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Watery Diarrhea Symptoms, Causes & Common Questions

Watery diarrhea is commonly caused by a viral infection or food poisoning from eating undercooked meat or rotten foods. It can be serious if it causes dehydration. Keep an eye out for blood in the stool, and be sure to drink water and fluids with electrolytes.
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Last updated September 24, 2021

Diarrhea questionnaire

Answer our clinicians' questions to get a diarrhea treatment prescription for $25 and know if your diarrhea is serious.

Diarrhea questionnaire

Answer our clinicians' questions to get a diarrhea treatment prescription for $25 and know if your diarrhea is serious.

See diarrhea treatment options

Only available in: CA, NY, TX, FL, IL, NC, PA, OH, MI, and WA

Watery diarrhea symptoms explained

Watery diarrhea is a common sign of infection, but can also be caused by other inflammatory diseases, or cancer-related diagnoses. For most people, watery diarrhea is dangerous only if it causes severe dehydration. As the body eliminates the infections and repairs the walls of the intestines, symptoms resolve within a few weeks. It is important to watch for large amounts of blood in stool and to continue to consume both water and electrolytes to replace the fluid lost through diarrhea. For the vast majority of people, if you can deal with diarrhea responsibly with fluid replacement, you will recover well. This article will discuss both the most common and most dangerous causes of watery diarrhea.

Common characteristics of watery diarrhea

Associated characteristics of watery diarrhea may include the following.

What causes watery diarrhea?

Acute causes

Acute causes are those that have a sudden-onset and a relatively speedy resolution (e.g. one to two weeks). These forms of diarrhea are usually caused by an infection. Unless an individual has a weakened immune system, they can often clear and destroy the infection-causing agent themselves (provided they avoid becoming excessively dehydrated in the process). Accordingly, the treatment for most infectious diarrhea is supportive care with some variations, such as whether you need to take an antibiotic, which will depend on your specific case and stamina.

  • Viruses: Viruses are usually not life-threatening and there are a wide array of viruses that cause diarrhea in different parts of the world and in different seasons. Common types of viruses include norovirus, adenovirus, astrovirus, and rotavirus among others. They can occur in enclosed spaces like cruise ships or college dorms. In all but the very young, very old, and immunosuppressed, they are not life-threatening. If you suspect that you have a virus causing diarrhea, stay hydrated with soups, broths, and electrolyte drinks and get plenty of rest. Remember to wash your hands and keep your living areas sanitized and tidy so the illness doesn't spread to your house or roommates.
  • Bacteria: Bacteria are also rarely life-threatening, but in some select cases can cause more severe diarrhea or can affect other organ systems. Common bacteria include salmonella, campylobacter, shigella, multiple strains of E. Coli, and Clostridium difficile. Similarly to viral causes, most of these types of bacteria will cause illness that resolves on its own. However, Shigella and a type of E. Coli called Enterogenic Hemorrhagic E. Coli can release toxins that interfere with, and, in large amounts, can shut down the proper functioning of the kidneys. When this occurs, dialysis or an artificial filtering system for the kidneys is necessary until they recover.
  • Protozoa: Protozoa are often treated with antibiotics even though the body can frequently eliminate protozoa without treatment. Treatment in most cases shortens the duration, and, importantly, the transmission of the disease to other individuals. Giardia, a type of bacteria that occurs when drinking fresh, untreated water from streams or lakes, is treated with antiprotozoal agents because of its ease of transmission. However, in some cases like Cyclospora, diarrhea can continue unabated for months and it is treated primarily to shorten the duration of infection.

Diarrhea questionnaire

Answer our clinicians' questions to get a diarrhea treatment prescription for $25 and know if your diarrhea is serious.

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Only available in: CA, NY, TX, FL, IL, NC, PA, OH, MI, and WA

Chronic causes

Chronic causes of watery diarrhea are those that are longer-lasting or more difficult to eradicate and may require hospitalization.

