Causes of Watery Diarrhea—and What You Can Do About It (2024)

Watery diarrhea means that you have liquid stools. Causes include viral infections, like norovirus, and bacterial infections, like Clostridioides difficile. Medical conditions like celiac disease and irritable bowel syndrome (IBS) can also cause watery diarrhea.

Some cases of watery diarrhea are self-limiting or don't require treatment. However, if watery diarrhea is persistent and left untreated, it can lead to dehydration and potentially serious complications like seizures and shock. Infants and young children are at high risk due to their small body size.

This article explains the causes and symptoms of watery diarrhea as well as how diarrheal diseases are diagnosed and treated.

What Are the Symptoms of Watery Diarrhea?

Watery diarrhea means your stools are liquid instead of firm. They occur in episodes at least three times a day, often with an explosive rush of watery stool. Sometimes, there is a complete lack of control over your bowel movements.

Depending on the cause, the frequency, severity, duration, and even the color of the diarrhea can vary. For instance, bouts of watery yellow diarrhea every 20 minutes or so are signs of a parasitic infection known as giardiasis.

Diarrhea can coincide with other symptoms, such as:

• Nausea
• Vomiting
• Loss of appetite
• Cramping
• Fever
• Blood in stool

What Are Complications of Watery Diarrhea?

Watery diarrhea is often harmless and fleeting. But, in some cases, it can lead to serious complications like dehydration and malabsorption.

Dehydration

The human body mostly consists of water that it needs to function properly. Dehydration occurs when it doesn’t have enough water, causing body systems to malfunction or fail.

Signs and symptoms of dehydration include:

• Thirst
• Dark yellow or brown urine
• Infrequent urination
• Fatigue
• Dry mouth
• Lack of tears when crying (especially in young children and babies)
• Dry, loose skin
• Sunken eyes or cheeks
• Feeling lightheaded or fainting

When you have watery diarrhea, it can be easy for your body to lose more fluids than it takes in. Dehydration can be especially dangerous for small children whose body volumes are small.

The excessive loss of body fluids can lead to serious and potentially life-threatening complications like seizures, kidney failure, and hypovolemic shock.

Malabsorption

Malabsorption happens when your body doesn’t absorb enough of the nutrients it needs from the foods you eat. This can lead to malnourishment and malnutrition.

Diarrhea doesn’t necessarily cause this problem. Some of the infections that cause diarrhea, such as parasites, disrupt the body’s ability to digest food properly and absorb the nutrients it needs.

Signs and symptoms of malabsorption include:

• Abdominal pain
• Bloating and gas
• Changes in appetite
• Unintended weight loss

What Causes Watery Diarrhea?

There are quite a few germs that can cause watery diarrhea, many of which are spread through contaminated food, water, or hand-to-mouth behaviors. There are also certain diseases and health conditions that cause watery diarrhea.

Viral Causes

Viral gastroenteritis occurs when certain viruses infect the digestive tract and cause "stomach flu." This leads to watery diarrhea along with cramping and nausea.

There is no specific treatment for these gastrointestinal viruses. They often run their course without the need for medicine.

The most common cause of viral gastroenteritis are:

• Rotavirus: This is the most common cause of diarrhea in the world. It accounts for 40% of diarrhea-related hospitalizations in young children.
• Norovirus: This is the most common foodborne disease in the United States. Roughly 400,000 emergency room visits every year are due to norovirus, mostly in young children.
• Astroviruses: This most commonly affects young kids and adults with weakened immune systems. Most cases are relatively mild and clear up on their own within a few days.
• Adenoviruses: These viruses are commonly associated with the common cold and conjunctivitis (pink eye). Certain types can also cause diarrhea lasting up to two weeks.
  

Bacterial Causes

There are several types of bacterial infections associated with watery diarrhea. Most are foodborne and spread through contaminated food or improper hygiene.

Campylobacter

Campylobacter is a common cause of foodborne illness in the United States, causing an estimated 1.3 million acute infections each year. The bacteria are spread primarily through undercooked poultry but can also be found in unpasteurized milk and contaminated water.

Most people with a campylobacter infection don’t need treatment. The illness will eventually clear up on its own.

Escherichia coli (E. coli)

E. coli is a group of bacteria that can cause a wide range of symptoms. Some strains cause diarrhea, vomiting, and abdominal pain, while others cause respiratory illnesses or urinary tract infections.

Shiga toxin-producing E. coli (STEC) is the type that causes watery (and sometimes bloody) diarrhea. It is spread through contaminated food or drinks. Common sources of infection include raw or undercooked ground meat, raw vegetables, and sprouts.

