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Gastroenteritis

Expert reviewer, Dr Joanne Byfleet, Bupa Clinics GP
Next review due August 2023

Gastroenteritis is a common condition that triggers diarrhoea, sickness and tummy pain. It’s usually caused by an infection and most people get better after a few days.

A family eating breakfast

About gastroenteritis

Gastroenteritis makes the lining of your tummy or bowel sore and swollen (inflamed) so it doesn’t work properly. It’s usually caused by either a viral or bacterial infection. Some people refer to it as a tummy bug, food poisoning and traveller’s diarrhoea.

In the UK, around one in five people gets gastroenteritis each year. You can get gastroenteritis if you eat or drink anything containing bacteria, viruses or parasites. You can also catch it from someone who has the infection, or by touching objects and surfaces that they’ve touched before you.

If you have gastroenteritis, you may have a mild tummy upset that you can treat at home. But some people, including those with underlying health conditions, babies and older people, can develop very bad diarrhoea and sickness. This can lead to dehydration, which may need medical treatment.

Symptoms of gastroenteritis

It can take up to three days for your symptoms to appear after you’ve caught the infection. Your symptoms may include:

  • diarrhoea (very loose and watery poo, sometimes containing blood or mucus)
  • feeling sick or being sick
  • tummy pain
  • rumbling noises from your tummy

You may also:

  • have a temperature (fever)
  • feel generally unwell
  • not feel hungry
  • have aching muscles
  • have headaches

In adults, gastroenteritis symptoms can last for up to a week. But call your GP surgery if they’re not getting any better (or get worse) after two days. You should always seek medical advice if you notice blood in your poo in case there’s a more serious underlying cause, such as bowel cancer.

If your symptoms last for a long time, there may be another cause, such as irritable bowel syndrome or inflammatory bowel disease, such as Crohn’s disease. Diarrhoea and vomiting may also be side-effects of medicines you’re taking. Always seek medical advice if you’re taking any medicines, as your GP may suggest an alternative.

If your child has diarrhoea, this usually lasts for up to a week or, occasionally, two weeks. If they’re being sick, this usually lasts for two to three days. If your child’s symptoms are very bad or not getting any better, or if they seem generally unwell, call your GP surgery for advice.

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Diagnosis of gastroenteritis

Most people with gastroenteritis don’t need to see a GP, as their symptoms get better on their own. But if you’re worried about your symptoms, call your doctor’s surgery. It’s not recommended to see your GP in person unless you’re asked to. This is because you may spread it to other people. You may have a telephone consultation instead.

Your GP may ask:

  • how often you’ve been sick
  • how often you’re pooing and what your poo looks like
  • whether you’ve noticed any blood in your poo
  • whether you’ve been able to eat or drink without being sick – and how much you’re drinking
  • whether you’ve been in contact with someone who’s had similar symptoms
  • whether you’ve been abroad recently
  • your medical history, including if you’re taking any medicines

Your GP may check your temperature, blood pressure, heart rate and how quickly you’re breathing. They’ll check whether your tummy feels sore and look for signs of dehydration. See our FAQ on How can I tell if my child is dehydrated?

Occasionally, your GP will send a sample of your poo to a laboratory for testing. This may be because you’ve had symptoms for a while, you’re very unwell or there’s blood in your poo. They may also send a sample for testing if you’ve travelled abroad recently.

Treatment of gastroenteritis

Most people with gastroenteritis get better at home after a few days and don’t need any specific treatment. But, sometimes, if your symptoms are very bad or you’re dehydrated, you may need some medical help.

Self-help for gastroenteritis

If you have gastroenteritis, you can pass the infection on to other people. So stay at home and don’t go into work for at least 48 hours after your diarrhoea and sickness have stopped. If your child has the infection, they should stay off nursery or school for this length of time too.

If you take medicines regularly, you should keep taking them as usual if you have diarrhoea or sickness. But check the patient information leaflet that comes with your medicines. Gastroenteritis can affect how well some medicines work, especially the contraceptive pill. If you need any advice, speak to a pharmacist.

How quickly you get better will depend on which infection you have. Some viral gastroenteritis infections last only a day or two, but other infections can last for a week or even longer.

What to eat and drink

If you have diarrhoea and sickness your body will be losing more fluid than usual. You need to make sure you replace this by keeping hydrated, drinking plenty of fluids, such as water or squash.

