Watery diarrhea: symptoms, causes, diagnosis, treatment.


For most people, watery diarrhea is a symptom of a stomach illness. It can be caused by a variety of microbes, including viruses, bacteria, and parasites, some of which can be easily treated with medications.

However, in some cases, watery diarrhea can lead to potentially serious or even fatal complications, such as dehydration or malabsorption. This is especially concerning for babies and young children. Learn more about the symptoms, causes , diagnosis, and treatments for watery diarrhea .

Get Medical Information / Cindy Chang


Watery diarrhea means you have loose stools, usually three or more times a day. When these symptoms appear and how long they last depends on what is causing them.

In many cases, the watery diarrhea will go away on its own without any treatment. However, this is not always the case.

Immediate medical attention should be sought if diarrhea persists for more than two days for adults or 24 hours for young children and infants.

You should also seek medical attention if the diarrhea is accompanied by fever, severe abdominal or rectal pain, black or bloody stools, or signs of complications such as dehydration .

Depending on the cause of the illness, diarrhea can sometimes coincide with other gastrointestinal problems such as nausea , vomiting, loss of appetite, or cramps.


Watery diarrhea is usually harmless and temporary, but in some cases it can lead to more serious illness. The two main complications of watery diarrhea are dehydration and malabsorption.


When you have watery diarrhea, your body can easily lose more fluid than you consume. This is called dehydration, and it can be especially dangerous for young children.

The human body is primarily water. It needs water to function properly. Lack of fluid can cause serious problems, including insufficient blood volume (called hypovolemic shock), kidney failure, or even death.

Young babies are at special risk for dehydration because their small bodies cannot store as much water as older children and adults.

When babies lose fluids due to watery diarrhea, it can be difficult to replace them quickly enough to prevent dehydration. This is especially true if the illness causing the diarrhea also causes vomiting or refusal to eat.

For this reason, diarrhea is one of the most serious causes of child death worldwide, killing more than 2,000 children every day, mainly in developing countries.

The signs and symptoms of dehydration vary between children and adults, but generally include :

  • Thirst
  • Dark yellow or brown urine
  • The need to urinate less often than usual.
  • Fatigue or lack of energy
  • Dry mouth
  • Lack of tears when crying (in young children and older babies who have started crying)
  • Decreased skin turgor (when you pinch and release an area of the skin, there is a delay before the skin becomes flat and returns to normal)
  • Sunken eyes, cheeks, or soft spots on the baby's skull
  • Feeling dizzy or fainting


Malabsorption occurs when your body doesn't absorb enough of the nutrients it needs after eating or drinking, which can lead to exhaustion. While diarrhea itself does not necessarily cause malabsorption, some infections that cause diarrhea, such as parasites, can also interfere with the body's ability to properly digest food and absorb the nutrients it needs.

Signs and symptoms of malabsorption include:

  • Bloating, abdominal discomfort, or gas
  • Appetite changes
  • Losing weight or (in children) slowing down weight gain


Several germs can cause watery diarrhea, many of which are spread through contaminated food, water, or objects. The vast majority of cases are caused by viral, bacterial, or parasitic infections. However, certain health conditions can also cause diarrhea.


Viral gastroenteritis occurs when a virus infects the intestines, causing watery diarrhea along with other gastrointestinal symptoms such as cramps and nausea. These viruses often run their course and there are no medications available to treat them.

Many viruses can infect the intestines, but the most common are rotavirus, norovirus, adenovirus, and astrovirus.


Rotavirus is the most common cause of diarrhea in the world, accounting for 40% of young children's admissions associated with diarrhea. In areas where rotavirus vaccination is not available, it is estimated that almost all children will become infected with rotavirus at some point at an early age. childhood, often before the first birthday.


Norovirus is a highly contagious stomach infection that causes about one in five cases of acute gastroenteritis worldwide and the most common cause of foodborne illness in the United States. The virus causes about 400,000 emergency department visits in the United States each year, with the majority of cases in young children .


Worldwide, astroviruses are one of the most common causes of watery diarrhea in young children and adults with weakened immune systems. In most cases, the disease goes away on its own in a few days.


Although adenoviruses are commonly associated with the common cold or pink eye , this group of viruses can also cause mild diarrhea that can last up to two weeks .


Bacterial infections are another common cause of watery diarrhea. There are several types of bacteria that are most commonly associated with watery diarrhea .


Cholera is rarely detected in rich countries like the United States, but outbreaks of the bacteria are common in low-income countries. An estimated 1.3 to 4 million cases of cholera occur each year, resulting in between 21,000 and 143,000 deaths worldwide .

Most people infected with the bacteria do not show any symptoms, although they can pass the bacteria to other people through their feces.

