People who have the 24-hour flu are actually experiencing a condition known as gastroenteritis, also often referred to as stomach flu.

Gastroenteritis is commonly known as the 24-hour flu because the symptoms it causes may only last a day or two. That’s not always true, though, since GI issues caused by this condition can sometimes take up to 14 days to go away, notes Dr. Bellos. Gastroenteritis is an inflammation of the lining of the stomach and intestines, which leads to symptoms such as vomiting and diarrhoea. Although gastroenteritis can be caused by viral, bacterial, or parasitic infections, viral gastroenteritis is typically responsible for many cases of 24-hour flu. Despite the “24-hour” moniker, viral gastroenteritis symptoms can last between 24 and 72 hours. Read on to learn more about the 24-hour flu, including symptoms, home remedies, and when to see a doctor.

The symptoms of 24-hour flu typically appear one to three days after you’ve been infected and can include:

• Diarrhoea
• nausea or vomiting
• abdominal cramps or pain
• loss of appetite
• low-grade fever
• body aches and pains
• headache
• feeling tired or fatigued

Most people with 24-hour flu notice that their symptoms begin to disappear within a few days.

The 24-hour flu is very contagious, meaning that it can spread easily from person-to-person. You can become infected in the following ways:

• Having close contact with a person who has the infection.
• Coming into contact with a surface or object that’s been contaminated. Examples include things like doorknobs, faucets, or eating utensils.
• Consuming contaminated food or water.
• If you develop symptoms, wash your hands frequently, especially after using the bathroom and before handling food.

Since the illness is very contagious, plan to stay home for at least 48 hours after your symptoms have passed.

The 24-hour flu is often caused by one of two viruses: norovirus and rotavirus. Both viruses are shed in the stool of an infected person, meaning that you can become infected if you ingest tiny particles of stool from an infected person. This can occur when proper hygiene or food handling practices aren’t carried out. Symptoms typically occur one or two days after infection and can last for a few days. Viruses can’t be treated with medication. Since the infection is caused by a virus, treatment focuses on easing symptoms until you get better.

Although you can get the 24-hour flu from contaminated food and water, the condition is different from food poisoning. Food poisoning is caused by contamination of food or water, and can be caused by bacteria, viruses, or parasites. Often, the symptoms of food poisoning come on more quickly than the symptoms of 24-hour flu — usually within hours of ingesting contaminated food or water. Typically, the symptoms of food poisoning last a few days. Some types of food poisoning may last longer. Additionally, since various types of bacteria can cause food poisoning, antibiotics may be necessary to treat the infection.

If you’ve come down with the 24-hour flu, you can do the following things at home to help ease your symptoms:

• Drink plenty of fluids to replace the fluids lost from diarrhoea and vomiting. Examples include water, diluted juices, and broth. Electrolyte solutions, such as Pedialyte or diluted sports drinks (Gatorade, Powerade), can also be used.
• Eat plain or bland foods that are less likely to irritate your stomach. Examples include things like bread, rice, and crackers.
• Rest up. Getting plenty of rest can help your body fight the illness.
• Use an over-the-counter (OTC) anti-vomiting or anti-diarrheal medication. Be sure to talk to your doctor or pharmacist about which types may be appropriate for your condition.
• Take an OTC pain reliever such as acetaminophen (Tylenol) or ibuprofen (Advil, Motrin) to ease any body aches and pains.

Seek medical attention if you experience any of the following while you’re ill with the 24-hour flu:

• You have symptoms of severe dehydration, which can include dizziness, dark urine, or passing very low quantities of urine.
• You have bloody diarrhoea or vomit.
• You’re unable to keep any fluids down for 24 hours due to vomiting.
• Your fever is over 104°F (40°C).
• Your symptoms don’t begin to improve after a few days.
• You have an underlying condition such as inflammatory bowel disease or kidney disease.
• Your symptoms begin after you’ve travelled internationally, particularly to an area with poor sanitation.

The 24-hour flu is a highly contagious and short-lasting condition that’s caused by infection with a virus. The term “24-hour flu” is a bit of a misnomer, as the viruses that cause the condition aren’t related to the flu virus. Additionally, symptoms can last longer than 24 hours. If you come down with the 24-hour flu, you should be sure to stay home while you’re ill, and wash your hands frequently after using the bathroom and before handling food. Since dehydration can be a complication of 24-hour flu, you should also be sure to drink plenty of fluids to replenish those lost through diarrhoea and vomiting.

For children, new-borns, and infants, stomach flu can become dangerous. A person should call a doctor if a child has symptoms of a stomach flu.

There are some additional signs of dehydration to look for in young children, including:

• crying with few or no tears
• urinating less, or no wet diapers for 3 hours or more
• unusually sleepy or fussy
• Untreated dehydration can be fatal in children, so it is important to treat dehydration as an emergency.

Norovirus is the most common form of stomach flu. According to the Centres for Disease Control and Prevention (CDC)Trusted Source, every year in the U.S., it causes 19–21 million illnesses, around 109,000 hospitalizations, and 900 deaths of adults over 65 years of age. It is the most common cause of foodborne disease outbreaks in the U.S., causing 58% of cases.

A few simple measures can reduce the risk of catching stomach flu:

• Always wash hands before handling or preparing food and after using the toilet or changing a diaper.
• Wash all fruits and vegetables and thoroughly cook seafood before eating.
• Wipe shopping cart handles before use.
• Disinfect countertops and surfaces, and wash clothes and bedding.
• Use the dishwasher rather than washing dishes by hand.
• People who begin to feel ill should not prepare food for others.
• Sick family members should self-isolate, for instance, by restricting themselves to one bathroom.

For people who are not at high risk and have access to healthcare facilities, stomach flu often passes on its own without causing complications. Home remedies and general good hygiene can help prevent or ease symptoms. However, stomach flu can have strong, negative implications in some cases in people of all ages. A person should consult a doctor if they are experiencing severe symptoms or dehydration.