If your baby has gastroenteritis, keep breastfeeding them or give their other milk feeds. It’s best not to give young children fruit juices or fizzy drinks while they still have symptoms.

When you feel hungry again, eat small, light meals, but don't have anything fatty or spicy. Some research shows that eating cereals, banana, rice and toast at first may help.

Probiotics

Probiotics are supplements or foods (such as live yoghurt) that contain ‘good’ bacteria. They may help to reduce how long you have diarrhoea. See our FAQ on Can probiotics help gastroenteritis.

Oral rehydration solutions

Oral rehydration solutions come as a powder that you add to water to make a drink. Oral rehydration solutions have the right mix of sugars, minerals and salts to help you replace lost water and salt. Most people with gastroenteritis get better without needing one of these solutions. But these products may be helpful for:

  • older people
  • people who have other illnesses
  • young children

Ask a pharmacist if an oral rehydration solution might be suitable for you.

Sports drinks don’t have the right mix of sugar, minerals and salts, so it’s best not to use them for rehydration, especially in young children.

Medicines

If you have gastroenteritis, you don’t usually need medicines that stop diarrhoea, such as loperamide (eg Imodium). But you may find these medicines useful if you need to stop your diarrhoea quickly (such as when travelling) or can’t get to a toilet easily.

You can buy loperamide from pharmacies, but this should only be taken by adults and children over 12 years, unless prescribed by a doctor. Don’t take these medicines if you have blood or mucus in your poo or a fever, as they could make you feel worse.

If you can’t stop being sick, or feel very sick, a doctor may prescribe an anti-sickness (antiemetic) medicine. Your GP won’t usually prescribe antibiotics for gastroenteritis as these won’t help your symptoms. If they think you may have a bacterial infection, they’ll probably ask you to provide a poo sample. If this shows you have bacterial gastroenteritis, they may then prescribe antibiotics.

Hospital treatment

If you become very dehydrated or unwell, you may need to be admitted to hospital. In hospital, you can be given fluids directly into your bloodstream through a fine tube into your vein.

Causes of gastroenteritis

Gastroenteritis has lots of different causes. It may be an infection due to:

  • viruses, such as rotavirus, norovirus or adenovirus – especially in children
  • bacteria in contaminated food or drink – such as Salmonella, Campylobacter and Escherichia coli (E. coli)
  • parasites, such as Cryptosporidium, Entamoeba and Giardia

You may pick up an infection:

  • by eating raw, undercooked or contaminated food, such as meat, shellfish or unpasteurised milk
  • from someone else with gastroenteritis – they may not have washed their hands properly after going to the loo
  • by drinking contaminated water
  • touching an infected animal

Occasionally, gastroenteritis can be triggered by:

  • some medicines, such as antibiotics, which upset the natural balance of bacteria in your gut
  • eating toxins, which may be made by certain bacteria and fish

Complications of gastroenteritis

If diarrhoea or sickness is very bad, this can cause dehydration, especially in children. This happens when you’re losing lots of fluid and you don’t drink enough fluid to make up for it. Sickness and diarrhoea can also make the salts and minerals in your body get out of balance. Being very dehydrated can be dangerous. See our FAQ on How can I tell if my child is dehydrated?

Gastroenteritis can also cause:

  • lactose intolerance, which makes you sensitive to dairy products, usually for a short while
  • reactive arthritis or other conditions where your body’s immune system mistakenly attacks your own tissues – this only usually happens after bacterial gastroenteritis
  • haemolytic uraemic syndrome, which is a serious kidney problem
  • irritable bowel syndrome (IBS)

Complications mainly affect:

  • young children
  • older people (the over-60s)
  • people with other health problems
  • people with a weak immune system
  • people taking certain medicines, such as corticosteroids

When to seek medical help for gastroenteritis

Most people with gastroenteritis get better at home without seeing a doctor. But contact your GP if you:

  • are being sick a lot and can’t keep down any fluids
  • have blood in your diarrhoea
  • have a high temperature (fever)
  • have had diarrhoea for more than 10 days
  • can’t control your bowels
  • have signs of dehydration, such as a dry mouth, muscle cramps, peeing very little, sunken eyes, confusion or irritability
  • have recently been abroad
  • have kidney or liver disease
  • have other long-term conditions, such as a weak immune system, diabetes or inflammatory bowel disease
  • don’t have someone who can look after you at home and your symptoms are very bad

It’s important to seek medical help if you think a child with gastroenteritis is dehydrated. See our FAQ on How can I tell if my child is dehydrated?

