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Gastroenteritis

This information was published by Bupa's Health Content Team and has been reviewed by appropriate medical or clinical professionals. To the best of their knowledge the information is current and based on reputable sources of medical evidence, however Bupa (Asia) Limited makes no representation or warranty as to the completeness or accuracy of the Content.

The information on this page, and any information on third party websites referred to on this page, is provided as a guide only.  It should not be relied upon as a substitute for professional medical advice, nor is it intended to be used for medical diagnosis or treatment. Bupa (Asia) Limited is not liable for any loss or damage you suffer arising out of the use of, or reliance on, the information.

Third party websites are not owned or controlled by Bupa and any individual may be able to access and post messages on them. Bupa is not responsible for the content or availability of these third party websites. 

Gastroenteritis is an inflammation of the stomach and intestines caused by infection. In most cases, gastroenteritis clears up without the need for specific medical treatment.

The stomach and intestines are known collectively as the gastrointestinal tract - or gut. Gastroenteritis is an infection of the gut. You can get infected from eating or drinking food that is contaminated with bacteria, viruses or parasites, or from other infected people (for more information, see Causes).

Some of these germs can damage the cells lining the inner surface of the gut and interfere with its normal functions.
Certain bacteria or viruses may also produce toxins that irritate the gut and cause it to produce excess amounts of fluid. This can lead to the various symptoms of gastroenteritis such as diarrhoea.

You can get gastroenteritis from eating or drinking food that is contaminated with bacteria, viruses or parasites. You can also catch gastroenteritis from another person with it.

The infections that cause gastroenteritis can damage the cells lining the inner surface of the gut and interfere with its normal functions. Certain bacteria or viruses may also produce toxins that irritate the gut and cause it to produce excess amounts of fluid. This can lead to various symptoms of gastroenteritis, such as diarrheoa.

 

The time between catching the infection and the start of your symptoms (the incubation period) depends on the type of infection you have. It’s usually between one and three days, but symptoms can sometimes come on faster or slower than this.

Symptoms include:

  • Diarrhoea, which may contain blood or mucus, be watery, greasy or frothy
  • Feeling sick of vomiting
  • Abdominal cramps or pain, bloating, stomach rumbling
  • Loss of appetite
  • Headaches
  • Fever

These symptoms can sometimes be caused by other problems, such as other types of infections, irritable bowel syndrome, ulcerative colitis or side-effect of medicines. However, these problems will usually cause symptoms that last for a lot longer than gastroenteritis.

The time it takes to recover depends on which infection you have. Some viral infections only last a day or two, while other infections can take a week or more to recover from. Some infections can even last for several weeks, but these are uncommon in Hong Kong.

For children with gastroenteritis, diarrhoea usually lasts for five to seven days and stops within two weeks. Vomiting usually lasts for one or two days, stopping within three days. If your child’s symptoms continue for longer than this, seek medical advice.

If your symptoms persist, contact your GP. They may ask:

  • About your medical history
  • How often you’ve vomited
  • How often you’ve had a bowel movement and its consistency
  • Whether you have any blood in your faeces
  • How often you’re passing urine
  • About any abdominal pain
  • Whether you’ve been able to keep down any food or drink
  • Whether you’ve had contact with someone who has had similar symptoms
  • Whether you’ve been abroad recently (especially which countries you have visited)
  • For a faeces (stool) sample for laboratory testing

The main cause of gastroenteritis is an infection with a virus, bacteria or parasite. Les commonly, you can get gastroenteritis as a side-effect of some medication or from eating toxins.

You can pick up an infection in different ways. These include:

  • Eating raw, undercooked or contaminated food, such as meat, shellfish or unpasteurized milk
  • From another person – either by inhaling infected particles in the air or touching infected surfaces
  • Touching an infected animal

 

Viruses

 

Viruses are a common cause of gastroenteritis, particularly in children. These include:

  • Rotavirus – the most common cause of gastroenteritis in babies
  • Norovirus – this is very contagious, but the infection usually passes in a couple of days
  • Adenovirus – this is another common cause of gastroenteritis in young children
  • Hepatitis A

Viral infections can be seasonal, meaning they happen more often at certain times of year. For example, more people get norovirus infections during the winter and spring.

