Symptoms associated with loose, watery stools, also called diarrhea, may include:

• Belly cramps or pain.
• Bloating.
• Nausea.
• Vomiting.
• Fever.
• Blood in the stool.
• Mucus in the stool.
• Urgent need to pass stool.

When to see a doctor

If you're an adult, see your doctor if:

• Your diarrhea doesn't get better or stop after two days.
• You become dehydrated.
• You have terrible abdominal or rectal pain.
• You have bloody or black stools.
• You have a fever above 101 degrees Fahrenheit (38 degrees Celsius).

In children, particularly young children, diarrhea can quickly lead to dehydration. Call your doctor if your child's diarrhea doesn't improve within 24 hours or if your child:

• Becomes dehydrated.
• Has a fever above 101 degrees Fahrenheit (38 degrees Celsius).
• Has bloody or black stools.

A number of diseases and conditions can cause diarrhea, including:

• Viruses. Viruses that can cause diarrhea include Norwalk virus, also known as norovirus, enteric adenoviruses, astrovirus, cytomegalovirus and viruses that cause hepatitis. Rotavirus is a common cause of sudden childhood diarrhea. The virus that causes coronavirus disease 2019 (COVID-19) also has been linked to gastrointestinal symptoms, including nausea, vomiting and diarrhea.
• Bacteria and parasites. Exposure to certain bacteria, such as Escherichia coli, or parasites through contaminated food or water can lead to diarrhea. When traveling in developing countries, diarrhea caused by bacteria or parasites is often called traveler's diarrhea. Clostridioides difficile, also known as C. diff, is another bacterium that causes diarrhea, and it can occur after a course of antibiotics or during a hospital stay.
• Medicines. Many medicines, such as antibiotics, can cause diarrhea. Antibiotics get rid of infections by killing bacteria that cause illness, but they also kill good bacteria that are helpful in the body. This disturbs the natural balance of bacteria in the intestines, leading to diarrhea or an infection such as C. diff. Other medicines that cause diarrhea are anticancer drugs and antacids with magnesium.
• Lactose intolerance. Lactose is a sugar found in milk and other dairy products. People who have trouble digesting lactose often have diarrhea after eating dairy products. Lactose intolerance can increase with age because levels of the enzyme that helps digest lactose become lower as people get older.
• Fructose. Fructose is a sugar found naturally in fruits and honey. It's sometimes added as a sweetener to certain beverages. Fructose can lead to diarrhea in people who have trouble digesting it.
• Artificial sweeteners. Sorbitol, erythritol and mannitol — nonabsorbable sugars used as artificial sweeteners in chewing gum and other sugar-free products — can cause diarrhea in some otherwise healthy people.
• Surgery. Partial intestine or gallbladder removal surgeries can sometimes cause diarrhea.
• Other digestive disorders. Chronic diarrhea has a number of other causes, such as IBS, Crohn's disease, ulcerative colitis, celiac disease, microscopic colitis and small intestinal bacterial overgrowth (SIBO).

Some common risk factors for diarrhea include:

• Exposure to viruses, bacteria or parasites. This is a major risk factor for sudden onset of diarrhea.
• Diet. Certain foods or drinks, including coffee, tea, dairy products, or foods containing artificial sweeteners can cause diarrhea in some people.
• Medicines. Some medicines, such as antibiotics, laxatives, magnesium supplements, antidepressants, NSAIDs, chemotherapy and immunotherapy, can cause diarrhea.

Diarrhea can cause dehydration, which can be life-threatening if not treated. Dehydration is particularly dangerous in children, older adults and those with weakened immune systems.

If you have symptoms of serious dehydration, seek medical help.

Symptoms of dehydration in adults

These include:

• Excessive thirst.
• Dry mouth or skin.
• Little or no urination.
• Weakness, dizziness or lightheadedness.
• Fatigue.
• Dark-colored urine.