Preventing spread of gastroenteritis

To stop you getting or spreading gastroenteritis, follow these tips.

  • Always wash your hands with soap and water after going to the loo or changing your baby’s nappy.
  • Practise good food hygiene , and always wash your hands before and after preparing or eating food.
  • Wash dirty clothing or bed linen separately and at the highest temperature possible (60°C or higher if possible). Only half fill the washing machine, so everything is very clean and well-rinsed.
  • Clean loo seats, flush handles, taps, surfaces and door handles every day with soap and hot water. If you have a disinfectant, use this to clean the loo. Throw away any cleaning cloths after you’ve used them – or use them just for cleaning the loo and nothing else.
  • Don't share towels or flannels.
  • Don’t go swimming for at least two weeks after your diarrhoea has stopped if you’ve been diagnosed with a parasite called Cryptosporidium.
  • Stay off work for at least 48 hours after your diarrhoea or sickness has stopped. Stay away from hospitals and GP surgeries if you can too. This will stop you spreading the infection to people who are most likely to get complications.

Young babies can be immunised against rotavirus, a common cause of gastroenteritis. This is given as drops into their mouth in two doses – the first at two months and the second at three months.

Before travelling to another country, check which precautions you should take at www.travelhealthpro.org.uk. You may need vaccinations or to drink bottled water, for example.

Frequently asked questions about gastroenteritis

  • If you have gastroenteritis, you probably won’t feel like eating. But it’s important to keep your fluids up. If you have diarrhoea and sickness your body will be losing more fluid than usual. Make sure you replace this by keeping hydrated, drinking plenty of fluids, such as water or squash.

    When you feel hungry again, eat small, light meals, but don't have anything fatty or spicy. Some research shows that eating cereals, banana, rice and toast at first may help.

  • Infections can be picked up from contaminated food and water on holiday. So, when you’re abroad, be careful by:

    • eating at restaurants with a good hygiene reputation
    • being careful about eating food from street vendors and buffets
    • choosing food that’s served very hot
    • avoiding raw vegetables or food that’s been left out
    • only eating fruit that you’ve peeled yourself
    • avoiding ice (unless you know it’s made from clean water)
    • drinking water and other drinks from bottles only (with an intact seal); boiling or chemically purifying water after using a reliable filter

    Always pack some medicines just in case you get ill. You may wish to pack oral hydration solutions or medicines to treat diarrhoea. Ask a pharmacist for advice before you travel.

    Also make sure you get any travel vaccinations that you need. Book an appointment at your GP surgery or a travel clinic before you go – ideally, four to six weeks beforehand.

  • Gastroenteritis can make babies and children get dehydrated very quickly, which can be dangerous. Your child may be getting dehydrated if they:

    • seem irritable and tired
    • are peeing less
    • have less-elastic skin than usual – when gently pinched, their skin doesn't spring back into position straightaway
    • have a dry mouth
    • have sunken eyes
    • have a quicker than usual heart rate
    • are breathing quickly

    If you think your child may be dehydrated, call your GP surgery for advice straightaway.

  • Gastroenteritis is usually caused by harmful bacteria, viruses or parasites that get into your gut. Probiotics are ‘good’ bacteria, such as Lactobacilli, that are found in certain foods (such as live yoghurts) and food supplements. They may help to correct the balance of bacteria and other organisms in your gut, helping to keep you healthy.

    Some research shows that probiotics may help to ease diarrhoea so you get better more quickly. They may also help to prevent some types of gastroenteritis, such as traveller’s diarrhoea. But more research is needed before doctors can be sure, because not all studies have found that probiotics made a difference. Doctors think it’s generally safe to take probiotics. But if you have a weak immune system, speak to a dietitian or GP first.



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Related information


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    • Personal communication. Dr Joanne Byfleet, GP and Lead Physician at Bupa, August 2020
  • Reviewed by Victoria Goldman, Freelance Health Editor, and Alice Windsor, Specialist Health Editor, Bupa Health Content Team, August 2020
    Expert reviewer, Dr Joanne Byfleet, Bupa Clinics GP
    Next review due August 2023

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