When symptoms occur, watery diarrhea, often referred to as "rice water stools" because it looks like water left over from washing rice, is the most common symptom of illness, followed by vomiting and cramps. In more severe cases, both children and adults can die within a few hours from severe dehydration.


Campylobacter is a common cause of foodborne illness in the United States, causing approximately 1.3 million cases a year. The bacteria are mainly transmitted through undercooked poultry, but can also be found in unpasteurized milk and contaminated water.

Most people infected with Campylobacter will not need antibiotics or medical attention to recover; the disease will eventually go away on its own.

Escherichia coli (Escherichia coli)

E. coli is a group of bacteria that can cause a wide range of symptoms. Some strains cause gastrointestinal upset, while others cause respiratory problems, urinary tract infections, and other illnesses.

The type of E. coli that causes watery (and sometimes bloody) diarrhea is shiga toxin-producing E. coli (STEC), which is spread through contaminated food or drink. Common foods include raw or undercooked ground meat and raw vegetables. and sprouts.


Salmonella is estimated to cause about 1.2 million illnesses and 450 deaths annually in the United States. In most cases, the diarrhea, cramps, and fever associated with a salmonella infection go away on their own without treatment, but in some cases, the diarrhea can become very serious. require hospitalization.

Infections are predominantly associated with contaminated food (the bacteria is found in various raw and processed foods, including sprouts, peanut butter, and chicken nuggets), but the bacteria can also be transmitted from animals to humans.

In early 2019, the Centers for Disease Control and Prevention (CDC) reported an outbreak of Salmonella in several states associated with domestic hedgehogs .


People with shigellosis or an infection with the Shigella bacteria usually start to feel nauseous about a day or two after eating or drinking something contaminated with the bacteria, or having sex with someone who is infected (or has recently been infected). . Symptoms usually resolve within a week, but sometimes it can take months for bowel movements to return to normal.

Boys are more likely to develop shigellosis, although travelers, men who have sex with men, and people with weakened immune systems are also at higher risk of infection. Foods associated with shigellosis are salads, raw vegetables, milk, and dairy products.

Clostridium difficile

Infections with this diarrhea-causing bacteria, more commonly called C. diff or C. difficile , are often a side effect of antibiotic use. As a result, this mainly affects those who frequently visit medical facilities or spend long periods of time in hospitals or nursing homes.

The CDC estimates that around half a million infections and around 15,000 deaths occur annually in the United States alone .


Parasitic infections, which are rare in high-income countries, are a common and persistent cause of chronic diarrhea in areas with poor access to safe water and sanitation. There are many different types of parasites that can contribute to watery diarrhea.


Cryptosporidiosis or "crypto" is caused by microscopic parasites that invade the intestines. These parasites have a tough outer shell that protects them from disinfectants, including bleach. That is why it is still quite common in the United States, despite improvements in sanitation and drinking water.

Cryptography is especially common in diaper-age children attending kindergarten, people who swim or drink from contaminated water sources (such as streams or lakes), and those who travel abroad .


Cyclosporiasis, caused by another microscopic parasite, is caused by ingesting food and water contaminated with Cyclospora cayetanensis . It is transmitted through feces or water contaminated with feces.

The parasite is too small to be seen with the naked eye and lives in the small intestine, where it causes frequent (and sometimes explosive) watery diarrhea. Diarrhea can last from a few days to more than a month . Symptoms can also go away and come back several times if the infection is not treated.


Giardia (also called giardiasis) is an infection of the small intestine caused by the parasite Giardia lamblia . The tiny parasite is most often transmitted through contaminated water sources and poor hygiene.

Cases do not always cause symptoms, but an asymptomatic person, one who has no symptoms, infected with the parasite can still shed it in the stool. When symptoms appear, the most obvious sign is foul, watery diarrhea, along with sulfur dioxide, bloating, and stomach cramps .

Other reasons

While infectious diseases are the most common cause of watery diarrhea, some noncommunicable health conditions can lead to persistent or chronic diarrhea. This includes:


Few people need a healthcare professional to diagnose watery diarrhea. Frequent loose stools are often enough to let the person know they have the condition.

However, if the condition does not improve after a couple of days, or if you or your child develop signs of dehydration, your healthcare provider may want to run several tests to find out what is causing the watery diarrhea. can be effectively treated.

Physical exam

Your healthcare provider will most likely do a physical exam before the test. She will monitor your blood pressure and pulse, and take your temperature to make sure there are no signs of severe dehydration.

You can then use a stethoscope to listen to specific sounds in your abdomen and feel the abdominal area to check for tenderness or pain. While this is not common, your doctor may also check your rectal area (with a gloved finger in the anus) to check for blood in your stool.

Your healthcare provider will likely also ask you a few questions to learn more about your symptoms, including how long you have watery diarrhea, how often you should use the bathroom, what your stools look like (color, consistency, strange odors), and if you have additional symptoms such as nausea or fever.