Symptoms of dehydration in infants and young children

These include:

• Not having a wet diaper in three or more hours.
• Dry mouth and tongue.
• Fever above 102 degrees Fahrenheit (39 degrees Celsius).
• Crying without tears.
• Drowsiness, unresponsiveness or irritability.
• Sunken appearance to the belly, eyes or cheeks.

Preventing infectious diarrhea

Wash your hands to prevent the spread of infectious diarrhea. To ensure adequate hand-washing:

• Wash frequently. Wash your hands before and after preparing food. And wash your hands after handling uncooked meat, using the toilet, changing diapers, sneezing, coughing or blowing your nose.
• Lather with soap for at least 20 seconds. After putting soap on your hands, rub your hands together for at least 20 seconds. This is about as long as it takes to sing "Happy Birthday" two times.
• Use hand sanitizer when washing isn't possible. Use an alcohol-based hand sanitizer when you can't get to a sink. Apply the hand sanitizer as you would hand lotion, making sure to cover the front and back of both hands. Use a product that contains at least 60% alcohol.

Vaccination

You can help protect your infant from rotavirus, the most common cause of viral diarrhea in children, with one of two approved vaccines. Ask your baby's doctor about having your baby vaccinated.

Preventing traveler's diarrhea

Diarrhea commonly affects people who travel to countries with poor sanitation and contaminated food. To reduce your risk:

• Watch what you eat. Eat hot, well-cooked foods. Don't eat raw fruits and vegetables unless you can peel them yourself. Don't eat raw or undercooked meats and dairy foods.

• Watch what you drink. Drink bottled water, soda, beer or wine served in its original container. Don't drink tap water or use ice cubes. Use bottled water even for brushing your teeth. Keep your mouth closed while you shower.

  Beverages made with boiled water, such as coffee and tea, are probably safe. Remember that alcohol and caffeine can aggravate diarrhea and worsen dehydration.

• Ask your health care team about antibiotics. If you're traveling to a developing country for an extended time, ask a member of your healthcare team about getting antibiotics before you go, especially if you have a weakened immune system.
• Check for travel warnings. The Centers for Disease Control and Prevention maintains a travelers' health website where disease warnings are posted for various countries. If you're planning to travel outside of the United States, check there for warnings and tips for reducing your risk.

Your healthcare professional will likely ask about your medical history, review the medicines you take and conduct a physical exam. Your health professional may order tests to determine what's causing your diarrhea. Possible tests include:

• Blood tests. A complete blood count, measurement of electrolytes and tests of kidney function can help indicate how bad your diarrhea is.
• Stool test. You may have a stool test to see if a bacterium or parasite is causing your diarrhea.
• Hydrogen breath test. This type of test can help determine if you have a lactose intolerance. After you drink a liquid that contains high levels of lactose, your breath is measured for hydrogen at regular intervals. Breathing out too much hydrogen indicates that you aren't fully digesting and absorbing lactose.
• Flexible sigmoidoscopy or colonoscopy. Using a thin, lighted tube that's inserted into the rectum, a medical professional can see inside of the colon. The device also has a tool that allows the doctor to take a small sample of tissue, called a biopsy, from the colon. Flexible sigmoidoscopy provides a view of the lower colon, while colonoscopy allows the doctor to see the entire colon.
• Upper endoscopy. A medical professional uses a long, thin tube with a camera on the end to examine the stomach and upper small intestine. They may remove a tissue sample to be checked in a laboratory.

Most cases of sudden diarrhea clear on their own within a couple of days without treatment. If you've tried lifestyle changes and home remedies for diarrhea without success, your healthcare professional might recommend medicines or other treatments.

Antibiotics or antiparasitics

Antibiotics or antiparasitic medicines might help treat diarrhea caused by certain bacteria or parasites. Most bacterial causes of diarrhea do not need treatment in most people. If a virus is causing your diarrhea, antibiotics won't help.

Treatment to replace fluids

Your healthcare professional likely will advise you to replace the fluids and salts that you lose when you have diarrhea. For most adults, that means drinking water with electrolytes, juice or broth. If drinking liquids upsets your stomach or causes vomiting, your healthcare professional might give you IV fluids.

