What is Diarrhea

Diarrhea is an uncomfortable condition where you have loose, watery and more-frequent bowel movements (loose or liquid stools) that can have many causes. If you have diarrhea, you will experience an increase in the volume, wateriness or frequency of your bowel movements. You have diarrhea if you have loose stools three or more times in one day 1. Acute diarrhea is diarrhea that lasts 1 to 2 days, but it may last longer and then it goes away on its own. Acute diarrhea is a common problem. Diarrhea lasting more than a few days may be a sign of a more serious problem. Persistent diarrhea lasts 2 to 4 weeks. Acute and persistent diarrhea are typically caused by a bacterial, viral or parasitic infection of some sort. Chronic diarrhea is diarrhea that lasts at least 4 weeks. Chronic diarrhea can be a symptom of a chronic disease 1. Chronic diarrhea symptoms may be continual, or they may come and go.

People of all ages can get diarrhea. On average, adults In the United States have acute diarrhea once a year. Young children have it an average of twice a year. Diarrhea in children is often due to ‘gastro’ — viral gastroenteritis — which is infectious and easily spread from person to person.

People who visit developing countries are at risk for traveler’s diarrhea. Travelers’ diarrhea is caused by eating food or drinking water contaminated with bacteria, viruses, or parasites. Travelers’ diarrhea is most often acute. However, some parasites cause diarrhea that lasts longer. Travelers’ diarrhea can be a problem for people traveling to developing countries.

Most cases of diarrhea is mild and will go away on their own without treatment. However, in some cases, diarrhea can be severe (greater than 10 bowel movements a day or diarrhea where fluid losses are significantly greater than oral intake) can cause dehydration, which can be life-threatening if untreated, needing admission to hospital.

Dehydration is particularly dangerous in children, older adults and those with weakened immune systems. Babies, children, older adults, and people with weakened immune systems can become very sick very quickly and may need to go to hospital. It’s therefore important to recognize the signs of dehydration.

Diarrhea is best treated by replacing lost fluids and electrolytes to prevent dehydration. Depending on the cause of the diarrhea, you may need medicines to stop the diarrhea or treat an infection.

Adults with diarrhea should drink water, fruit juices, sports drinks, sodas without caffeine, and salty broths. As your symptoms improve, you can eat soft, bland food.

Children with diarrhea should be given oral rehydration solutions to replace lost fluids and electrolytes.

Recipe to make oral rehydration fluid:

  • 6 teaspoons of sugar.
  • ½ a teaspoon of salt.
  • 1 liter of boiled water.
  • Stir the mixture until the salt and sugar dissolve.
When to see a doctor

Diarrhea can become dangerous if it leads to severe dehydration. Diarrhea may also signal a more serious problem.

Seek medical attention for a child with these symptoms:

  • Diarrhea that doesn’t improve after 24 hours.
  • No wet diaper in three or more hours.
  • A fever of more than 102 °F (39 °C).
  • Stools that are black and tarry.
  • Stools containing blood or pus.
  • Severe pain in the abdomen or rectum
  • A dry mouth or tongue or cries without tears.
  • Unusually sleepy, drowsy, unresponsive or irritable.
  • A sunken appearance to the abdomen, eyes or cheeks.
  • Skin that doesn’t flatten if pinched and released.

See a doctor for an adult with these symptoms:

  • Diarrhea lasts more than two days without improvement.
  • Excessive thirst, dry mouth or skin, little or no urination, severe weakness, dizziness or lightheadedness, or dark-colored urine, which could indicate dehydration.
  • Severe abdominal or rectal pain.
  • Bloody or black stools.
  • A fever of more than 102 °F (39 °C).

What should I eat if I have diarrhea?

If you have diarrhea, you may lose your appetite for a short time. In most cases, when your appetite returns, you can go back to eating your normal diet. Parents and caretakers should give children with diarrhea their usual age-appropriate diet and give infants breast milk or formula.

Your doctor may recommend changing your diet to treat some causes of chronic diarrhea, such as lactose intolerance or celiac disease.

What should I avoid eating if I have diarrhea?

