What Is Gastroenteritis? Symptoms, Causes, Diagnosis, Treatment, and Prevention

Gastroenteritis is often called the “stomach flu,” even though it’s not a type of flu at all. Instead, it’s inflammation of the lining of your intestines.

Most of the time a virus is the culprit, in which case the illness is known as viral gastroenteritis.

Occasionally, bacteria, parasites, or other causes may trigger gastroenteritis, according to the Merck Manual. (1)

Avoiding contaminated food and water, along with frequent hand-washing, may help protect you from this unwelcome condition.

Types of Gastroenteritis

In the United States, viruses are the most common reason for gastroenteritis. (1) Many viruses can cause gastroenteritis, including:

Norovirus Norovirus affects both children and adults and is the most common cause of foodborne illness in the world, according to the Mayo Clinic. (2) Most of the time, this virus is passed on through contaminated water or food. It spreads quickly, especially among people in confined spaces. You may have heard about the norovirus affecting passengers on cruise ships. Outbreaks are also common in nursing homes and other places where people are in close contact with one another. Symptoms usually last one to three days. (1,3)

Rotavirus This is the most common cause of viral gastroenteritis in children. (2) It frequently affects babies between 3 and 15 months old. Symptoms last from three to seven days. The virus is usually less severe when it impacts adults. There’s a vaccine available in the United States to protect against rotavirus. Since this vaccine has been introduced, cases of rotavirus have been reduced by about 80 percent. (1,3)

Adenovirus This virus most often affects children under age 2. The symptoms may last 5 to 12 days. (3)

Astrovirus Infants and young children are more likely to get astrovirus, but it can infect anyone. It’s typically spread by the fecal-oral route and lasts about three to four days. (1)

Gastroenteritis that isn’t caused by a virus may be due to:

Bacteria Salmonella, shigella, campylobacter, Clostridium difficile (C. difficile), and Escherichia coli (E. coli) infections sometimes lead to gastroenteritis. These bacteria can spread by consuming contaminated food or water. (1)

Parasites Most cases of parasitic gastroenteritis are caused by giardia and cryptosporidium, per the Medical University of South Carolina. (4) These organisms can be picked up by drinking contaminated water or swimming in a contaminated pool.

Other causes Ingesting certain drugs or chemical toxins, such as metals or plant substances, can lead to gastroenteritis, although this is rare. (1)

Symptoms of gastroenteritis usually start about one to two days after a virus enters your body, and may include: (3)

• Watery diarrhea
• Stomach pain or cramps
• Nausea
• Vomiting
• Muscle aches
• Headache
• Fever
• Chills

Typically, these symptoms last a day or two, but they can persist for up to 10 days. (2,3)

In some people, symptoms of gastroenteritis get worse at night. This happens because your immune system often gets more active at night, and releases infection-fighting substances that cause inflammation and make you feel worse, according to the Cleveland Clinic. (5)

Can You Have a Stomach Virus Without Vomiting or Diarrhea?

Gastroenteritis can cause a wide range of symptoms, from mild stomach upset to severe vomiting and diarrhea. Some people even catch, and can spread, the viruses that commonly cause gastroenteritis without showing any symptoms at all. (5)

Doctors typically diagnose gastroenteritis by inquiring about your symptoms and performing a physical exam.

Your healthcare provider might ask you questions such as:

• When did your symptoms start?
• Have your symptoms been constant, or do they start and stop?
• How severe are your symptoms?
• Does anything you do seem to improve or worsen your symptoms?
• Do you have any signs of dehydration?
• Have you been in contact with other people who have the same symptoms as you?

Your doctor might also order a rapid stool test to see if you have norovirus or rotavirus. Additionally, you might be asked to provide a stool sample to detect a bacterial or parasitic infection. (2)

Sometimes, doctors order tests to look for signs of other illnesses that may cause symptoms similar to those of gastroenteritis, including inflammatory bowel disease (IBD). (5)

Gastroenteritis will usually run its course and go away on its own. There’s no specific medical treatment for viral gastroenteritis.

If you have a bacterial infection, your doctor might prescribe antibiotics. (1,2)

Physicians usually don’t suggest that you take antidiarrheal treatments because they can prolong the infection, especially in children. But these medicines may be beneficial in some cases. (1)

More on Digestive Health

3 Ways to Treat Diarrhea

When Should You See a Doctor for Gastroenteritis?

Determining when you should see a doctor for your gastroenteritis depends on your age.

For adults, you should see a doctor if you:

• Have a fever higher than 104 degrees F
• Can’t keep liquids down for 24 hours
• Have been vomiting blood or have been vomiting for more than two days
• Have bloody bowel movements
• Have signs of dehydration, such as decreased urination, dark-colored urine, dry skin, thirst, or dizziness (2)

For babies and children, you should see a doctor if your child:

• Has a fever of 102 degrees F or higher
• Seems to be in pain or discomfort
• Has bloody or severe diarrhea
• Has signs of dehydration, such as dry diapers, lack of tears when crying, dry mouth, drowsiness, or a sunken fontanel
• Has vomiting that lasts more than several hours
• Is unusually irritable, lethargic, or unresponsive (2)

Self-Care for Gastroenteritis

Certain steps can help improve symptoms of gastroenteritis and prevent dehydration. You might want to try:

Letting Your Stomach Settle Taking a break from eating solid foods for a few hours at a time may alleviate your stomach troubles.