Water is a good way to replace fluids, but it doesn't contain the salts and electrolytes — minerals such as sodium and potassium — that your body needs to function. You can help maintain your electrolyte levels by drinking fruit juices for potassium or eating soups for sodium. But certain fruit juices, such as apple juice, might make diarrhea worse.

For children, ask your doctor about using an oral rehydration solution, such as Pedialyte, to prevent dehydration or replace lost fluids.

Adjusting medicines you're taking

If your healthcare professional determines that an antibiotic caused your diarrhea, you might be given a lower dose or a different medicine.

Treating underlying conditions

If your diarrhea is caused by a more serious condition, such as inflammatory bowel disease, your healthcare professional works to control that condition. You might be referred to a specialist, such as a gastroenterologist, who can help devise a treatment plan for you.

Diarrhea usually clears up quickly without treatment. To help you cope with your symptoms until the diarrhea goes away, try to do the following:

• Drink plenty of liquids, including water, broths and juices. Avoid caffeine and alcohol.
• Add semisolid and low-fiber foods gradually as your stool returns to what's typical for you. Try soda crackers, toast, eggs, rice or chicken.
• Don't eat certain foods such as dairy products, fatty foods, high-fiber foods or highly seasoned foods for a few days.

• Ask about antidiarrheal medicines. Nonprescription antidiarrheal medicines, such as loperamide and bismuth subsalicylate, might help reduce how often you pass watery stool and control severe symptoms.

  Certain medical conditions and infections — bacterial and parasitic — can be worsened by these medicines because they prevent your body from getting rid of what's causing the diarrhea. Some of these medicines are not recommended for children. Check with your healthcare professional before taking these medicines or giving them to a child.

• Take probiotics. These microorganisms may help restore a healthy balance to the intestinal tract by boosting the level of good bacteria. However, it's not clear if they can help shorten a bout of diarrhea. Probiotics are available in capsule or liquid form and are also added to some foods, such as certain brands of yogurt. Further research is needed to better understand which strains of bacteria are most helpful and what doses are needed.

You might start by seeing a member of your primary healthcare team. If you have lasting diarrhea, you may be referred to a doctor who specializes in the digestive system, called a gastroenterologist.

Here's some information to help you get ready for your appointment.

What you can do

When you make the appointment, ask if there's anything you need to do in advance, such as fast before certain tests. Make a list of:

• Your symptoms, including when they began and any that may seem unrelated to the reason for your appointment.
• Key personal information, including any major stresses, recent life changes or travel.
• Medicines, vitamins or supplements you take, including doses. If you've recently taken an antibiotic, note what kind, for how long and when you stopped.
• Questions to ask your healthcare professional.

For diarrhea, some basic questions to ask include:

• What is likely causing my diarrhea?
• Could my diarrhea be caused by a medicine I'm taking?
• What tests do I need?
• Is my diarrhea likely short-term or long lasting?
• What is the best course of action?
• What are the alternatives to the primary approach that you're suggesting?
• I have other health conditions. How can I best manage them with the diarrhea?
• Are there restrictions I should follow?
• May I take medicine such as loperamide to slow down the diarrhea?
• Should I see a specialist?

Don't hesitate to ask other questions.

What to expect from your doctor

Your healthcare professional is likely to ask you questions, including:

• When did your symptoms begin?
• Do your symptoms happen all the time or only sometimes?
• How bad are your symptoms?
• What, if anything, seems to make your symptoms better?
• What, if anything, appears to make your symptoms worse?
• Does your diarrhea awaken you at night?
• Do you see blood in your stool, or are your stools black?
• Have you recently been around anyone who has diarrhea?
• Have you recently stayed in a hospital or nursing home?
• Have you taken antibiotics recently?

What you can do in the meantime

While you wait for your appointment, you may ease your symptoms if you:

• Drink more fluids. To help avoid dehydration, drink water, juice and broth.
• Don't eat foods that can aggravate diarrhea. Stay away from fatty, high-fiber or highly seasoned foods.