You should avoid foods that may make your diarrhea worse, such as:

  • alcoholic beverages
  • drinks and foods containing caffeine
  • dairy products such as milk, cheese, and ice cream
  • fatty and greasy foods
  • drinks and foods containing fructose
  • fruits such as apples, peaches, and pears
  • spicy foods
  • diet drinks and sugarless gum and candies containing sweeteners such as sorbitol, mannitol, and xylitol

Research shows that following a restricted diet does not help treat diarrhea in most cases. Most experts do not recommend fasting or following a restricted diet when you have diarrhea.

Types of diarrhea

Diarrhea is loose, watery stools three or more times a day. Diarrhea may be acute, persistent, or chronic:

  • Acute diarrhea is a common problem that typically lasts 1 or 2 days and goes away on its own.
  • Persistent diarrhea lasts longer than 2 weeks and less than 4 weeks.
  • Chronic diarrhea lasts at least 4 weeks. Chronic diarrhea symptoms may be continual or may come and go.

Causes of diarrhea

There are many different causes of diarrhea. Diarrhea can be caused by a short-term illness that clears up in a few days, or it may be a symptom of an ongoing problem or chronic condition.

The most common causes of diarrhea include:

  • Bacteria from contaminated food or water
  • Viruses such as the flu, norovirus, or rotavirus . Rotavirus is the most common cause of acute diarrhea in children.
  • Parasites, which are tiny organisms found in contaminated food or water e.g., cryptosporidium and giardia
  • Medicines such as antibiotics, cancer drugs, and antacids that contain magnesium
  • Food intolerances and sensitivities, which are problems digesting certain ingredients or foods. An example is lactose intolerance.
  • Diseases that affect the stomach, small intestine, or colon, such as Crohn’s disease
  • Problems with how the colon functions, such as irritable bowel syndrome (IBS)

Acute or persistent diarrhea causes may include:

  • Antibiotic-associated diarrhea (or other medication side effects)
  • Artificial sweeteners
  • Clostridium difficile (C. difficile) infection
  • Cryptosporidium infection
  • Cytomegalovirus (CMV) infection
  • Escherichia coli (E. coli)
  • Food intolerances
  • Food poisoning
  • Fructose intolerance
  • Giardia infection (giardiasis) (or other infections causes by parasites)
  • Lactose intolerance
  • Norovirus infection
  • Medicines, such as antacids containing magnesium and some cancer treatments
  • Rotavirus
  • Salmonella infection (or other infections that may occur from bacteria)
  • Shigella infection
  • Stomach surgery
  • Traveler’s diarrhea

Chronic diarrhea causes may include:

  • Celiac disease
  • Colon cancer
  • Crohn’s disease (a type of inflammatory bowel disease)
  • Diverticulitis
  • Inflammatory bowel disease (IBD)
  • Irritable bowel syndrome (IBS)
  • Medications used to treat heartburn, such as proton pump inhibitors and H-2 receptor antagonists
  • Radiation therapy
  • Small intestinal bacterial overgrowth (SIBO)
  • Ulcerative colitis (a type of inflammatory bowel disease)
  • Whipple’s disease

Some infections, such as giardia or Clostridium difficile (C. difficile) infection, may lead to chronic diarrhea if not treated.

Some people also get diarrhea after stomach surgery, because sometimes the surgeries can cause food to move through your digestive system more quickly.

People who are immunosuppressed or have weakened immune systems, such as those living with cancer, HIV/AIDS or who have had an organ transplant, are more likely to develop ongoing diarrhea as a result of a bout of gastroenteritis.

Sometimes no cause can be found. If your diarrhea goes away within a few days, finding the cause is usually not necessary.


Three types of infections that cause diarrhea include:

  • Viral infections. Many viruses cause diarrhea, including norovirus and rotavirus. Viral gastroenteritis is a common cause of acute diarrhea.
  • Bacterial infections. Several types of bacteria can enter your body through contaminated food or water and cause diarrhea. Common bacteria that cause diarrhea include Campylobacter, Escherichia coli (E. coli), Salmonella, and Shigella.
  • Parasitic infections. Parasites can enter your body through food or water and settle in your digestive tract. Parasites that cause diarrhea include Cryptosporidium enteritis, Entamoeba histolytica, and Giardia lamblia.

Infections in the digestive tract that spread through foods or drinks are called foodborne illnesses.

Infections lasting more than 2 weeks and less than 4 weeks can cause persistent diarrhea.

Side effects of medicines

Many medicines may cause diarrhea. Medicines that may cause diarrhea include antibiotics, antacids containing magnesium, and medicines used to treat cancer.

