Stomach Flu – Symptoms, Risk Factors, Treatment and More

Stomach flu is also known as gastroenteritis and it’s a really unpleasant experience. Symptoms include diarrhea, nausea or vomiting, stomach cramps, and sometimes –  although not always – fever.  We generally develop stomach flu by coming into contact with somebody who already has it. It’s also transmitted by eating contaminated food or water.

Stomach flu symptoms

What are the most common stomach flu signs? Unlike ordinary flu, which gives us headaches, blocked noses, sore throats, and coughing, stomach flu attacks the intestines, leading to a watery but not usually bloody diarrhea, stomach pain and cramps, nausea, and sometimes vomiting and sometimes a low-level fever.

Some stomach flu patients also complain of muscular aches and headaches. However, it’s difficult to say if these are strictly the symptoms of stomach flu or whether they are just the result of the dehydration that accompanies having diarrhea and fever.

Stomach flu symptoms usually appear one to three days after infection. A mild case may last just a couple of days, although a severe bout of stomach flu can last for up to ten days. (1)

Is it stomach flu or something else?

It’s easy to confuse these stomach flu symptoms with other, similar, conditions such as food poisoning. In fact, doctors use the term gastroenteritis for a number of conditions including:


Also called the ‘winter vomiting disease’ and the ‘cruise ship bug’. This virus is transmitted in confined spaces and travels on contaminated food or in water. Salads are heavily incriminated in the transfer of Norovirus as it survives easily on food that is at room temperature.

It’s a nasty illness that most people shake off easily, but very young and older people can be badly affected. As many cruise ship passengers are seniors, this can be a serious condition for them. Oysters often cause stomach flu because they filter lots of water which can concentrate the norovirus in them.


An incredibly infectious stomach bug that is the biggest cause of diarrhea in babies and children worldwide. Most children recover quickly from stomach flu but around 20% will need to see a doctor.

A further 10% will end up hospitalized because of dehydration. Rotavirus is spread through feces: the reason it’s so common in children is they just don’t have good hygiene habits.

Adults may carry rotavirus without knowing it and pass it to children. In the USA there are two vaccines to prevent rotavirus. One is given at two months, four months, and six months of age. The other is given at two months and four months only.

Bacterial infection

Many infamous bacteria including Campylobacter, E. coli, Salmonella, and Shigella can cause gastroenteritis or stomach flu. Nearly half the bacterial stomach flu cases come from just one food – poultry. If food is infected with bacteria and remains at room temperature the bacteria multiply rapidly.

Poultry is a common meal around the world, and because it’s very moist, it’s the perfect breeding ground for many forms of bacteria. Other common bacteria-carrying foods are seafood and eggs, unpasteurized milk, and soft cheeses.

Parasitic stomach flu

This is now rare in the developed world, but parasites commonly cause gastroenteritis in other parts of the world, especially following a natural disaster. Giardia, Entamoeba, and Cryptosporidium are all parasites that cause violent stomach flu, particularly in children.

Stomach flu treatment

Sadly, there’s no effective treatment for stomach flu. This makes it vital to try and limit your exposure to the risk of developing it. Prevention is crucial:

  • Avoid potentially contaminated food – take extra care around food that’s been kept warm for long periods.
  • Don’t eat salad or cold food that could carry the stomach flu virus or bacteria.
  • Stay away from cold drinks that aren’t bottled.
  • Wash your hands frequently or use antibacterial hand gel to kill stomach flu bugs.
  • Don’t share towels, plates, or food with somebody who has stomach flu.

Because there’s no stomach flu medicine as such, we have to treat each symptom in turn. (2)

This illness is tough

Illness plus dehydration is exhausting. Bed rest is best when you have stomach flu. If you can’t manage that, make up your couch with pillows and blankets so you can doze there.

Stop eating solid foods to give your stomach a chance to calm down. But because you need to stay hydrated, sip water, or drink clear broth or miso soup. Soda isn’t recommended during stomach flu because carbonated drinks can irritate your gut.

