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Key points

  • Gastroenteritis is an infection of your stomach or bowels, that may be caused by viruses, bacteria, or parasites. 
  • Most cases of gastroenteritis are caused by norovirus (viral ‘winter vomiting’ bug) or bacterial food poisoning.
  • Most people with gastroenteritis get better at home after a few days. But sometimes the condition may last for longer.
  • If you’re infected, stay home for 48 hours after your symptoms stop, as gastroenteritis can spread easily.

What is gastroenteritis?

Gastroenteritis is very common condition that causes diarrhoea, sickness, and tummy pain. It's also called a tummy bug, stomach flu or gastric flu. It's usually mild and clears up on its own in a few days. But for babies, older adults, and those with certain health conditions or weakened immune systems, it can be more serious.

Symptoms of gastroenteritis

Symptoms come on suddenly. Stomach bug symptoms may include:

  • diarrhoea (loose and watery poo)
  • feeling or being sick
  • tummy pain or cramps

You may also:

  • have a temperature (fever)
  • feel generally unwell
  • lose your appetite
  • have aching muscles
  • have headaches

For viral infections, you’ll usually get symptoms about a day after catching the virus. For infection with bacteria or parasites, symptoms usually appear later. Gastroenteritis symptoms can last for up to a week, or sometimes more.

When to get medical help for gastroenteritis

Sometimes gastroenteritis can become more serious, and you may need medical help. Contact a GP if you:

  • have signs of severe dehydration, such as passing little or no urine
  • feel weak, dizzy, or confused, have headaches and muscle cramps due to dehydration
  • are constantly being sick and can’t keep down any fluids
  • have severe or uncontrollable diarrhoea that’s making you dehydrated
  • have diarrhoea with blood or pus in it
  • have recently been abroad
  • have other illnesses or long-term conditions or a weak immune system
  • are too unwell to care for yourself properly at home
  • aren’t starting to feel better within a week or are still having diarrhoea

Babies under one year are at particular risk of developing dehydration. Signs of dehydration in children and babies include peeing less, seeming irritable, and having a dry mouth and sunken eyes.

Seek medical help if you think a child with gastroenteritis is dehydrated.

Under 18 GP Appointments

We now offer GP appointments for children aged children under 18 via our remote video service (UK wide) and face to face appointments at selected centres. Please note that these appointments cannot be booked online so please call 0330 822 3072 for more information or to book. Lines are open Monday to Friday 8am to 8pm, Saturday and Sunday 9am to 5pm. We may record and monitor our calls. Available from £49.

To book or to make an enquiry, call us on 0343 253 8381

Self-help for gastroenteritis

Most people with gastroenteritis get better at home after a few days.

  • Stay at home and rest until you feel better.
  • You shouldn’t go into work or mix with others for at least 48 hours after your diarrhoea and sickness have stopped. This stops you spreading the infection.
  • If your child has the infection, they should stay home from nursery or school. They should stay home for at least 48 hours after their symptoms stop.

Self-help treatments for gastroenteritis include:

  • drink plenty of fluids to keep hydrated
  • use oral rehydration drinks, available from a pharmacy, supermarket or online

What can you eat when you have gastroenteritis?

Eat when you feel able to. Start with bland foods like toast, crackers, rice, and lean meats. Avoid fatty or spicy foods at first. Gradually return to your normal diet when you can and make sure you are drinking enough fluids. This is especially important for children.

Causes of gastroenteritis

Gastroenteritis may be caused by viruses, bacteria, or parasites, including:

  • stomach viruses like norovirus, rotavirus, and adenovirus. The winter vomiting bug (norovirus) is the most common type of viral gastroenteritis
  • bacteria such as Campylobacter, Salmonella, and E. coli, that usually cause food poisoning. You get them from undercooked meat, unpasteurised milk, and contaminated water
  • parasites like Cryptosporidium, Entamoeba, and Giardia. You can get them from infected animals, contaminated water, or food
  • travellers' diarrhoea, which is a type of gastroenteritis you can get while travelling

How do you catch gastroenteritis?

There are lots of ways to catch gastroenteritis. Viral gastroenteritis is contagious. You can catch it from someone who’s infected if you encounter particles of their poo or vomit.

You can also catch it from food or drinking water contaminated with viruses, bacteria, or parasites.

Complications of gastroenteritis

Gastroenteritis is usually a mild illness that you recover from quickly. But it can lead to more serious complications in:

  • young children
  • older adults
  • people with a weak immune system – from either a health condition, such as HIV/AIDS, chemotherapy or medication

Complications can also depend on exactly what’s caused your infection.

Can gastroenteritis cause dehydration?

If diarrhoea or sickness is very bad, this can cause dehydration. Babies younger than one year are particularly at risk. If you’re severely dehydrated, you may:

  • pass little or no urine
  • feel weak, dizzy or confused
  • have headaches
  • have muscle cramps

Being very dehydrated can be dangerous and it’s important to get the right treatment.

Are there other complications of gastroenteritis?

Other complications of gastroenteritis may include the following.

  • Lactose intolerance. This can make you sensitive to dairy products. It’s usually temporary.
  • Irritable bowel syndrome (IBS). This can cause ongoing symptoms, like diarrhoea, constipation, and bloating.
  • Reactive arthritis. This is a type of arthritis that usually only lasts for a short time. It causes swelling in your joints and sore eyes.
  • Haemolytic uraemic syndrome. This is a serious kidney problem, often causing bloody diarrhoea. It’s more common in young children.
  • Toxic megacolon. This is a serious complication in which part of your bowel becomes inflamed. It can be life-threatening if you don’t get treatment quickly.

Preventing spread of gastroenteritis

If you or someone in your household has gastroenteritis, take the following measures to reduce the risk of spreading it.

  • Wash your hands with soap and warm, running water after going to the toilet. If you have a baby with gastroenteritis, wash your hands after changing their nappy.
  • Wash your hands before and after preparing, serving or eating food.
  • Wash dirty clothing or bed linen separately and at the highest temperature possible. The washing machine shouldn’t be more than half full, to make sure everything is properly cleaned and well-rinsed.
  • Clean toilet seats, flush handles, taps, surfaces and toilet door handles every day with detergent and hot water. Use disinfectant and a disposable cloth to clean the toilet.
  • Don't share towels or flannels.
  • If you’ve been diagnosed with the parasites Cryptosporidium or Giardia, there are rules about swimming. Don’t go swimming for at least two weeks after your diarrhoea has stopped.
  • Stay off work or school for at least 48 hours after your diarrhoea or sickness has stopped. If you can, stay away from hospitals and GP surgeries too. This will stop spreading the infection to people who are most likely to get complications.

Watch our video on how to wash your hands effectively in 20 seconds. This prevents germs, including viruses, from spreading.

Parents and carers might also find it helpful to watch Bupa’s short animation about germs. They can watch it with their child. The animation is for primary school-aged children, to help them understand the importance of hygiene.

GP Subscriptions

You can’t predict when you might want to see a GP, but you can be ready for when you do. Our GP subscriptions are available to anyone over 18 and give you peace of mind, with 15-minute appointments when it suits you at no extra cost.

More on this topic

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