Chronic diarrhea causes

Some infections, food allergies and intolerances, digestive tract problems, abdominal surgery, and long-term use of medicines can cause chronic diarrhea.

Irritable Bowel Syndrome (IBS)

Irritable bowel syndrome (IBS) is a group of symptoms that occur together, including repeated pain in your abdomen and changes in your bowel movements, which may be diarrhea, constipation, or both 2. With IBS, you have these symptoms without any visible signs of damage or disease in your digestive tract.

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder defined as chronically abnormal bowel habits (diarrhea and/or constipation) associated with abdominal pain in the absence of any pathology. Functional gastrointestinal disorders, which doctors now call disorders of gut-brain interactions, are related to problems with how your brain and your gut work together 2. These problems can cause your gut to be more sensitive and change how the muscles in your bowel contract. If your gut is more sensitive, you may feel more abdominal pain and bloating. Changes in how the muscles in your bowel contract lead to diarrhea, constipation, or both.

Symptoms of IBS are usually worsened by stress. The symptoms are generally described as crampy lower abdominal pain with associated diarrhea, constipation, or alternating diarrhea and constipation. Symptoms are often alleviated by defecation, although this is not necessary for diagnosis. For patients with diarrhea, they usually describe their bowel movements as being small or moderate amounts of loose stool. Usually, the bowel movements are associated with urgency 3.


Certain medications are known to induce diarrhea in patients. Currently, there are greater than 700 drugs which are associated with diarrhea. When the offending agent is discontinued, diarrhea may stop within as little as a day but may take longer if there is an injury to the intestinal mucosa. Some medicines, such as antibiotics, can change the normal gut flora and increase your chances of infection with Clostridioides difficile, a bacterium that can cause chronic diarrhea. Patients who are receiving chemotherapy can have diffuse or segmental colitis 4. Olmesartan producing a sprue-like enteropathy was first described in 2012. In this disease state, the intestinal mucosa will mimic the findings of celiac sprue, but the patients are not actually insensitive to gluten 5.

Crohn disease

Crohn’s disease is a chronic (long lasting), progressive, and disabling inflammatory bowel disease (IBD) 6. Ulcerative colitis and microscopic colitis are other common types of inflammatory bowel disease (IBD). Crohn’s disease causes inflammation and irritation in your digestive tract and can involve any site of your gastrointestinal tract from your mouth to your anus, and the inflammation caused by Crohn’s disease often spreads deep into the layers of affected bowel tissue. Most commonly, Crohn’s disease affects your small intestine and the beginning of your large intestine. Crohn’s disease sometimes may lead to life-threatening complications, such as bowel strictures, perforations, and fistula formation. Crohn’s disease causes inflammation of your digestive tract, which can lead to abdominal pain, severe diarrhea, fatigue, fever, weight loss, abdominal masses, anemia and malnutrition 7. Inflammation caused by Crohn’s disease can involve different areas of the digestive tract in different people. Extraintestinal manifestations of Crohn’s disease include osteoporosis, arthritis (inflammation of one or more joints, causing pain and stiffness), scleritis (inflammation involving the white part of the eye [sclera]), kidney stones (nephrolithiasis), gallstones (cholelithiasis) and erythema nodosum (an inflammatory disorder affecting subcutaneous fat, it presents as tender red bumps found symmetrically on the shins). Crohn’s disease most often begins gradually and can become worse over time. You may have periods of remission that can last for weeks or years.

Ulcerative colitis

Ulcerative colitis is a chronic (long lasting), progressive, and disabling inflammatory bowel disease (IBD) that causes inflammation—irritation or swelling—and ulcers (sores) on the inner lining of your large intestine (colon) and rectum. Crohn’s disease and microscopic colitis are other common types of inflammatory bowel disease (IBD). Ulcerative colitis always involves the last part of the colon (the rectum). It can go higher up in the colon, up to involving the whole colon. Ulcerative colitis never has the “skip” areas typical of Crohn’s disease. That is damaged areas are continuous (not patchy) – usually starting at the rectum and spreading further into the colon. In ulcerative colitis the inflammation is present only in the innermost (deepest) layer of the lining of your large intestine (colon). Ulcerative colitis most often begins gradually and can become worse over time. However, it can also start suddenly. Symptoms can range from mild to severe and the symptoms may come and go. These occurrences are called flare-ups. In between periods of flare-ups—times when people have symptoms—most people have periods of remission—times when symptoms disappear. Periods of remission can last for weeks or years. Flare-ups can last many months and may come back at different times throughout your life. Typically, patients with ulcerative colitis experience periods of relapse and remission. Up to 90% will have one or more relapses after the first attack, and early relapse or active disease in the first 2 years is associated with a worse disease course subsequently 8. The goal of treatment is to keep people in remission long term.