Bacteria

 

The most common cause of bacterial gastroenteritis is food poisoning. Food poisoning is cause by different bacteria, from different foods. For instance:

  • Salmonella – dairy, eggs and poultry
  • Campylobacter- dairy, meats and poultry
  • Bacillus – reheated rice
  • Vibrio – seafood
  • Escherichia coli (E. coli) – minced beef

Some E. coli strains are particularly harmful, including E. coli 0157, which produces a toxin that can also damage the kidneys, cause red blood cells to break down and cause inflammation in small blood vessels. These infections can be fatal and children can be particularly vulnerable.

Parasites

 

Parasites rarely cause gastroenteritis in Hong Kong. You might pick them up when travelling abroad or from animals.

 

The infections are transmitted:

  • In contaminated food
  • From person to person
  • If an individual infected with a virus sneezes or coughs, as another person could inhale the virus
  • In shellfish harvested in polluted waters
  • In contaminated drinking water

Try to manage your symptoms at home because gastroenteritis is often very contagious. It’s best to keep away from doctors’ surgeries and hospitals so you don’t spread it to people who are at high risk of complications.

Self-help

What to eat and drink

If you have a mild gastroenteritis, drinks such as water or squash will help you stay hydrated. Sport drinks can also be good as they contain glucose and often some electrolytes. Avoid fizzy drinks at all costs, as they will not help to keep you hydrated.

Once you’re hydrated, have small, light meals when you feel hungry, but avoid fatty or spicy foods. Fruit juices or soup may help you to replace lost salts, but it’s best not to give young children fruit juices while they’re unwell.

Oral rehydration solutions 

If you have a more severe infection, use an oral re-hydration solution (eg Dioralyte), which you can buy in pharmacies. They can help your body to replace lost water. They can be particularly helpful:

  • For people over 60
  • People who have frail or have other illnesses
  • Children

 Oral rehydration solutions come as a power that you add to water to make a drink. They have the right mix of sugars and electrolytes (minerals and salts) to help you replace lost water and salt. You should also eat foods high in carbohydrates such as rice or toast until you can take solid food and return to your normal diet.

Probiotics

Certain probiotics (supplements or foods containing ‘good’ bacteria) may help to reduce the time you have diarrhoea for.

Medicines

Medicines to stop diarrhoea such as loperamide (eg Imodium) are only recommended for people over four. These medications slow down movement in the intestines, preventing diarrhoea temporarily. They can be useful in some situations, for example, if you need to travel. They can also cause side-effects such as tummy cramps, dizziness and skin reactions.

If you are in pain, take the painkiller that you would normally take for a headache. Follow the instructions in the patient information leaflet that comes with the medicine and ask your pharmacist for advice.

If you have severe vomiting, your GP may prescribe an anti-sickness medicine (anti-emetic). Many anti-emetics are also sedatives, so it is advisable not to drive or use machinery after taking them.

Your GP won’t usually prescribe antibiotics unless a sample of your faeces that has been tested shows that antibiotics would help. This is because antibiotics don’t help to treat some types of gastroenteritis (those caused by viruses, for example).

Hospital treatment

If you have become very dehydrated, you may need to be admitted to a hospital. At the hospital, fluid can be put directly into your bloodstream via a catheter put into your vein (intravenously) to rehydrate you.

Complications from gastroenteritis occur mainly in the young and the old, people with chronic gastroenteritis and in those who have weakened immune systems.