  • Chronic infections (C. Difficile, Campylobacter): Some infections like C. difficile occur in part because of treatment for other diseases. C. difficile is a bacterium that lives peacefully in a normal bowel as it is often kept at low levels by normal gut bacteria. However, for individuals treated with antibiotics, the normal gut bacteria may have been killed along with the harmful bacteria causing an infection. This leaves C. difficile unchecked and able to reproduce in large amounts. C. difficile, unless treated with targeted antibiotics for C. difficile and / or the replacement of normal gut bacteria, will continue to produce watery diarrhea. Often treatment of C. difficile requires admission to the hospital for monitoring and proper treatment to avoid dangerous levels of dehydration. It is often (but not always) first treated with the antibiotic vancomycin.
  • Inflammatory bowel disease: This can affect either the small intestine, large intestine, or both. It may produce watery diarrhea, bloody diarrhea, mucus-laden diarrhea or a mixture of the three. It is commonly treated with drugs that temper and lower the immune response. If you have long-standing watery diarrhea that does not respond to antibiotics, you may have inflammatory bowel disease or irritable bowel syndrome. However, a proper diagnosis will require a colonoscopy (or a scope usually inserted through the anus) to examine the walls of the intestines.
  • Irritable bowel syndrome: This can have many different kinds of symptoms. It can manifest as constipation (IBS-C), diarrhea (IBS-D), or mixed (IBS-M). Irritable bowel syndrome with diarrhea is defined as abdominal pain or discomfort lasting at least three days per month with improvement on defecation and onset of discomfort associated with a change in the frequency of stool or the appearance of stool. It should be noted that IBS is a syndrome which means a series of symptoms, not a single disease. Treatments vary widely from avoidance of food allergens and lactose and increasing consumption of fiber and physical activity levels. Irritable bowel syndrome is only diagnosed after inflammatory bowel disease or cancer has been ruled out.

Viral (norovirus) infection

If you ever heard of an entire cruise ship of people coming down with the same “stomach bug,” chances are that was norovirus. Fortunately, norovirus usually goes away on its own after a few days, but is pretty unpleasant and can spread extremely easily. The ...

Food poisoning

Food poisoning, also called foodborne illness or "stomach flu," is an acute infection of the digestive tract from food contaminated with bacteria, viruses, parasites, or other toxins. It actually has no relation to influenza.

Any food can become contaminated if not prepared under clean conditions, cooked thoroughly, or stored at cold temperatures. Meat, fish, dairy products, and fresh fruits and vegetables are some of the most easily contaminated foods.

Symptoms include nausea, vomiting, diarrhea, and abdominal pain, and sometimes fever and chills.

Most people recover on their own with supportive care, meaning rest, fluids, and over-the-counter pain relievers and fever reducers.

However, dehydration can result if the vomiting and/or diarrhea are not controlled and IV fluids may be needed.

If there is also blurred vision, dizziness, or paralysis, the nervous system may be affected due to botulism. This is a medical emergency. Take the patient to the emergency room or call 9-1-1.

Proper food preparation and storage, along with frequent and thorough handwashing, is the best prevention.

Rarity: Common

Top Symptoms: nausea, abdominal pain (stomach ache), headache, abdominal cramps (stomach cramps), dizziness

Symptoms that never occur with food poisoning: severe fever, being severely ill, bloody diarrhea

Urgency: Self-treatment

Diarrhea caused by a bacteria called vibrio

The Vibrio genus of bacteria causes nausea, vomiting, and diarrhea that can be very serious. Vibrio parahaemolyticus and Vibrio vulnificus are two of the species that cause this illness, which is also called vibriosis.

The primary risk factor is eating raw or undercooked seafood, especially oysters from any coastal waters and from the Gulf of Mexico in particular. People with weakened immune systems or liver disease are especially vulnerable to this infection.

Symptoms include fever, vomiting, and diarrhea, sometimes with mental confusion. These symptoms in a person who has recently eaten raw seafood, or has been swimming in ocean or bay water, are considered a medical emergency. Take the patient to the emergency room or call 9-1-1.

Some types of Vibrio-caused illness can worsen very quickly and lead to dehydration and septicemia, which can be life-threatening.

Diagnosis is made through patient history, physical examination, and lab tests on blood, urine, and stool samples.

Treatment will usually involve hospitalization for intravenous fluids, antibiotics, and supportive care.

Rarity: Rare

Top Symptoms: diarrhea, nausea, stomach bloating, headache, abdominal cramps (stomach cramps)

Symptoms that always occur with diarrhea caused by a bacteria called vibrio: diarrhea

Urgency: Self-treatment

Normal occurrence of diarrhea

Diarrhea can be an indication of serious illness – especially in young children – but in some cases it has a much simpler cause and can be easily cured.

If there are simply frequent loose stools – three or more times per day – without other symptoms of illness, the most common cause is food or drink.

Overuse of caffeine, beer, or wine has a laxative effect on some individuals. The artificial sweeteners sorbitol and mannitol are known laxatives, as are some herbal supplements and some over-the-counter vitamin and mineral preparations.