Microscopic colitis

Microscopic colitis is a long-standing (chronic) inflammation of the colon (large intestine) that a health care provider can see only with a microscope because the tissue may appear normal with colonoscopy or flexible sigmoidoscopy 9, 10. Inflammation is the body’s normal response to injury, irritation, or infection of tissues. Microscopic colitis is a type of inflammatory bowel disease (IBD), the general name for diseases that cause irritation and inflammation in the intestines. Crohn’s disease and ulcerative colitis are other common types of inflammatory bowel disease (IBD). Unlike the other types of inflammatory bowel disease (Crohn’s disease and ulcerative colitis), microscopic colitis does not increase your risk of developing colon cancer 11.

Microscopic colitis is described by a clinicopathological triad characterized by a history of chronic or intermittent watery diarrhea, normal or almost normal endoscopic examination of the colon (e.g., with slight edema, erythema, and/or loss of vascular pattern, although rarely more significant macroscopic changes are reported, including pseudomembranes and ‘cat scratch changes’) 12, as well as a distinct histological pattern when examined under a microscope – hence the name microscopic colitis 13.

Microscopic colitis is divided into two subtypes: collagenous colitis and lymphocytic colitis. The two types cause different changes in colon tissue 14:

  • Lymphocytic colitis, the colon lining contains more white blood cells than normal. The layer of collagen under the colon lining is normal or only slightly thicker than normal.
  • Collagenous colitis, the layer of collagen under the colon lining is thicker than normal. The colon lining may also contain more white blood cells than normal.
  • Incomplete microscopic colitis, in which there are mixed features of collagenous and lymphocytic colitis.

Celiac disease

Celiac disease is a chronic digestive and immune disorder that damages the small intestine. The disease is triggered by eating foods containing gluten. Gluten is a protein found naturally in wheat, barley, and rye, and is common in foods such as bread, pasta, cookies, and cakes. Many products contain gluten, such as prepackaged foods, lip balms and lipsticks, toothpastes, vitamin and nutrient supplements, and, rarely, medicines.

Celiac disease can be serious. The disease can cause long-lasting digestive problems and keep your body from getting all the nutrients it needs. Celiac disease can also affect the body outside the small intestine.

Celiac disease is different from gluten sensitivity or wheat intolerance. If you have gluten sensitivity, you may have symptoms like those of celiac disease, such as abdominal pain and tiredness. Unlike celiac disease, gluten sensitivity does not damage the small intestine.

Celiac disease is also different from a wheat allergy, a type of food allergy. In both cases, your body’s immune system reacts to wheat. However, some symptoms of wheat allergies, such as having itchy eyes or a hard time breathing, are different from celiac disease. Wheat allergies also do not cause long-term damage to the small intestine.

Lactose intolerance

Lactose intolerance is a condition in which you have digestive symptoms—such as bloating, diarrhea, and gas—after you consume foods or drinks that contain lactose. Lactose is a sugar that is naturally found in milk and milk products, like cheese or ice cream.

In lactose intolerance, digestive symptoms are caused by lactose malabsorption. Lactose malabsorption is a condition in which your small intestine cannot digest, or break down, all the lactose you eat or drink.

Not everyone with lactose malabsorption has digestive symptoms after they consume lactose. Only people who have symptoms are lactose intolerant.

Most people with lactose intolerance can consume some amount of lactose without having symptoms. Different people can tolerate different amounts of lactose before having symptoms.

Lactose intolerance is different from a milk allergy. A milk allergy is an immune system disorder.

Malabsorption syndromes

This term is very nonspecific and encompasses any disorder where the intestine has a decreased ability to absorb nutrients while not requiring intravenous supplementation for health and/or growth 15.

Chronic pancreatitis

Chronic pancreatitis is a long-lasting pancreatitis (inflammation of the pancreas). The pancreas does not heal or improve. Instead, it gets worse over time, which can lead to lasting damage to your pancreas.

