Food poisoning - including symptoms, treatment and prevention

Food poisoning is an illness caused by eating contaminated food. The most common sources of contamination are bacteria or toxic substances produced by bacteria. Some viruses and fungi can also cause food poisoning.

Food poisoning is a notifiable condition1

How food poisoning occurs

Bacteria may contaminate food as a result of farming or other production methods or poor preparation, handling or storage of food. Contaminated food may not look, smell or taste any different from food that is safe.

Signs and symptoms of food poisoning

Typical symptoms are a sudden onset of:

  • nausea
  • vomiting
  • stomach cramps
  • diarrhoea. 

The illness usually lasts from less than 24 hours to several days depending on the cause. Occasional severe cases last longer and may require hospitalisation.

While single cases of food poisoning undoubtedly occur, they are difficult to detect and frequently go unreported. Food poisoning is usually recognised as a typical illness occurring in a group of people shortly after eating a common food.

Diagnosis  of food poisoning

Detection of large numbers of certain bacteria in suspect food samples and detection of the same bacteria in samples of faeces from affected people confirm the diagnosis of food poisoning.

Incubation period

(time between becoming infected and developing symptoms)

Varies depending on the cause, but usually from a few hours to a few days. Although many ill people blame a food they ate before they got ill, experience indicates that this food is usually not the cause of the illness.

Infectious period

(time during which an infected person can infect others)

Depends on what has caused the illness. Not all causes of food poisoning are able to be spread from person-to-person, but some are.

Treatment for food poisoning

Treatment varies depending on what is the cause of the food poisoning. Usually these illnesses do not require antibiotic treatment.

Preventing food poisoning

If the cause is not known, it should be assumed that it may be possible to spread from person-to-person, or for an infected person to contaminate food and indirectly infect others. Therefore:

  • Exclude people with food poisoning from childcare, preschool, school or work until there has been no diarrhoea or vomiting for at least 24 hours. If working as a food handler in a food business, the exclusion period should be until there has been no diarrhoea or vomiting for 48 hours
  • follow good hand washing and keeping areas clean procedures
  • good food handling procedures should always be followed
  • do not allow people affected by food poisoning to prepare food for others until there has been no diarrhoea or vomiting for 24 hours
  • infants, children and adults with diarrhoea from food poisoning should not swim until there has been no diarrhoea for 24 hours
  • babies and small children without diarrhoea who are not toilet trained should wear tight fitting waterproof pants or swimming nappies in swimming pools and changed regularly in the change room. When faecal accidents occur, swimming pools should be properly disinfected.

Useful links

1 - In South Australia the law requires doctors and laboratories to report some infections or diseases to SA Health. These infections or diseases are commonly referred to as 'notifiable conditions'.