Possible complications of gastroenteritis include:

  • Dehydration and incorrect levels of electrolytes (minerals and salts)
  • Lactose intolerance, which causes sensitivity to dairy products
  • Malnutrition (not eating sufficient food, or the right balance of food)
  • Haemolytic uraemic syndrome, which can cause serious kidney problems
  • Irritable bowel syndrome

 

 If you become very unwell, you may need to be admitted to a hospital. Contact your GP if you:

  • Have had vomiting or diarrhoea for more than a few days, and you can’t keep do wn any fluids
  • Have blood in your dirrhoea
  • Have a fever
  • Have had dirrhoea for more than 10 days
  • Can’t control your bowels
  • Have signs of dehydration, such as a dry mouth, muscle cramps, passing little urine, sunken eyes, confusion or irritability
  • Have recently travelled abroad
  • Have other long-term conditions such as human immunodeficiency virus (HIV), diabetes or IBS
  • Don’t have someone who can look after you at home and your symptoms are severe or you’re elderly

To reduce your chance of getting gastroenteritis, follow these tips:

  • Always wash your hands with soap and water after going to the toilet or changing your baby’s nappy.
  • Always wash your hands before and after preparing or eating food.
  • Wash soiled clothing or bed linen separately from other laundry and at the highest temperature possible (60 or higher if possible). Only half fill the washing machine, so that everything is thoroughly cleaned and rinsed.
  • Clean toilet seats, flush handles, taps, surfaces and door handles daily with hot water and disinfectant. Use a cloth that can be thrown away or one that is only used for this purpose.
  • Don’t share towels and flannels.
  • Don’t go swimming for at least two weeks after your diarrhoea has stopped.

If you have gastroenteritis, you may well have an infection that you could pass on to others. Stay at home and don’t go into work for at least 48 hours or until you’re better. Make sure you wash your hands regularly and disinfect surfaces and door handles.

If your child has gastroenteritis, keep them off school until they’re better. Stay away from hospitals and doctors’ surgeries if possible so you don’t spread it to people who are at high risk of complications. If you’re feeling very unwell and think you need to see a GP, contact him by phone and he will advise you on what’s best to do.

1. What are probiotics and how can they help if I have gastroenteritis?

Probiotics are a food supplement. They contain live bacteria and yeasts that can be helpful in restoring the balance of bacteria in your gut after a bout of gastroenteritis.

Probiotics are food supplements containing live bacteria and yeasts that help restore the balance of bacteria in your gut. Bacteria are often thought of as harmful and causing ill-health, but there are many good bacteria that live in and on your body that help keep you healthy. This is especially so in your gut. Good bacteria in your gastrointestinal tract prevent harmful organisms from growing in your bowel or entering your body through your intestine.

Gastroenteritis is an infection in your gut caused by harmful bacteria, viruses or parasites. These germs damage the cells lining the inner surface of your gut interfering with its normal processes and upsetting the balance of bacteria. Taking probiotics which contain bacteria such as lactobacillus helps to restore the balance of good bacteria in your gut. This can relieve symptoms of diarrhoea and speed up your recovery.

You can buy probiotics as food supplements (capsules or tablets) from your pharmacist or health food shop. Always read the patient information leaflet that comes with your supplements. Or, they can be bought as yogurts or drinks (eg Danone Activa or Actimel) from your supermarket. Plain yogurts don't contain probiotics.

If you have any questions or concerns about probiotics or gastroenteritis, talk to your GP.

2. Why are people who take antibiotics more prone to getting gastroenteritis?

Some antibiotics can upset the balance of good bacteria in your gut allowing harmful bacteria to thrive. This is often referred to as antibiotic-associated diarrhoea and can cause painful stomach cramps and watery diarrhoea.

Antibiotics are medicines prescribed by doctors to treat infections (for example, a kidney infection). They are used to kill or prevent the growth of harmful bacteria in your body. However, some antibiotics, such as ampicillin, clindamycin, and cephalosporins, will also kill the normal bacteria in your gut. This can allow other bacteria such as Clostridium difficile (C. difficile), to grow and thrive in your gastrointestinal tract. As this bacterium multiplies and divides, it produces a toxin which causes pain in your abdomen and watery diarrhoea - gastroenteritis. This is also known as antibiotic-associated diarrhoea.