Pancreatic enzymes are essential for proper digestion of fats, proteins, and carbohydrates. Patients with chronic pancreatitis will develop recurrent bouts of acute pancreatitis and chronic abdominal pain. Chronic pancreatitis will eventually lead to scarring and fibrosis of the pancreas, which will decrease the number of pancreatic enzymes, and malabsorption. This will lead to excessive amounts of fat in your stool (steatorrhea) and weight loss 16.

Post-cholecystectomy diarrhea

Diarrhea after a cholecystectomy (surgery to remove your gallbladder) occurs in up to 12% of patients. Over time, symptoms generally resolve on their own without intervention 17. Since the gallbladder is removed, the bile produced by the liver directly enters the colon instead of being stored. The increased amount of bile acids in the colon produces diarrhea 18.


Some infections from bacteria and parasites that cause diarrhea do not go away quickly without treatment. Also, after an infection, people may have problems digesting carbohydrates such as lactose or proteins in foods such as cow’s milk, milk products, or soy. Problems digesting carbohydrates or proteins can prolong diarrhea.

Chronic infections

Certain long-lasting infections of the gastrointestinal tract can be linked to chronic diarrhea. A few of these infections include C. difficile, Vibrio cholerae, Salmonella, Shigella, Entamoeba histolytica, E. Coli, Giardia, Cryptosporidium, Whipple Disease, and Cyclospora 19. A clinician should always have a suspicion for an infectious cause of diarrhea. Risk factors include travel and immunosuppression.

Food allergies and intolerances

Allergies to foods such as cow’s milk, soy, cereal grains, eggs, and seafood may cause chronic diarrhea.

Lactose intolerance is a common condition that may cause diarrhea after eating foods or drinking liquids that contain milk or milk products.

Fructose intolerance is a condition that may cause diarrhea after eating foods or drinking liquids that contain fructose, a sugar found in fruits, fruit juices, and honey. Fructose is added to many foods and soft drinks as a sweetener called high-fructose corn syrup.

Sugar alcohols such as sorbitol, mannitol, and xylitol may cause diarrhea in some people. Sugar-free candies and gum often include these sugar alcohols.

Digestive tract problems

Digestive tract problems that may cause chronic diarrhea include:

  • celiac disease
  • Crohn’s disease
  • irritable bowel syndrome and other functional gastrointestinal disorders
  • small intestinal bacterial overgrowth
  • ulcerative colitis

Abdominal surgery

You may develop chronic diarrhea after abdominal surgery. Abdominal surgery is an operation on the appendix, gallbladder, large intestine, liver, pancreas, small intestine, spleen, or stomach.

Can diarrhea be prevented?

Two types of diarrhea can be prevented – rotavirus diarrhea and traveler’s diarrhea. There are vaccines for rotavirus. They are given to babies in two or three doses.

Travelers’ diarrhea

To reduce your chances of getting travelers’ diarrhea when traveling to developing countries be careful about what you eat and drink:

  • avoid drinking tap water
  • avoid using tap water to make ice, prepare foods or drinks, or brush your teeth
  • avoid drinking juice or milk or eating milk products that have not been pasteurized—heated to kill harmful microbes—viruses, bacteria, and parasites
  • avoid eating food from street vendors
  • avoid eating meat, fish, or shellfish that is raw, undercooked, or not served hot. Make sure that the cooked food you eat is fully cooked and served hot.
  • avoid eating raw vegetables and most raw fruits

You can drink bottled water, soft drinks, and hot drinks such as coffee or tea made with boiling water.

Use only bottled or purified water for drinking, making ice cubes, and brushing your teeth.

If you are worried about travelers’ diarrhea, talk with your doctor before traveling. Doctors may recommend taking antibiotics before and during a trip to help prevent travelers’ diarrhea. Early treatment with antibiotics can shorten a case of travelers’ diarrhea.

Foodborne illnesses

You can prevent foodborne illnesses that cause diarrhea by properly storing, cooking, cleaning, and handling foods.


You can reduce your chances of getting or spreading infections that can cause diarrhea by washing your hands thoroughly with soap and warm water for 15 to 30 seconds:

  • after using the bathroom
  • after changing diapers
  • before and after handling or preparing food

Rotavirus, which causes viral gastroenteritis, was the most common cause of diarrhea in infants before rotavirus vaccines became available. Rotavirus vaccines have reduced the number of cases of rotavirus and hospitalizations due to rotavirus among children in the United States 20, 21, 22.

