Food poisoning occurs when food contaminated with infectious organisms causes illness.

Food poisoning is a very common condition where a person falls ill as a result of eating contaminated foods containing bacteria, viruses or parasites.

Some of the more common bacterial food poisoning causes are:

  • E. coli (often spread through undercooked beef mince)
  • Salmonella (usually spread via undercooked poultry products or through unpasteurised milk)
  • Listeria (spread via processed meats and soft cheeses)
  • Campylobacter (contaminated meat and poultry)
  • Norovirus (usually spread from raw shellfish and between people) is the most common viral type of food poisoning.

What are its symptoms

Food poisoning symptoms include:

  • Nausea
  • Vomiting
  • Diarrhoea
  • Abdominal cramping and pain
  • Fever
  • Loss of appetite
  • Lethargy and general feeling of being unwell
  • Muscle aches
  • Chills

Onset of the symptoms of food poisoning is usually within one or two days of ingesting the contaminated food, but they can come on within hours or take as long as several weeks. Symptoms can last from a few hours to several days.

It is important to seek medical assistance if the affected person is showing signs of being dehydrated, is unable to keep down liquids, has had diarrhoea for more than three days, or if there is blood in the vomit or stools.

How is it diagnosed?

A food poisoning diagnosis usually relies on a medical history, a look at when the patient fell sick, how long they have been sick and what was eaten leading up to the point at which they became ill, as well as a physical examination.

Further tests may be conducted to confirm the diagnosis, as well as to identify the organism responsible. These tests may include blood tests or stool cultures, which will then be sent to a laboratory for further testing.

What are your treatment options?

Depending on the causative organism, food poisoning treatment is often largely symptomatic and the illness will usually resolve itself within a few days. 

Certain types of bacterial food poisoning such as listeria may require antibiotics, but for most other types recovery at home for a few days is usually sufficient.

Your healthcare practitioner may recommend anti-emetics to curb vomiting in severe cases and oral rehydration solutions, which are available over the counter, to replace lost fluids and electrolytes.

If persistent diarrhoea and vomiting are interfering with rehydration efforts, hospitalisation may be required to replace fluids intravenously. 

Can it be prevented?

Avoiding contaminated foods is key to food poisoning prevention. Safe food preparation and handling as well as storage guidelines should be adhered to in order to reduce risk. Here’s how to put them into practice in your home:

  • Wash hands before and after food preparation. Use clean work surfaces and utensils.
  • Ensure that food is properly cooked, particularly meat and seafood, as heat kills bacteria.
  • Avoid cross-contamination. This includes storing different foods separately.
  • Keep perishable foods in the fridge or freezer, making sure to put them there promptly; being left at room temperature allows bacteria to multiply rapidly and not all bacteria are killed by cooking.
  • Use food by its expiry date. In the case of leftovers, keep to the maxim: “When in doubt, throw them out.” Also discard food left unrefrigerated for too long.
The accuracy of this information was checked and approved by physician Dr Thomas Blake in December 2015