Lactose intolerance, or the inability to digest the natural sugar in milk, causes digestive upset and diarrhea.

Diarrhea can cause dehydration and mineral imbalance no matter what the cause, so it is still important to manage it.

The best treatment is to remove some items or supplements from the diet and watch the results. This will show which items are causing the diarrhea.

It's always wise to use any new supplements in moderation so that if the trouble recurs, the cause will be plain.

Rarity: Common

Top Symptoms: diarrhea, mild diarrhea

Symptoms that always occur with normal occurrence of diarrhea: diarrhea

Symptoms that never occur with normal occurrence of diarrhea: bloody diarrhea, severe diarrhea, worsening diarrhea, being severely ill, ill appearance

Urgency: Self-treatment

Microscopic colitis

Microscopic colitis is caused by inflammation of the large intestine than can only be seen with a microscope. It is believed that microscopic colitis is caused by an overly aggressive immune response to a certain trigger that can be related to medication, an infection, autoimmune diseases, genetics, or a malabsorption of bile.

Symptoms primarily include watery diarrhea accompanied by abdominal pain, cramps or discomfort, and an urgency to use the restroom.

Treatment depends on the cause, such as halting offensive drugs and taking anti-diarrheal medication or steroids. It is also important to make sure you stay hydrated throughout the recovery period.

Rarity: Rare

Top Symptoms: fatigue, nausea, diarrhea, abdominal pain (stomach ache), stomach bloating

Symptoms that always occur with microscopic colitis: diarrhea

Symptoms that never occur with microscopic colitis: bloody diarrhea

Urgency: Primary care doctor

Food poisoning by the staphylococcus bacteria

Food poisoning by staphylococcus bacteria refers to the stomach and intestinal upset caused by eating foods contaminated with the staphylococcus, or "staph," bacteria.

Most often, food is contaminated when the person preparing it did not thoroughly wash their hands first. The staph bacteria quickly multiply in food or milk, producing toxins which actually create the illness. The toxins are not destroyed by cooking and the food may look fresh.

Symptoms develop rapidly, within 30 minutes to a few hours, and include nausea, vomiting, stomach cramping, and diarrhea. The illness itself is not spread from person to person.

Diagnosis is made through patient history and physical examination. Lab tests are usually not necessary, but testing may be done if there is a large outbreak with many people affected in one place.

A food poisoning episode usually resolves on its own within 24 hours. Antibiotics are not effective against the toxins. The symptoms can be treated with rest, plenty of fluids, and electrolyte replacement with sports drinks. Severe cases may need intravenous fluids in a hospital.

Rarity: Uncommon

Top Symptoms: nausea, nausea or vomiting, diarrhea, abdominal cramps (stomach cramps), vomiting

Symptoms that always occur with food poisoning by the staphylococcus bacteria: nausea or vomiting

Urgency: Self-treatment

Traveler's diarrhea

Traveler's diarrhea is a digestive tract disorder that commonly causes loose stools and abdominal cramps. It's caused by eating contaminated food or drinking contaminated water.

Rarity: Common

Top Symptoms: diarrhea, nausea, abdominal pain (stomach ache), fever, stomach bloating

Symptoms that always occur with traveler's diarrhea: diarrhea

Symptoms that never occur with traveler's diarrhea: anxiety

Urgency: Self-treatment

Shigella infection

Shigella infection, or shigellosis, is an intestinal infection caused by a strain of Shigella bacteria.

Shigellosis is highly contagious through fecal matter. Anyone coming into contact with any trace of feces in food, drink, or surfaces can get the disease. Swimming in contaminated water, even in a chlorinated pool or hot tub, is another source of infection.

Most susceptible are young children; travelers to less developed regions; and anyone with a weakened immune system.

Symptoms include fever; abdominal pain and cramps; and severe diarrhea, which may contain blood.

If not treated, there is the risk of dehydration due to the diarrhea and fever. Young children are especially susceptible.

Diagnosis is made through patient history, physical examination, and testing of a stool sample.

Treatment involves rest and fluids. Most cases clear up within a week. Sometimes antibiotics are used in more severe cases, though antibiotics are not effective against some forms of Shigella bacteria.

The best prevention is frequent and thorough handwashing, and good hygiene when preparing food.

Rarity: Rare

Top Symptoms: diarrhea, general abdominal pain, severe diarrhea, watery diarrhea, fatigue

Symptoms that always occur with shigella infection: diarrhea

Urgency: Self-treatment

Intestinal infection with ameba parasite

Visiting or living in places with poor sanitation can lead to parasite infections that can cause long-lasting diarrhea and stomach pain.