Two oral vaccines are approved to protect children from rotavirus infections:

  • Rotavirus vaccine, live, oral, pentavalent (RotaTeq). Doctors give infants this vaccine in three doses: at 2 months of age, 4 months of age, and 6 months of age.
  • Rotavirus vaccine, live, oral (Rotarix). Doctors give infants this vaccine in two doses: at 2 months of age and at 4 months of age.

For the rotavirus vaccine to be effective, infants should receive all doses by 8 months of age. Infants 15 weeks of age or older who have never received the rotavirus vaccine should not start the series.

Parents or caregivers of infants should discuss rotavirus vaccination with a doctor.

Diarrhea signs and symptoms

As well as the loose and watery stools of diarrhea, you may sometimes have other symptoms, including:

  • an urgent need to go to the toilet
  • loss of bowel control
  • nausea (feeling sick)
  • vomiting
  • fever
  • headache
  • bloating and flatulence (excess gas)
  • abdominal cramps, with a colicky pattern
  • stomach pains
  • loss of appetite
  • weakness
  • dehydration

If a virus or bacteria is the cause of your diarrhea, you may also have a fever, chills, and bloody stools.


Diarrhea can cause dehydration, which means that your body does not have enough fluid to work properly. Dehydration can be serious, especially for babies, children, older adults, and people with weakened immune systems. Babies and young children are much more likely than adults to become dehydrated when they have diarrhea. Babies, children, older adults, and people with weakened immune systems can become very sick very quickly and may need to go to hospital. It’s therefore important to recognize the signs of dehydration.

If you have mild to moderate dehydration, you might:

  • be thirsty
  • have a dry mouth, lips and tongue
  • be dizzy or light-headed, particularly when standing up
  • have a headache
  • have dark urine and not so much urine as normal

If you have severe dehydration, you might:

  • be extremely thirsty
  • have a very dry mouth
  • be breathing fast
  • have a fast heart rate and a low blood pressure
  • have a fever
  • have little or no urine
  • be irritable, drowsy, or confused

Signs of dehydration in babies, infants and children include:

  • dry mouth, tongue and lips
  • sunken eyes, cheeks, or soft spot in the skull
  • being listless or irritable
  • shedding fewer tears when crying
  • urinating less than usual, or no wet diapers for 3 hours or more

Severe dehydration is a medical emergency and can be fatal — get medical help for your child immediately.

Severe dehydration symptoms in babies, infants and children include:

  • not drinking much or refusing drink
  • feeling lethargic
  • producing no urine or only a very reduced amount of urine
  • very sunken eyes
  • very sunken fontanelle in a baby
  • cold, pale or blotchy skin
  • fast breathing.


Diarrhea may cause malabsorption – a condition in which your small intestine cannot absorb nutrients from foods.

Symptoms of malabsorption in adults may include:

  • bloating
  • changes in appetite
  • gas
  • loose, greasy, foul-smelling bowel movements
  • weight loss

Symptoms of malabsorption in infants, toddlers, and young children may include:

  • bloating
  • changes in appetite
  • gas
  • loose, greasy, foul-smelling bowel movements
  • weight loss or poor weight gain

What are the complications of diarrhea?


Diarrhea may cause dehydration, which means your body lacks enough fluid and electrolytes to work properly. Your body loses more fluid and electrolytes in loose stools than solid stools.


Diarrhea may cause malabsorption. If people do not absorb enough nutrients from the food they eat, they may become malnourished. Certain conditions that cause chronic diarrhea—such as infections, food allergies and intolerances, and certain digestive tract problems—may also cause malabsorption.

Diarrhea diagnosis

Diarrhea can be diagnosed based on your medical and family history, a physical exam, or tests to find the cause of your diarrhea.

Doctors do not typically need to find a cause of acute diarrhea. If your diarrhea lasts longer than 4 days or you have symptoms such as fever or bloody stools, your doctor may need to find the cause.

Sometimes, tests will be needed to diagnose an underlying condition. These include:

  • blood tests
  • stool tests
  • endoscopy or colonoscopy
  • biopsy (very rarely)

If you have ongoing diarrhea, your doctor may refer you to a gastroenterologist or other specialist to work out the underlying cause.

