Food poisoning

General information

Food poisoning is a sudden inflammation of the bowel caused by contaminated food or water. It is usually viral (e.g. norovirus), bacterial (salmonella) or a toxin generated by bacteria. Food poisoning can also be caused by chemicals, mushrooms, plants, parasites and animals. The most common route of infection is food that has not been prepared, stored, produced or served properly.

The symptoms usually appear within a day from exposure, but some bacteria take longer to cause symptoms. Food poisoning symptoms include diarrhoea, stomach cramps, nausea and vomiting. You may also have a high temperature.

Food poisoning usually clears up in 1–3 days.


The most important treatment is hydration. You should drink regularly up to several litres of fluids throughout the day, even if you can only manage small portions at a time. To maintain a good electrolyte balance, drink salty liquids as well through the day.

You can eat something light and easy to digest, although eating may give you stomach cramps. Food is absorbed almost normally despite diarrhoea. Going without solid food for a couple of days is not harmful as long as you take a variety of fluids that contain energy (weak juice, water, tea and broth). Liquids are absorbed as normal, despite diarrhoea.

Milk-based, caffeinated drinks and artificial sweeteners are NOT recommended. You should also avoid energy drinks.

Pharmacies sell rehydration solutions, which are easy to use at home. You can also prepare one at home: Mix 1 litre of fruit juice (preferably orange juice) with 1 litre of water and 1 teaspoon of salt. The natural sugar helps the water and salt to absorb.

Special attention should be paid to sufficient hydration of the elderly and children because they are not always able to say they are thirsty. If your urine is darker than normal, you may be dehydrated.

Wash your hands thoroughly and regularly and observe good kitchen and food hygiene. Pay attention to the temperature at which you store food and prepare food and to the suitability of the storage and preparation areas. Observe the best-before and use-by dates on food items.

When should you seek medical advice?

People who have been instructed to contact healthcare professionals even with milder symptoms due to an underlying illness or regular medication should do so.

Seek medical advice if

  • your symptoms began while abroad or soon after return from abroad
  • the diarrhoea/vomiting is very severe and you feel much worse than you usually do when sick
  • your temperature is higher than 38.5°C
  • there are clear signs of blood in your stools/vomit

If the diarrhoea and vomiting have lasted longer than one week and you have had a temperature for more than four days, you should seek medical advice.

If several people around you have similar symptoms, inform your local health centre by phone to alert them of a possible epidemic.

This Self-care instruction has been produced in collaboration with Duodecim Terveyskirjasto

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Updated  8.6.2020