Gastroenteritis (adults)

Gastroenteritis (tummy bug, food poisoning, traveller's diarrhoea, viral enteritis or intestinal flu) is a gut infection that causes stomach cramps, vomiting and diarrhoea.

It is very common and is often caused by unclean food or water.

Your stomach upset may be due to:

  • a virus passed on by someone who may or may not have symptoms
  • bacteria from food that is not fresh or well-cooked, unclean water, hands, cooking or eating utensils.
  • Bacteria can also be spread by flies. Meat, poultry, dairy products, eggs, shellfish and parboiled rice are the most commonly affected
  • amoebas or parasites.


The infection irritates your stomach and gut making the muscles tighten, causing vomiting or diarrhoea. You can get sick from an hour to five days after getting infected, depending on the bug.

You may get cramps, have a gurgly, uncomfortable stomach, vomit and have watery diarrhoea. (If the faeces contain blood or pus you should contact your doctor). You may also feel sick, shivery, have a headache and/or fever. It usually only lasts a few days, but may last longer.

If you become very weak, have trouble waking up, have sunken eyes, go very pale, stop passing urine or get very dry skin and tongue, you may be dehydrated and need urgent attention.


Diagnosis is mostly by the symptoms. If they are very bad or not settling, the doctor may send a stool (faeces) sample to the laboratory.


See our topic on diarrhoea for self-help and treatment options for diarrhoea and/or vomiting (includes information on children and dehydration), and when to contact your doctor.

How can I protect myself and others?

undefinedHandling food

  • wash your hands before eating or preparing food and after going to the toilet
  • if you work with food commercially, use latex gloves and avoid touching food with the hands where possible
  • wash the tops of cans before opening
  • wash all utensils, boards and surfaces used for meat, poultry, etc with hot, soapy water
  • don't let raw food come in contact with these surfaces
  • if it smells bad or looks dodgy throw the food out.


  • buy perishable food only as you need it
  • get perishables home from the shops and stored/refrigerated quickly
  • check use-by dates
  • don't leave poultry or meat in their store wrappers for more than two days. Rewrap in wax paper or plastic wrap
  • when freezing, wrap tightly, date and use within six months.


  • never defrost frozen foods on the bench: thaw in the fridge, in warm water or the microwave or cook them from frozen
  • when thawing frozen meat in the fridge, ensure there is a plate underneath and preferably place the meat on the bottom tray of the fridge, to avoid contamination of other foods with meat juice or drips
  • cook food thoroughly, particularly meat, chicken, eggs, milk products, fish and shellfish
  • clean and cook chicken very well, pack stuffing loosely
  • serve hot food hot (most bacteria are killed at 100°C) and cold food cold (bacteria stop growing at 0°C but can survive). They grow extremely well between 15°C and 51°C
  • cool leftovers quickly and place in the fridge; ensure you reheat them thoroughly
  • avoid raw fish, meats and shellfish unless you are sure they are well prepared and from a reliable place.

Travelling/eating out

  • look at how clean the eating establishment is
  • be wary of food, even salad and cold cuts, that sit all day
  • in developing countries: don't eat raw food, food from street stalls or peeled fruits; drink only bottled or boiled water or drinks; avoid ice; use water purification tablets.
Credits: Health Navigator. Reviewed By: Health Navigator Last reviewed: 11 Feb 2015