Salmonella

Salmonella infections are predominantly linked to contaminated food. This bacteria is found in a wide range of raw and processed foods, including sprouts, nut butter, and processed chicken nuggets.

Salmonella also can be spread from animals to people. In early 2019, the Centers for Disease Control and Prevention (CDC) reported a multi-state salmonella outbreak linked to pet hedgehogs.

Shigella

People with shigellosis usually start feeling sick a day or two after eating food contaminated with the Shigella bacteria. This includes foods like salads, raw vegetables, and dairy products. It is also possible to get Shigella through sexual contact with someone who was recently infected.

Shigellosis usually causes watery diarrhea for around a week, but it can sometimes take months for bowel movements to return fully back to normal.

Kids are the most likely to get shigellosis than adults. Other groups at increased risk include travelers, men who have sex with men, and people with weakened immune systems.

Clostridioides Difficile

Most healthy people exposed to this bacteria, commonly known as C. difficile, don't get sick. It is only when they take antibiotics that C. difficile can proliferate and cause an infection while other "good" bacteria are killed by the antibiotics.

According to the CDC, the risk of C. difficile increases by seven- to ten-fold when taking antibiotics. The risk of C, difficile is highest in medical settings such as hospitals or long-term care facilities.

The CDC estimates that nearly half a million infections and 15,000 deaths in the United States are caused by C. difficile each year.

Cholera

Cholera is rarely seen in the United States. Outbreaks are mainly confined to developing countries where sanitation, clean water, and community healthcare are often in short supply.

Most people who get cholera won’t have any symptoms. Even so, they can spread the bacteria to other people through the fecal-oral route. This is when you fail to wash your hand after going to the bathroom or touching surfaces contaminated with poop.

When symptoms occur, watery diarrhea is characteristic. It is often referred to as “rice water stools” because it looks like the water left after washing rice. Vomiting and cramps also are common.

Globally, an estimated 1.3 to 4 million cases of cholera occur every year, causing between 21,000 and 143,000 deaths. Death can occur within hours due to severe dehydration.

Parasitic Causes

Parasitic gastrointestinal infections are most common in areas with poor access to clean water and sanitation. There are many different types of parasites that can lead to watery diarrhea, some of which are common even in the United States.

Cryptosporidiosis

Cryptosporidiosis, or “crypto,” is caused by a microscopic parasite that infects the intestines. These parasites have a tough outer shell that protects them from disinfectants, including bleach. This is why cases of crypto are still fairly common in the United States.

Crypto is common in toddlers who attend daycare. It can also affect people who travel abroad or those who swim in (or drink) contaminated water from streams or lakes.

Cyclosporiasis

Cyclosporiasis is caused by a parasite called Cyclospora cayetanensis and is transmitted by the fecal-oral route. You most often get it by eating contaminated food or drinking contaminated water.

The microscopic parasite can cause frequent and sometimes explosive diarrhea. Symptoms can last anywhere from a few days to more than a month. Symptoms can also go away and come back several times if the infection is left untreated.

Giardia

Giardiasis is an infection of the small intestine caused by the parasite Giardia lamblia. It is most often transmitted through contaminated water and poor hygiene.

Many cases are asymptomatic (without symptoms), but the parasite can still be passed through the fecal-oral route. When symptoms develop, watery, foul-smelling diarrhea is the most common symptom. Gas, bloating, and stomach cramps are also common.

Other Causes

Infectious diseases are the most common cause of watery diarrhea, but some non-infectious causes can lead to frequent bouts of diarrhea as well.

These include:

• Lactose intolerance
• Celiac disease
• Inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis
• Irritable bowel syndrome (IBS)

How Is Watery Diarrhea Diagnosed?

Few people need a healthcare provider to diagnose watery diarrhea. The symptom is pretty self-evident.

However, if the condition doesn’t improve after a couple of days—or you or your child are exhibiting signs of dehydration—your healthcare provider may want to run tests. This will help them pinpoint the exact cause so that it can be treated effectively.

Physical Exam

Before running tests, your healthcare provider will want to do a physical exam. They will start by checking your blood pressure, pulse, and temperature to rule out any signs of serious dehydration.

They might also use a stethoscope to listen for bowel sounds or lightly press (palpate) your abdomen to check tenderness, pain, or signs of swelling.

Your healthcare provider will also ask questions to get more information about your symptoms, like:

• How long have you been having watery diarrhea?
• How often do you need to use the bathroom?
• Did you eat something, go somewhere, or do something different prior to getting diarrhea?
• Have you traveled overseas recently?
• Are you taking any new medications?
• Are you having any pain and, if so, where?
• Do you have other symptoms, like nausea or fever?