Medical and family history

Your doctor will ask for information about your symptoms, such as:

  • how long you have had diarrhea
  • how much stool you have passed
  • how often you have diarrhea
  • how your stool looks, such as color or consistency
  • whether you have other symptoms along with diarrhea

Your doctor will ask about the foods you eat and the beverages you drink. If your doctor suspects you have a food allergy or intolerance, he or she may recommend that you change what you eat to see if your symptoms improve.

Your doctor will also ask about:

  • current and past medical conditions
  • prescription and over-the-counter medicines
  • recent contact with other people who are sick
  • recent travel to developing countries

Your doctor may ask whether anyone in your family has a history of conditions that cause chronic diarrhea, such as celiac disease, Crohn’s disease, irritable bowel syndrome, lactose intolerance, and ulcerative colitis.

Physical exam

During a physical exam, your doctor may:

  • check your blood pressure and pulse for signs of dehydration
  • examine your body for signs of fever or dehydration
  • use a stethoscope to listen to sounds in your abdomen
  • tap on your abdomen to check for tenderness or pain

Sometimes, doctors perform a digital rectal exam. Your doctor will have you bend over a table or lie on your side while holding your knees close to your chest. After putting on a glove, the doctor will slide a lubricated finger into your anus to check for blood in your stool.

Stool test

Stool tests can show the presence of blood, bacteria, or parasites; or signs of diseases and disorders. A health care professional will give you a container for catching and storing the stool. You will receive instructions on where to send or take the container for analysis.

Blood tests

A health care professional may take a blood sample to test for certain diseases or disorders that can cause diarrhea.

Hydrogen breath test

This test is used to diagnose lactose intolerance by measuring the amount of hydrogen in your breath. Normally, little hydrogen is detectable in your breath. With lactose intolerance, undigested lactose produces high levels of hydrogen in your breath. For this test, you will drink a beverage that contains a known amount of lactose. You will then breathe into a balloon-type container that measures your breath hydrogen level. If the hydrogen level is high, your doctor will diagnose lactose intolerance.

Fasting tests

To find out if a food intolerance or allergy is causing your diarrhea, your doctor may ask you to avoid foods with lactose, carbohydrates, wheat, or other ingredients to see whether your diarrhea responds to a change in diet.


Your doctor may use endoscopy to look inside your body to help find the cause of your diarrhea. Endoscopic procedures include:

  • colonoscopy
  • flexible sigmoidoscopy
  • upper gastrointestinal (GI) endoscopy

Diarrhea treatment

It is important to take plenty of fluid with sugar and salt to treat or prevent dehydration 23. Salt and sugar together in a beverage called rehydration therapy can help your intestine absorb fluids. In more severe cases of diarrhea, IV fluid rehydration may be necessary 24.

If you are an older adult or have a weak immune system, you should also drink oral rehydration solutions, such as Pedialyte, Naturalyte, Infalyte, or CeraLyte. Oral rehydration solutions are liquids that contain glucose and electrolytes.

Recipe to make oral rehydration fluid:

  • 6 teaspoons of sugar.
  • ½ a teaspoon of salt.
  • 1 liter of boiled water.
  • Stir the mixture until the salt and sugar dissolve.

Eating foods that are lower in fiber may aid in making stool firmer. A bland ‘BRAT’ diet including bananas, toast, oatmeal, white rice, applesauce and soup/broth is well tolerated and may improve symptoms 25.

To treat or prevent dehydration, give your child liquids that contain electrolytes. You can also give your child an oral rehydration solution, such as Pedialyte, Naturalyte, Infalyte, or CeraLyte, as directed. Talk to a doctor about giving these solutions to your infant.

You can give your child his or her usual age-appropriate diet. You can give your infant breast milk or formula as usual.

In most cases, you can treat your acute diarrhea with over-the-counter medicines such as loperamide (Imodium) and bismuth subsalicylate (Pepto-Bismol, Kaopectate) 26. Doctors generally do not recommend using over-the-counter medicines for people who have bloody stools or fever, which are signs of infection with bacteria or parasites, because they can worsen severe intestinal infections. If your diarrhea lasts more than 2 days, see a doctor right away.

Over-the-counter medicines to treat acute diarrhea in adults can be dangerous for infants, toddlers, and young children. Talk to a doctor before giving your child an over-the-counter medicine. If your child’s diarrhea lasts more than 24 hours, see a doctor right away.

