Stomach flu is not a flu at all. It is usually a viral illness called gastroenteritis. Stomach flu is most often caused by a virus, but bacteria and parasites may also cause it.
Stomach flu symptoms cause nausea, diarrhea, and sometimes vomiting. The illness may also cause a headache, chills, fever, and abdominal pain. Viral gastroenteritis symptoms typically come on approximately 12 to 48 hours after you are exposed to the virus and last for 1 to 3 days. Stomach flu caused by bacteria or parasites may last longer. Stomach flu can be dangerous for people who have underlying health conditions, babies, and the elderly.
Viral gastroenteritis causes infection and inflammation of the stomach lining and intestines. Stomach flu is contagious. You can get it easily by touching someone who is infected or touching an object that has come into contact with an infected person. Eating food prepared by someone who has viral gastroenteritis can make you sick. Contaminated shellfish can harbor gastroenteritis. The virus can live in contaminated water, so eating fruits and vegetables washed in contaminated water can make you sick.
There are four different viruses that cause gastroenteritis. The most common cause of stomach flu in kids and infants is rotavirus. Adults can get rotavirus too, but the condition tends to be milder. A virus called norovirus is the most common cause of viral gastroenteritis in adults. Adenovirus and astrovirus are less common causes of viral gastroenteritis that occur more often in kids than adults.
The stomach virus incubation period ranges from 12 hours to 10 days depending on the type of virus. How long does stomach flu last? Again, that depends on the type of virus, but it ranges from 1 day to 2 weeks.
Food poisoning vs stomach flu: What's the difference? The symptoms of both illnesses may be the same, including fever, diarrhea, and vomiting. But food poisoning tends to come on faster than the stomach flu. Bacteria like Salmonella and E. coli may produce food poisoning from bacterial gastroenteritis. Where does the bacteria come from? Bacteria may multiply at any point during the food production process from harvesting to preparation. Bacteria may grow when food is stored, shipped, or processed. It may also reside on utensils and surfaces in the kitchen.
Bacteria flourish and multiply between 40 and 140 degrees F. So make sure to set your refrigerator to below 40 degrees F to keep cold food cold. The opposite is true, too. Keep hot foods hot before consuming. Foods that should be kept in the refrigerator or freezer will start to grow bacteria if they sit around long enough at room temperature. If you consume foods that contain harmful bacteria, you may get food poisoning.
So-called traveler's diarrhea is gastroenteritis that occurs due to contaminated food or water. You can get traveler's diarrhea anywhere but you're more likely to get it traveling to developing countries in Asia, the Middle East, Central America, South America, Africa, the Caribbean, and Mexico. People get sick by eating contaminated or undercooked shellfish, meat, fish, and raw fruits and vegetables that may have been washed in contaminated water. Street food is another type of food that may make you sick. Drink bottled water and use bottled water to brush your teeth. Do not drink beverages that have ice. The duration of stomach flu due to traveler's diarrhea depends on what kind of microorganism is causing the infection.
If the infections are not treated:
- Bacteria diarrhea lasts approximately 3 to 7 days
- Viral diarrhea lasts approximately 2 to 3 days
- Protozoal diarrhea lasts approximately weeks to months
Parasites are small microorganisms that rely on animals or people for their survival. These infections are uncommon in the US and Western countries. Parasitic organisms including Giardia and Cryptosporidium parvum are spread through contaminated water. Eating food washed with contaminated water can make you sick as can drinking or swimming in water containing parasites.
Gastroenteritis tends to resolve on its own within a few days. Just rest and drink lots of fluids. If you do not feel better within a few days, see your doctor. You make need medication like antibiotics for a bacterial infection or antiparasitic medication if you have a protozoal infection. The doctor may perform tests to determine what is causing your symptoms.
There are at home stomach flu remedies you can use to help ease symptoms. If you don't feel like eating, it's still important to take in adequate fluids, electrolytes, calories, and nutrition. You can accomplish this by sipping fruit juice, soft drinks without caffeine, sports drinks, and electrolyte drinks. Broth works, too. When you are ready for solid foods, stick to the BRAT diet and have some bananas, rice, applesauce, and toast. You can try potatoes as well. Steer clear of dairy, sugary foods, alcohol, and caffeine, as these may worsen your symptoms.
When considering what helps stomach flu, hydration is one of the top interventions to feel better. Vomiting and diarrhea lead to a loss of water, and dehydration may result. It can be dangerous for elderly people, babies, and those who have underlying health conditions. Dehydration signs include dark urine, fatigue, severe thirst, and dizziness. Sunken eyes and cheeks and dry mouth are other signs of dehydration.
Rehydration is important if you or your child get a stomach flu. Sports drinks, clear soups or broths, and juice supply water, nutrients, and electrolytes. You can use popsicles and ice chips, too. Go to the ER right away if you or your child experience dizziness, racing heart rate, or cannot keep fluids down. These are signs of severe dehydration, and you need intravenous (IV) rehydration at the hospital.
A rare complication of gastroenteritis is called hemolytic uremic syndrome, which results in the destruction of red blood cells and platelets due to E. coli infection. This complication is most likely to occur in children under the age of 10 years. The condition may cause kidney failure and can adversely affect the nervous system. Signs and symptoms include blood in the stool, cranky mood, infrequent urination, and pale skin. If you or your child develop these symptoms, see your doctor right away or go to the emergency room.
Some symptoms of gastroenteritis are bad enough that you should seek medical attention if you develop them. These include:
- Persistent vomiting/inability to keep down liquids for more than 24 hours
- Persistent diarrhea for 24 hours for children or a couple of days for adults
- Fever 101 degrees F or higher
- Blood in stool, black stool, pus in stool
- Nervous system issues including loss of balance or coordination/numbness
- Severe GI or rectal pain
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- CDC: "About Parasites," "Parasites," "Travelers' Diarrhea."
- CDC Yellow Book: “Traveler’s Diarrhea.”
- KidsHealth.org: “Dehydration.”
- Mayo Clinic: "Dehydration," “Viral Gastroenteritis (Stomach Flu).”
- Merck Manual: “Gastroenteritis.”
- National Institute of Diabetes and Digestive and Kidney Diseases: "Foodborne Illnesses," “Hemolytic Uremic Syndrome in Children,” "“Treatment of Viral Gastroenteritis ('Stomach Flu')," "Viral Gastroenteritis ('Stomach Flu')."
- National Institutes of Health: “Gastroenteritis,” “Foodborne Illnesses,” “Viral Gastroenteritis.”