
Blood Test A complete blood count can show signs of infection, anemia, inflammation, or imbalances of electrolytes, to help determine the cause of your diarrhea.

If diarrhea persists, or if there are worrisome signs like bleeding, your doctor may order other tests, which include:

Colonoscopy or Sigmoidoscopy These are both tests involving a lighted tube with a camera. A colonoscopy involves following a special diet the day before the exam, typically with no solid foods and usually not eating or drinking anything after midnight the night before the exam. You will also need to take a laxative in either pill or liquid form or use an enema kit to empty your colon. During the procedure, for which you are sedated, the tube is inserted into the rectum and the camera gives the doctor a view of the inside of the entire colon to check for abnormalities.
A sigmoidoscopy is a similar procedure but looks at the rectum and lower portion of the colon only.
Hydrogen Breath Test This test is used to diagnose lactose intolerance by measuring the amount of hydrogen in your breath. When someone is lactose intolerant, undigested lactose produces high levels of hydrogen in the breath. The test involves drinking a beverage with a known amount of lactose and then breathing into a balloon-type container to measure breath hydrogen levels. A high level of hydrogen will lead to a diagnosis of lactose intolerance.
Fasting Test This will help determine if a food intolerance or allergy is the cause of your diarrhea. Your physician may ask you to avoid certain foods, including dairy, wheat, carbohydrates, or other ingredients in an effort to see if your symptoms of diarrhea respond to those diet changes.

When to See Your Doctor

While occasional bouts of diarrhea are common and not cause for concern, diarrhea can become dangerous if it leads to severe dehydration. It can also signal an infection or a more serious health issue.

Visit your doctor right away if you experience any of the following symptoms:

Diarrhea that lasts more than two days
Diarrhea accompanied by a fever of 102 degrees F or higher
Six or more loose stools in 24 hours
Severe, unbearable pain in the abdomen or rectum
Bloody stools or stools that are black and tarry or contain pus
Diarrhea accompanied by frequent vomiting
Signs of dehydration

Infants, toddlers, and young children should be taken to the doctor if they have any of these symptoms or diarrhea lasting more than 24 hours.

Older adults and people with compromised immune systems should also seek medical care if they have diarrhea.

Editorial Sources and Fact-Checking

Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.

Sources

Symptoms & Causes of Diarrhea. National Institute of Diabetes and Digestive and Kidney Diseases.
Diarrhea. Mayo Clinic.
Malabsorption. Cleveland Clinic.
Unusual COVID-19 Symptoms: What Are They. Mayo Clinic.
Digestive Symptoms in COVID-19 Patients With Mild Disease Severity: Clinical Presentation, Stool Viral RNA Testing, and Outcomes. American Journal of Gastroenterology.
Diarrhea Is Associated With Increased Severity of Disease in COVID-19: Systemic Review and Metaanalysis. SN Comprehensive Clinical Medicine.
COVID Lon Haulers: Gastrointestinal Symptoms. Harvard University.
Colonoscopy. Mayo Clinic.

Resources

Symptoms & Causes of Diarrhea. National Institute of Diabetes and Digestive and Kidney Diseases. November 2016.
Diarrhea. Mayo Clinic. August 18, 2021.
Malabsorption. Cleveland Clinic. June 4, 2022.
Unusual COVID-19 Symptoms: What Are They? Mayo Clinic. February 11, 2022.
Han C, Duan C, Zhang S, et al. Digestive Symptoms in COVID-19 Patients With Mild Disease Severity: Clinical Presentation, Stool Viral RNA Testing, and Outcomes. American Journal of Gastroenterology. April 15, 2020.
Ghimire S, Sharma S, Patel A, et al. Diarrhea Is Associated With Increased Severity of Disease in COVID-19: Systemic Review and Metaanalysis. SN Comprehensive Clinical Medicine. January 6, 2021.
COVID Long Haulers: Gastrointestinal Symptoms. Harvard University.
Colonoscopy. Mayo Clinic. May 18, 2022.