It's not clear how many people get diarrhoea as a result of taking antibiotics. It has been estimated that it could be as many as one in four people, although the actual number may be much lower.

Most people who get antibiotic-associated diarrhoea experience only mild symptoms that usually resolve themselves quite quickly. It's important to seek advice from your GP if you have symptoms rather than stopping the course of antibiotics yourself. If possible, he or she will take you off the antibiotic and prescribe a different type.

While you have symptoms, you should continue with your normal diet, but leave out fatty foods or food and drink with a high sugar content, and make sure you drink enough fluids. You may find that you become intolerant to milk for a couple of weeks after your bout of gastroenteritis. This is because you are temporarily unable to break down the lactose (milk sugar) in it, giving you diarrhoea. Milk and milk products are best avoided if they make your diarrhoea worse. If you have become dehydrated, you can take oral rehydration salts (eg Dioralyte). Taking probiotic supplements or yogurt drinks can also be helpful in easing symptoms of diarrohea.

Very occasionally, a C. difficile infection in your gut can develop into a serious disease and symptoms can be severe. If your diarrhoea doesn't improve and you are in a lot of discomfort, you should see your GP as soon as you can. He or she will take a stool sample and blood test for analysis before referring you on for further treatment.

If you have any questions or concerns about antibiotics or gastroenteritis, talk to your GP.

3. How should I prepare food to avoid getting gastroenteritis or giving it to others?

Every year millions of people suffer from gastroenteritis caused by poorly prepared or stored food. Following food hygiene measures can ensure that you and the people you cook for don't become ill.

To prevent gastroenteritis it's important to take care over how you prepare, cook and store food. The following food hygiene tips will help you to keep yourself and those you cook for safe.

Preparing food

When preparing food it's important to make sure that bacteria aren't spread through cross-contamination, for example, raw food placed in contact with food that is ready to eat, cooking utensils, chopping boards or people's hands. To prevent this:

  • wash your hands before you start preparing food and after touching raw food (especially meat)
  • prepare raw foods and foods that are ready to eat separately
  • clean knives and chopping boards thoroughly after you have used them to prepare raw meat
  • keep cloths, tea towels and hand towels clean and change them regularly

Cooking food

During cooking any harmful bacteria in your food are destroyed, so it's important to make sure you cook everything properly. Do this by:

  • allowing meat and poultry to thaw thoroughly before cooking
  • making sure your food is hot all the way through before you eat it
  • never reheating food more than once

Storing food

Some foods need to be kept chilled in the fridge to keep them safe. When storing these types of food always:

  • put them in the fridge straight away
  • cool cooked foods as quickly as possible before putting them in the fridge
  • use separate, sealed containers to store raw meat and poultry in your fridge
  • don't overfill your fridge, otherwise the cold air won't be able to flow properly and food may become too warm

When preparing food for the elderly, babies and toddlers, pregnant women or people who are ill, don't give them food that contains any raw or runny eggs (ie mayonnaise). Raw eggs can contain bacteria which may be harmful to those people.

Food hygiene standards are not always as high abroad as they are at home. Also, you may encounter bacteria that you have not been exposed to before. To reduce the risks while on holiday try to do the following.

  • Ensure you have any suggested vaccinations well before leaving, in particular typhoid and cholera. Your GP will have an up-to-date list of these for the area you are visiting.
  • Only drink bottled water and ensure the seal has not been broken when you buy it. You should also use this for brushing your teeth. Avoid ice in drinks if you don't know where the water came from.
  • Peel fruit and avoid salad leaves unless you have washed them yourself in bottled or sterilised water.
  • Be cautious with shellfish and eggs (especially raw eggs in foods like mayonnaise) which are the commonest source of salmonella abroad.
  • If you have any questions or concerns about gastroenteritis and food hygiene, talk to your GP.

4. How can I tell if my child's gastroenteritis is making them dehydrated?

Gastroenteritis can cause babies and children to become dehydrated quickly, which can be dangerous. Signs of dehydration include a dry mouth, passing little urine, being lethargic and irritable, and loss of skin elasticity. If your child has these symptoms, seek medical advice.