Diagnostic Tests

Based on the initial findings, some of the following tests may be ordered:

• Stool test: This test checks stool samples for evidence of bacteria or parasites or signs of blood, pus, or bile. It is the most common starting point in the investigation.
• Blood tests: This includes a complete blood count (CBC) to check for signs of infection and disease-specific tests for conditions like celiac disease.
• Hydrogen breath test: This is used to diagnose lactose intolerance. It is done by drinking a solution containing lactose and then breathing into a device that measures hydrogen levels. A high level indicates lactose intolerance.
• Elimination diet: This helps you to identify which foods are causing diarrhea if you have IBS. You start by eliminating suspected foods (like dairy or wheat) to see if your diarrhea stops. The foods are then reintroduced one by one to see if any cause diarrhea.
• Endoscopy: For an upper endoscopy, the flexible scope is threaded into the mouth to view the stomach and small intestine. For a colonoscopy, a flexible scope is threaded through the anus to view the rectum and large intestine.

How Is Watery Diarrhea Treated?

The treatment of watery diarrhea is focused on resolving the root cause, often with medications that ease the severity of diarrhea. Imodium (loperamide) is one anti-diarrheal drug available over the counter.

If the illness is caused by bacteria, antibiotics can be used to treat the infection. If the symptoms are caused by a parasite, an antiparasitic drug may be used. Viral causes usually resolve on their own.

Replace Lost Fluids

It's important to replace lost fluids to avoid dehydration. This can be a problem since gastroenteritis often causes nausea and vomiting. You can overcome this by taking tiny sips rather than big gulps.

If you are unable to hydrate and your symptoms worsen, you may need to go to a hospital to get intravenous (IV) fluids delivered into your vein, The hospital can also prescribe antiemetic drugs to ease nausea and vomiting.

What to Drink When You Have Watery Diarrhea

Water should be your primary drink to treat dehydration. But you should also address potential electrolyte imbalances caused by watery diarrhea.

Electrolytes are charged particles, like sodium and potassium, that help regulate body functions like heartbeats and respiration. They are found in a wide variety of foods, but one of the fastest ways to get them is through beverages that contain a small amount of salt.

Sports drinks and special hydration fluids like Pedialyte work well. Or, you can make your own by adding a small amount of salt and sugar to a glass of lemon water.

What Not to Drink When You Have Watery Diarrhea

Caffeinated and alcoholic beverages should be avoided if you have diarrhea. They both have diuretic effects that make you urinate more and accelerate fluid loss.

Caffeine is not only found in coffee and colas but also in sports drinks, energy drinks, chocolate, black tea, green tea, and cocoa.

How to Prevent Watery Diarrhea

Watery diarrhea can be avoided by taking certain precautions. These include washing your hands frequently, ensuring food safety, and getting certain vaccinations.

Improved Hygiene

Most germs that cause watery diarrhea are spread through contaminated food and water. This is often caused by unhygienic practices.

The best way to avoid infectionsis to wash your hands after using the bathroom and handling food. You need to take extra care when traveling abroad, only drinking bottled water, only eating well-cooked foods, and avoiding swimming in unchlorinated water.

Food Safety

Some infections that cause watery diarrhea are caused by foods that haven’t been prepared, stored, or handled properly.

To reduce your risk:

• Wash your hands before and after handling food.
• Keep your fresh produce away from raw meats.
• Cook meats thoroughly.
• Store any prepared foods at proper temperatures.

Vaccination

Two common causes of diarrhea, rotavirus and cholera, can be prevented through vaccination.

Rotavirus Vaccine

Rotavirus vaccination is part of the routine childhood vaccinations recommended by the CDC. It’s given orally in two or three doses (depending on the brand) starting at 2 months of age.

Currently, in the United States, only about 73% of kids ages 19 to 35 months received a rotavirus vaccine compared to 91.5% who were vaccinated against measles.

Cholera Vaccine

The Food and Drug Administration (FDA) approved a cholera vaccine in 2016. It has been shown to lower the chances of getting severe diarrhea in adults with cholera by 80% to 90%.

It is currently only recommended for adults ages 18 to 64 who are planning to travel to places where cholera is common. Most travelers do not need the vaccine.

Summary

There are many reasons for watery diarrhea, including viral, bacterial, and parasitic infections as well as medical conditions such as irritable bowel syndrome (IBS), celiac disease, and inflammatory bowel disease (IBD).

In addition to treating the underlying cause of watery diarrhea, you need to replace the lost fluids to avoid dehydration and other potentially severe complications. Seek immediate care if you have signs of severe dehydration such as sunken eyes, fatigue, increased thirst, and lightheadedness,