You can try non-caffeinated sports drinks, but they give some people an even more upset stomach. Drink every hour you’re awake, taking small amounts of fluid at a time. When you start to feel better, introduce solid foods gradually.

Medication doesn’t always help stomach flu symptoms. NSAIDs can actually make your stomach pains worse. Tylenol can also harm your liver and so should be taken sparingly.

Aspirin sounds harmless, but for children, it can cause Reyes Syndrome – a rare condition that results from taking an aspirin when they already have a virus. A recent Australian study suggests we should always check out our medication when we develop stomach flu.

Children and stomach flu

Rehydration is crucial for children with stomach flu. (3)

Oral rehydration salts are available over the counter and are much better for your child than water. Don’t give apple juice as it can make diarrhea worse, as can dairy.

Reintroduce solid foods slowly, beginning with plain crackers or rice cakes, then dry toast. Rice, bananas, and potatoes can be added after a day or so. Babies and toddlers with stomach flu should have twenty minutes to recover after vomiting or a bowel movement.

Then offer them a small amount of liquid. Breast-feeding mothers can nurse normally, bottle-fed babies should have oral rehydration solution alternated with regular formula.

You should avoid using over-the-counter stomach flu remedies. While anti-diarrhea treatments can be useful in other illnesses, they can actually prevent a child’s body from eliminating the virus.

You probably won’t have to force your child to stay in bed. Illness and dehydration will exhaust them during a bout of stomach flu. Once they are on the mend, you may find you struggle to get them to rest. Try to keep children calm: pen and paper games, coloring books, and comics are ideal, computer games less so.

What to eat and what to avoid

Once you’re on the mend, reintroduce solid foods carefully. Begin with easily digestible items like plain crackers, dry toast, rice, and bananas. If you start to feel nauseous, stop eating, and return to a liquid diet for a couple of meals. It’s best to avoid dairy, caffeine, alcohol, and rich, highly seasoned foods until you’re back to full health. (4)

Should you call a doctor if you have stomach flu?

In adult stomach flu, calling a doctor often isn’t necessary. Antibiotics don’t work against viruses, so if you have viral gastroenteritis you don’t need them. Getting a stomach flu diagnosis often involves taking a stool sample.

But always call a doctor if you:

  • Vomit for more than 48 hours, or vomit blood
  • Have blood in your bowel movements
  • Can’t keep liquids down for over 24 hours
  • Have a fever over 104 F.

Children, stomach flu, and medical attention

When a child has stomach flu, contact your doctor or pediatrician if they develop a fever over 102 F. Other symptoms that require medical supervision are bloody diarrhea, extreme lethargy, and unresponsiveness. A child with extreme dehydration may require hospitalization, but this is rare.

Babies should always have medical supervision when ill. Signs of severe stomach flu in babies include:

  • Vomiting that lasts more than four hours
  • Not having a wet diaper in the previous six hours
  • Bloody stools or more than three bouts of diarrhea in a row
  • A dry or cracked mouth or crying without producing tears
  • Extreme lethargy, unusual sleepiness, or unresponsiveness.

Risk factors

Young children and older adults are prone to stomach flu. Children have undeveloped immune systems while seniors often have weakened ones. Children and older people also spend time in community settings like schools and care homes where stomach flu transmits easily.

Check out the routines in such settings, looking for regular cleaning of common areas and the use of disposable gloves and hand sanitizer.

Cruise ships, residential weekends, and dormitories are all risk factors so wash your hands regularly in such places. Drink only bottled water and avoid salads and any fruits that haven’t been cooked.

Chemotherapy, HIV/AIDS, and other compromised immune conditions put you at high risk – ensuring good hygiene is vital for protection.

Stomach flu has seasonal peaks – in the northern hemisphere, this is October to April.

Stomach flu remedies

Ginger helps a lot of people with stomach flu. Grate the ginger root into hot water to make a soothing tea. Peppermint can also be valuable – make it into a hot tea to soothe your stomach lining. Other teas that are famous for helping stomach cramps are rooibos and chamomile. Fennel tea, or braised fennel root, is a tasty way to reduce indigestion and cramping.

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