Gastroenteritis (Stomach Flu)

Gastroenteritis, often called stomach flu, is an inflammation of the stomach and intestines. With it, you may have symptoms like diarrhea, vomiting, abdominal cramps and sometimes fever. It often clears up in a few days but sometimes can be more serious or lead to complications. 

Gastroenteritis is highly contagious and almost everyone gets it at least once in their lifetime. It can be caused by viruses, bacteria or parasites.

Viral gastroenteritis

This is the most common type of gastroenteritis. It’s not caused by the influenza virus, even though people call it the stomach flu. The influenza virus affects your nose, throat and lungs. Viral gastroenteritis is caused by viruses like norovirus, rotavirus, adenovirus, astrovirus, calcivirus and sapovirus.

People infected with these viruses can spread them from person to person when they come into contact with surfaces, food or other people and then touch their eyes, nose or mouth. People may be contagious from before symptoms appear until several days after symptoms clear up. 

Bacterial gastroenteritis

Bacteria such as Salmonella, E. coli, C. diff, Campylobacter, Shigella and Staph are often transmitted through contaminated food or water, or through contact with infected people or animals. The contagious period can last for several days to weeks after symptoms subside.

Parasitic gastroenteritis

Parasites like Giardia lamblia or Cryptosporidium can spread through contaminated water or food or poor hygiene. A parasitic infection may last until the parasite is treated.

There are other, less-common causes of gastroenteritis as well, including toxins, chemicals, fungi and some medications.

Stages of gastroenteritis

Gastroenteritis passes through four stages:

• Exposure: You come into contact with the germ. You may not notice you’re sick.
• Incubation: The germ reproduces inside your body.
• Infection: Your immune system fights the infection and you notice symptoms.
• Recovery: Your symptoms clear up and you feel better, although you might still be contagious.

Symptoms of gastroenteritis

With this condition, symptoms often come on suddenly. You may notice:

• Nausea and vomiting
• Diarrhea
• Bloating, abdominal cramps or abdominal pain
• Loss of appetite
• Fever, chills, headaches or body aches
• Fatigue
• Generally, not feeling well
• In some cases, blood or pus in the stool

Who is at risk for gastroenteritis?

Gastroenteritis can affect anyone. You’re at higher risk if you:

• Don’t wash your hands properly after using the bathroom or before handling food.
• Live or work in close quarters, such as nursing homes or childcare facilities.
• Travel to places where food or water is more likely to be contaminated.

People in these groups are at higher risk for severe symptoms and complications:

• Children under five years old since their immune systems are still developing and they don’t always practice good hygiene.
• Adults over 65 years old, who may have weaker immune systems.
• People with conditions such as HIV/AIDS or cancer who are undergoing chemotherapy.
• Women who are pregnant since dehydration can trigger early labor.

How gastroenteritis spreads

You can get gastroenteritis by:

• Eating food or drinking water contaminated with viruses, bacteria or parasites.
• Close contact with an infected person who sheds the virus through stool, vomit or droplets, or through contact with contaminated surfaces.
• Not washing hands thoroughly after using the bathroom or changing diapers (fecal-oral route) or handling food without good hygiene practices.

To help prevent gastroenteritis: 

• Wash fruits and vegetables thoroughly before eating or cooking them.
• Cook meats to proper temperatures to kill bacteria.
• Store food at proper temperatures and keep raw meats separate from other foods.
• Be careful when consuming raw or undercooked foods, especially meats, seafood and eggs. Avoid unpasteurized dairy products and juices.
• Use clean, safe water for drinking and cooking. 
• Clean countertops, faucets, toilets and changing tables frequently.
• Be sure infants get the rotavirus vaccine as part of their routine immunizations. 
• Avoid close contact with other people if you’re sick, especially young children, older adults and people with weaker immune systems.
• Use paper towels to dry your hands if you’re sick.
• Use the high heat setting on your washer and dryer when someone in your household is sick and wash your hands after touching dirty laundry.
• Don’t share utensils, towels or other personal items, especially when you’re sick.
• Always wash your hands thoroughly with soap and water after using the bathroom, changing diapers and before preparing or eating food. Hand sanitizers aren’t as effective against the germs that cause gastroenteritis.
• Drink bottled water and food that’s prepared properly when traveling to places where contamination may be more likely.

Gastroenteritis complications

Many times, you can manage gastroenteritis at home and it usually clears up in a couple of days. But you should watch for these complications:

• Dehydration: Fluid loss from diarrhea and vomiting can lead to dehydration, especially in young children, older adults and people with weakened immune systems. Signs and symptoms of dehydration include thirst, dry mouth, little or no urine or dark urine, dizziness, confusion and fatigue.
• Electrolyte imbalance: When you lose fluids, you also lose electrolytes such as sodium and potassium. This decrease can disrupt your bodily functions.
• Secondary infections: Gastroenteritis can lead to other infections that require more treatment.
• Malnutrition: Diarrhea and vomiting may cause nutrient deficiencies, especially in children and older adults.

Seek medical attention if you’re at high risk for complications or you have:

• Symptoms of dehydration or an inability to keep fluids down
• Vomiting or diarrhea that lasts more than a few days or gets worse, or bloody diarrhea
• Fever for more than three days or fever over 104°F for any length of time (102°F for a child)
• Severe abdominal pain
• Confusion

Diagnosing and treating gastroenteritis

To diagnose gastroenteritis, a health care provider may:

• Perform a physical exam.
• Ask about symptoms, recent travel and possible exposure.
• In some cases, collect a stool sample and test it for viruses, bacteria or parasites.

Your provider may consider whether one of these conditions may be mistaken for gastroenteritis:

• Food poisoning: Food poisoning has similar symptoms to gastroenteritis such as nausea, vomiting and diarrhea, but they often occur more suddenly after eating contaminated food.
• Inflammatory bowel disease (IBD): Conditions like Crohn’s disease and ulcerative colitis cause digestive tract inflammation and symptoms like diarrhea and abdominal pain.
• Irritable bowel syndrome (IBS): IBS can cause symptoms like cramping, abdominal pain and diarrhea, but IBS is a chronic condition that’s not caused by an infection.
• Lactose intolerance: People with lactose intolerance may have diarrhea, gas and bloating after eating dairy products.

If you’re diagnosed with gastroenteritis, treatment depends on the cause:

• Viral gastroenteritis: Rest, hydration and treatment for diarrhea and vomiting. However, talk to a health care provider about how to treat these symptoms, since they may help you get the infection out of your body.
• Bacterial gastroenteritis: Antibiotics may be prescribed. It’s important to complete the full course of antibiotics.
• Parasitic gastroenteritis: Antiparasitic medications.

While you’re sick, you may want to stick to small amounts of bland, easy-to-digest foods like crackers, toast, rice, broth, bananas and applesauce. Ask your provider if oral rehydration solutions or probiotics might help. 

Avoid foods high in fat, sugar, caffeine or dairy, which could make your symptoms worse.

With complications, treatment may include IV fluids for dehydration and electrolyte imbalances or nutrition treatment to give your digestive system time to rest and heal.

Getting care 

You may be able to treat milder cases of gastroenteritis at home with rest, fluids and over-the-counter (OTC) medication for symptoms.

Be sure to see a health care professional if you have vomiting or diarrhea that lasts more than a few days or gets worse or if you’re at high risk for complications.

If you need care, turn to Banner Health. Our experts can get to the root of what’s causing your symptoms and recommend the best treatment options to help speed your recovery.