Also, your healthcare provider will ask if you have recently traveled or taken antibiotics in the past one to two months.

Diagnostic tests

The most common diagnostic tool for determining the cause of watery diarrhea is a stool test. Blood tests, hydrogen breath tests, fasting tests, or endoscopy can also be used for diagnosis.

Stool test

These tests examine stool samples for signs of germs. Stool analysis may show germs such as bacteria or parasites, blood, or signs of other diseases.

Blood test

Blood samples can be tested for a number of diseases or disorders that can cause watery diarrhea. This type of test can indicate a health condition associated with watery diarrhea, such as celiac disease.

Hydrogen breath test

The hydrogen breath test, which is most commonly used to diagnose lactose intolerance, detects unusually high levels of hydrogen in the breath when undigested lactose reaches anaerobic bacteria in the colon.

This test is done by drinking something that contains lactose and inhaling it into a device that measures hydrogen levels. A high level indicates lactose intolerance.

Fasting tests

If your watery diarrhea is caused by allergies or food intolerances, fasting tests can help you determine which food is causing the problem by avoiding certain foods to see if the watery diarrhea goes away.

In some cases, your healthcare provider may recommend an elimination diet, in which you cut a list of foods (such as lactose or wheat) and slowly reintroduce them into your diet to see how your body responds.


Endoscopic procedures (such as colonoscopy and upper endoscopy) use an instrument called an endoscope to look inside the body and identify possible causes of diarrhea.

Watch out

Watery diarrhea is most often treated by addressing the underlying cause of the illness (such as a bacterial infection) or with medications to reduce the severity of the diarrhea. If the disease is caused by bacteria, antibiotics are sometimes used to treat it. an infection, especially if the diarrhea does not go away on its own.

If symptoms are the result of a parasitic infection, antiparasitic medications are sometimes prescribed. However, not everyone with watery diarrhea will need treatment. Many cases go away on their own in a few days.

Even without treatment, it is important to prevent complications such as dehydration until the watery diarrhea subsides.

Tips to prevent dehydration

  • Drink a lot of water
  • Avoid caffeine
  • Replenish electrolyte stores

If you are nauseated or vomiting, frequent small sips (rather than large sips) of water will help you retain the fluid. Also, caffeinated beverages and other diuretics should be avoided.

The caffeine found in coffee and soda can interfere with your body's absorption of fluids, causing you to skip fluids more often than usual. Alcohol can do the same, so it is best avoided as well.

Electrolytes are found in a wide variety of sources, but if you're not feeling well, the easiest way to get them is by drinking drinks with a little salt ( although keep in mind that water should be your main drink).

Sports drinks and specialty moisturizers like Pedialyte work well, or you can make them yourself by adding a pinch of salt to the lemon water and adding a little sweetener like sugar or sugar substitute.


The vast majority of cases of watery diarrhea can be avoided by taking a few precautions, such as clean water and sanitation, washing your hands and caring for food properly, and getting vaccinated .


Most of the germs that cause watery diarrhea are spread through contaminated food and water, often due to unsanitary conditions or practices.

The best ways to prevent infections that cause watery diarrhea are to drink clean filtered water, wash your hands after using the bathroom, and wash your hands before eating.

Safe feeding methods

Some infections that cause watery diarrhea are caused by improper food preparation. Make sure to wash your hands before preparing food, keep fresh food away from raw meat, and cook meat thoroughly. Also, store prepared foods at a suitable temperature and away from pests such as house flies.


Two common causes of diarrhea (rotavirus and cholera) can be prevented with vaccines.

Rotavirus vaccine

Rotavirus vaccination is part of the routine childhood immunization program recommended by the US Centers for Disease Control and Prevention. It is administered orally in two or three doses (depending on the brand) starting at 2 months of age. Although the vaccine is recommended by healthcare providers, it is rarely required for registration in child care facilities.

Perhaps as a result, rotavirus vaccination rates in the United States often lag behind those of other vaccines of the same age. For example, only about 73% of children aged 19 to 35 months were vaccinated against rotavirus in 2017, compared to 91.5% who were vaccinated against measles.

Cholera Vaccine

The FDA approved the cholera vaccine in 2016, but it is currently only recommended for adults (ages 18 to 64) who plan to travel to areas where cholera is common or where there are active outbreaks.

The vaccine is given as a single dose and has been shown to reduce the chance of severe diarrhea in adults by 80-90%.

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Watery diarrhea is uncomfortable, but it is a common condition that can often be effectively treated at home without treatment or medication. If the diarrhea lasts more than a couple of days, or 24 hours for babies and young children, or if you show signs of dehydration, you can talk to your doctor or see a doctor as soon as possible.

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