Avoiding Certain Foods and Substances Stay away from caffeine; alcohol; dairy products; and fatty, sugary, or spicy foods until you start to feel better.

Eating Bland Foods Plain foods are less likely to irritate your digestive system. Crackers, toast, bananas, gelatin, rice, potatoes, and chicken are some good choices.

Staying Hydrated Try to drink plenty of liquids. You might want to suck on ice chips or take small sips of water. Clear sodas, broths, and noncaffeinated sports drinks can keep you hydrated. Children might need an oral rehydration solution, which is available at most pharmacies, according to American Family Physician. (7) If you’re breastfeeding or formula-feeding a baby, continue to feed the child as usual.

Getting Lots of Rest Gastroenteritis can zap your energy. Be sure to rest when you can and get a good night’s sleep. (2)

Prevention of Gastroenteritis

Certain precautions may lower your chances of getting gastroenteritis. These include the following:

Wash your hands often. Proper hygiene, which consists of frequent hand-washing, is one of the best ways to avoid catching a virus. Wash your hands for at least 20 seconds with soap and water after you go to the bathroom and before you eat or prepare food. Be sure to wash around your cuticles, under your fingernails, and in the creases of your hands. Also, teach your kids to wash their hands after using the toilet.

More on Prevention

Why Proper Hand-Washing Is Essential During Cold and Flu Season

Sanitize. Use an alcohol-based hand sanitizer or wipe if you can’t wash your hands.

Keep areas clean. If someone you’re living with has gastroenteritis, be sure to disinfect all surfaces with a bleach-based cleanser. Try using a ratio of 2 cups of bleach to 1 gallon of water.

Avoid contaminated foods or water. Don’t eat or drink any foods that may make you sick, such as raw or undercooked meats. Consume only pasteurized dairy products and apple juice. Rinse all produce well before preparing or eating it.

Don’t share personal items. Avoid drinking from the same glass, can, or bottle as others and sharing utensils or towels.

Stay away from others. If people you know are sick, try to keep your distance from them. If you’re sick, stay away from people, and don’t prepare food for anyone while you’re sick or for two days afterward.

Vaccinate children. A vaccine is available in some countries, such as the United States, to protect babies from rotavirus. It’s typically administered during a baby’s first year of life.

Examine your child’s day care facility. Make sure the center has separate diaper-changing and eating areas. There should also be a sink to wash hands near the changing table. (2,5)

Tips to Prevent Gastroenteritis While Traveling

Many people develop gastroenteritis when they visit other countries. This usually happens because they drink unclean water or eat contaminated foods. This is commonly called traveler's diarrhea.

When you’re traveling, use sealed, bottled water to drink and brush your teeth. Avoid ice cubes, as they can contain contaminated water.

Be sure to wash or sanitize your hands often while you’re out and about.

Also, play it safe when it comes to the foods you eat. It’s a good idea to avoid raw foods, such as veggies, peeled fruits, and salads. Steer clear of undercooked meat and fish, too. (2)

Norovirus is estimated to cause between 19 and 21 million cases of viral gastroenteritis each year in the United States. (6) Data on other, less common types of gastroenteritis isn’t readily available.

Worldwide, severe gastroenteritis is believed to cause over one million deaths each year. About one-half of these deaths occur in children. (1)

Dealing with gastroenteritis can be scary and difficult, and you may want to look for other sources of information and support. The following resources may help:

• Foodborne Germs and Illnesses, Centers for Disease Control and Prevention (CDC)
• Norovirus, CDC
• Food Safety Charts, FoodSafety.gov
• Stomach flu: How Long Am I Contagious? Mayo Clinic

Questions to Ask Your Doctor About Gastroenteritis

You might want to bring a list of questions to your or your child’s appointment. Some questions to ask your doctor include: (2)

• What’s causing my symptoms?
• Do I need any tests to confirm my diagnosis?
• What types of measures should I take to avoid spreading this illness?
• What treatments are available? Are there alternative approaches?
• How long will my symptoms last?
• What can I do at home to improve my symptoms?

Gastrointestinal symptoms occur in many people who develop COVID-19 — the disease caused by the novel coronavirus SARS-CoV-2 — although they don’t affect everyone with the viral infection. These symptoms may include nausea, vomiting, and diarrhea, and sometimes develop before the onset of fever or respiratory symptoms, per the CDC. (10)

If you develop gastrointestinal symptoms followed by respiratory symptoms, contact your doctor to discuss whether you need to be tested for COVID-19. Follow your doctor’s advice and other guidelines to ensure that you don’t spread the virus to other people, notes the CDC. (11)