Rarity: Rare

Top Symptoms: nausea, loss of appetite, diarrhea, constipation, general abdominal pain

Urgency: Primary care doctor

Diarrhea questionnaire

Answer our clinicians' questions to get a diarrhea treatment prescription for $25 and know if your diarrhea is serious.

See diarrhea treatment options

Only available in: CA, NY, TX, FL, IL, NC, PA, OH, MI, and WA

Treatment for watery diarrhea

Treatments for watery diarrhea vary widely, though they all have the same starting point: stay hydrated. Depending on the eventual cause of watery diarrhea and how long it lasts, you may end up taking antibiotics or undergoing a colonoscopy to examine your intestines for signs of inflammatory disease.

  • Antibiotics: These are common for bacterial and protozoal causes. Remember that you will not receive antibiotics for a viral cause of diarrhea. If your symptoms do not improve within a week of taking antibiotics, you should call your physician and ask whether you need a new appointment.
  • Diagnostic workup: This will be necessary if you have diarrhea that is found to be non-infectious and if it persists for longer than a couple weeks. This may involve a collection of your stool for examination under a microscope and culturing to find out if any pathogen is causing your symptoms. Once a pathogen has been identified, it may be treated with antibiotics. If an inflammatory condition is found, it may be treated over a longer period of time with medications that decrease inflammation in the gut.
  • Dietary restriction: This is a treatment for irritable bowel syndrome. Certain foods like lactose may be undigestible and cause chronic diarrhea, and other foods may cause an allergy that damages the gut and leads to symptoms of irritable bowel syndrome. The process of dietary restriction usually take a longer period of time, and involves cutting out many foods and slowly adding in foods one at a time to determine what is acceptable to the intestines.

Seek immediate treatment for the following

You should seek help without delay if:

  • You have an inability to replace the fluids you are losing
  • You feel dizzy, lightheaded or lose consciousness
  • You do not improve on antibiotics
  • You have symptoms for longer than two days
  • You have a recurrence of symptoms without being exposed to the same initial cause

FAQs about watery diarrhea

Here are some frequently asked questions about watery diarrhea.

What causes watery diarrhea?

Watery diarrhea can be caused by an inability to absorb the water that you drink, the water in food, or the secretion of water from the gut following infection or consumption of something that pulls water from the gut. Common examples are consumption of excess lactose or xylose sugars that are not easily digested as well as cholera.

How do you know when to seek care for dehydration?

If you feel faint, dizzy, or nauseous, or have lost consciousness, you may be dangerously dehydrated. A lack of fluids can cause low blood pressure, confusion, or a loss of consciousness if it is severe. Kidney failure can also occur if a loss of fluid is especially rapid. If you stop urinating for an extended period of time, you should be concerned about potential kidney injury.

When should you seek medical care for watery diarrhea?

If you find blood or mucus in your diarrhea, if you have difficulty maintaining adequate hydration either because of nausea or because of excessive or continuous liquid diarrhea, if you lose consciousness, become confused, stop sweating, or stop urinating you should seek care immediately.

How long does watery diarrhea usually last?

Watery diarrhea can last anywhere from a few days to a few weeks. Often even severe watery diarrhea can and will resolve on its own. It is important, however, to maintain adequate hydration. Diarrhea from a dietary cause will continue until the substance has left your system. Diarrhea from a toxin or from an infection will continue until the body clears the infection or it is treated with antibiotics.

What are some other symptoms of watery diarrhea that may be more dangerous?

Blood in your diarrhea, mucus, completely watery diarrhea, a loss of color in your stool, large amounts of mucus, or symptoms of dehydration may be signs that you should seek urgent or emergent evaluation for complicated abdominal pain or dehydration.

Questions your doctor may ask about watery diarrhea

  • Any fever today or during the last week?
  • Have you experienced any nausea?
  • Have you been feeling more tired than usual, lethargic or fatigued despite sleeping a normal amount?
  • Have you lost your appetite recently?

Self-diagnose with our free Buoy Assistant if you answer yes on any of these questions.

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Dr. Rothschild has been a faculty member at Brigham and Women’s Hospital where he is an Associate Professor of Medicine at Harvard Medical School. He currently practices as a hospitalist at Newton Wellesley Hospital. In 1978, Dr. Rothschild received his MD at the Medical College of Wisconsin and trained in internal medicine followed by a fellowship in critical care medicine. He also received an MP...
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