Probiotic supplementation has been shown to reduce the severity and duration of symptoms and should be encouraged in patients with acute diarrhea.

Empiric antibiotic therapy with an oral fluoroquinolone can be considered in patients with more severe symptoms.

Oral rehydration solutions

These are available over the counter from your pharmacist. For older people and children, oral rehydration solutions are a better choice than plain water. They are made specifically to replace both fluids and electrolytes (important minerals that your body needs to function) in the right concentrations. Sports rehydration drinks are not recommended.

Table 1. Treatment of dehydration

Extent of Dehydration Rehydration Therapy Replacement of Losses
Minimal or no dehydrationNot needed
  • Less than 10 kg bodyweight – give 60-120 mL of oral rehydration solution for each episode of loose stool or vomiting
  • More than 10 kg bodyweight – give 120-140 mL of oral rehydration solution for each episode of loose stool and vomiting
Mild-to-moderate dehydration50-100 mL/kg of oral rehydration solution to be given over 3-4 hours
  • Less than 10 kg bodyweight – give 60-120 mL of oral rehydration solution for each episode of loose stool or vomiting
  • More than 10 kg bodyweight – give 120-140 mL of oral rehydration solution for each episode of loose stool and vomiting
Severe dehydrationIntravenous fluids, such as normal saline or lactated Ringer solution (20 mL/kg until perfusion and mental state improve), followed by oral rehydration solution 100 mL/kg over 4 hours or half normal saline (5% dextrose) IV at twice maintenance fluid rates
  • Less than 10 kg bodyweight – give 60-120 mL of oral rehydration solution for each episode of loose stool or vomiting
  • More than 10 kg bodyweight – give 120-140 mL of oral rehydration solution for each episode of loose stool and vomiting

If unable to drink, give through nasogastric tube or IV 5% dextrose (one-fourth normal saline) along with 20 mEq/L potassium chloride

[Source 27 ]

Anti-diarrheal medicines

Anti-diarrheal medicines should not be used to treat a diarrhea attack in babies or children.

Your pharmacist or doctor will be able to advise you if you are thinking of taking over-the-counter anti-diarrheal medicines. They are not suitable for use in the case of diarrhea caused by certain specific infections. Do not take them if you have a fever or have blood in your stool.

Remember that diarrhea is your body’s way of getting rid of a gastrointestinal infection, so these medicines should not be taken long term because they slow your gut and may prolong your illness.

Anti-vomiting drugs

Anti-emetics may be prescribed by your doctor if you have gastroenteritis and are having problems due to vomiting.

Intravenous fluids

People who are not able to adequately rehydrate — for example, because they are vomiting — may need to be given intravenous fluids via a drip.


Most sudden attacks of diarrhea are caused by viruses and so antibiotics, which are only used to treat bacterial infections, are of no use. If your doctor determines — usually through testing a stool sample — that your diarrhea is due to a bacterial or parasitic infection, then they may prescribe antibiotics.

Dietary changes

If you are experiencing diarrhea for dietary reasons or due to irritable bowel syndrome, an accredited practising dietitian should be able to suggest some dietary changes.

Persistent and chronic diarrhea treatment

How doctors treat persistent and chronic diarrhea depends on the cause made after initial testing. Doctors may prescribe antibiotics and medicines that target parasites to treat bacterial or parasitic infections. Doctors may also prescribe medicines to treat some of the conditions that cause chronic diarrhea, such as Crohn’s disease, irritable bowel syndrome, or ulcerative colitis. How doctors treat chronic diarrhea in children also depends on the cause.

Doctors may recommend probiotics. Probiotics are live microorganisms, most often bacteria, that are similar to microorganisms you normally have in your digestive tract. Researchers are still studying the use of probiotics to treat diarrhea.

For safety reasons, talk with your doctor before using probiotics or any other complementary or alternative medicines or practices. If your doctor recommends probiotics, talk with him or her about how much probiotics you should take and for how long.

Diarrhea prognosis

Acute diarrhea typically lasts 1 or 2 days and goes away on its own without treatment. The prognosis for chronic diarrhea varies widely based on the cause of chronic diarrhea 28. For patients with a non-specific diagnosis, the prognosis is generally very good. The standard therapy used to treat nonspecific diarrhea such as opioid agonists are very effective 29.

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