In babies and young children, gastroenteritis can be more dangerous because they become dehydrated more easily.

Symptoms of dehydration include:

  • being irritable and tired
  • urinating less
  • loss of skin elasticity – when gently pinched, the skin doesn't immediately spring back into position
  • dry mouth
  • sunken eyes
  • fast heart rate
  • rapid, shallow breathing
  • blood taking longer to return to hands or feet when gently squeezed

If your child’s dehydration gets worse and they go into shock they may:

  • have pale or mottled skin
  • have cold fingers and toes
  • have low blood pressure
  • not be fully conscious

 Make sure your child gets urgent medical attention if they have these signs – they may need to be admitted to hospital.

5. How can I reduce the risk of getting gastroenteritis while abroad?

Be careful about what you eat and drink while on holiday to reduce your chance of getting ill.

Infections can be picked up from contaminated food and water. While away, be especially careful by:

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

Before travelling abroad, plan what you can take with you in case you become ill. You may wish to take oral hydration salts (eg Dioralyte) or antidiarrhoea tablets (eg Imodium).

Also, make sure you get any travel vaccinations that you need before you go. Book an appointment at your GP surgery or a travel clinic four to six weeks before you travel. However, if you’re travelling sooner, it’s still worth booking an appointment.

If you have any questions or concerns, talk to your travel health adviser, GP or pharmacist before you go abroad.

This information was published by Bupa Group's Health Content Team and has been reviewed by appropriate medical or clinical professionals. To the best of their knowledge the information is current and based on reputable sources of medical evidence, however Bupa (Asia) Limited makes no representation or warranty as to the completeness or accuracy of the Content.

The information on this page, and any information on third party websites referred to on this page, is provided as a guide only.  It should not be relied upon as a substitute for professional medical advice, nor is it intended to be used for medical diagnosis or treatment. Bupa (Asia) Limited is not liable for any loss or damage you suffer arising out of the use of, or reliance on, the information.

Third party websites are not owned or controlled by Bupa and any individual may be able to access and post messages on them. Bupa is not responsible for the content or availability of these third party websites.

Further information

Sources

  • Overview of gastroenteritis. MSD Manual. www.msdmanuals.com, published July 2015
  • Gastroenteritis in adults and older children. PatientPlus. www.patient.info/patientplus, published December 2014
  • Gastroenteritis in children. PatientPlus. www.patient.info/patientplus, published December 2014
  • Viral gastroenteritis. BMJ Best Practice. www.bestpractice.bmj.com, published February 2015
  • Food poisoning. BMJ Best Practice. www.bestpractice.bmj.com, published October 2015
  • Gastroenteritis. NICE Clinical Knowledge Summaries. www.cks.nice.org.uk, published August 2015
  • Lactose intolerance. PatientPlus. www.patient.info/patientplus, published December 2013
  • Oral rehydration salts. Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press. www.medicinescomplete.com, accessed August 2015
  • Probiotics and prebiotics. PatientPlus. www.patient.info/patientplus, published April 2015
  • Loperamide. Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press. www.medicinescomplete.com, accessed August 2015
  • Map of Medicine. Diarrhoea in adults. International View. London: Map of Medicine; 2016 (Issue 4)
  • Bacterial gastroenteritis clinical presentation. Medscape. www.emedicine.medscape.com, published October 2015
  • Diarrhoea – antibiotic associated. NICE Clinical Knowledge Summaries. www.cks.nice.org.uk, published June 2013
  • Viral gastroenteritis. Medscape. www.emedicine.medscape.com, published December 2014
  • Food poisoning. BMJ Best Evidence. www.bestpractice.bmj.com, published October 2015
  • Traveller’s diarrhoea. The Merck Manuals. www.merckmanuals.com, published July 2015
  • General advice for travellers. Travel Health Pro. www.travelhealthpro.org.uk, published October 2015
  • Fitness to work. Food Standards Agency. www.food.gov.uk, accessed 9 December 2015 
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