Health conditions

Food poisoning

Food poisoning is any illness caused by eating food or drink that is contaminated with certain types of bacteria, parasites, viruses or toxins.

Symptoms can vary from mild to severe. Some people are at more risk of getting food poisoning than others, including the elderly, young children, pregnant women and people with weakened immune systems.

How does food become contaminated?

Food can become contaminated:

  • when food is not prepared safely, including when meat is undercooked or lack of hand washing
  • when food is touched by someone who has gastroenteritis (gastro)
  • by contact with pets, flies or other pests
  • when raw meat and ready to eat foods come into contact with each other
  • when food is stored at unsafe temperatures that allows bacteria to grow
  • when fruit, vegetables and eggs are contaminated with animal manure or water contaminated by animal manure.
Signs and symptoms

People with food poisoning may experience some or all of the following symptoms:

  • nausea (feeling sick)
  • diarrhoea
  • vomiting
  • stomach pains or cramps
  • sweating, fever or chills
  • headache
  • lethargy (extreme tiredness).

The symptoms of food poisoning vary depending on the cause of the illness after eating contaminated food (incubation period).

The symptoms of food poisoning are often the same as the symptoms of viral gastro that is more often due to contact with another ill person (person to person spread) or contaminated surfaces.

Types of food poisoning

Some of the common types of food poisoning, with symptoms and incubation period are shown below. The foods shown have previously been found to be a source of food poisoning, but this does not mean that food poisoning organisms are always found in these foods or that they are always unsafe to eat.

This table is for guidance only. Seek medical advice for a diagnosis.

Type of food poisoning Symptoms Incubation period Associated foods
Botulism Blurred vision, difficulty in speaking, swallowing and breathing, nausea, vomiting, dry mouth, weakness, fatigue and ultimately paralysis. 12 to 36 hours Honey, home-preserved fruits, vegetables, potato salad, minced garlic in oil. Canned foods, meat, fish and soft cheeses.
Clostridium perfringens Diarrhoea, stomach cramps that last for about 24 hours. 8 to 22 hours Meat, poultry.
Campylobacter Diarrhoea, fever and abdominal pain. Symptoms last for about 5 days. 2 to 7 days Raw poultry and meat, contaminated water, unpasteurised milk.

Cholera (Infection normally obtained overseas)

Profuse, watery diarrhoea (characteristic ‘rice water’ faeces), nausea and vomiting, dehydration, fever, stomach cramps. Few hours to 5 days (usually 12 to 24 hours) Contaminated food and drink, fish or shellfish from contaminated waters.
Cryptosporidiosis Watery to severe diarrhoea, stomach cramps, nausea, vomiting, fever, weight loss. Symptoms last for about 2 weeks. 2 to 10 days Uncooked food, fruit and vegetables.
Giardia infection Foul smelling greasy or watery diarrhoea, stomach cramps, nausea, fatigue, bloating, and loss of appetite. 7 to 10 days Uncooked food, fruit and vegetables.

Haemolytic uraemic syndrome (HUS) - see STEC

Diarrhoea, abdominal pain, vomiting and fever. 2 to 8 days Undercooked beef, unpasteurised milk, sprouts, contaminated water.

Hepatitis A (Infection normally obtained overseas)

Abdominal pain, fever. Tiredness, jaundice. 15 to 50 days Contaminated food and drink, fish or shellfish from contaminated waters.
Listeria infection Flu-like symptoms: fever, headaches and pains. May cause miscarriage and stillbirth. Symptoms are most likely to occur in vulnerable groups. 2 days to 3 months Soft cheese, unpasteurised milk, ready-to-eat deli meats.
Norovirus infection Nausea, vomiting, diarrhoea, stomach cramps, headache, low grade fever, chills, muscle aches. Lasts for 1 to 2 days. 1 to 2 days Mainly person to person spread. Also contaminated food or drinks, putting contaminated hands or fingers in mouth, sharing food or eating from the same utensils as someone who is ill.

Salmonellosis

 

Abdominal pain, nausea, diarrhoea, fever, vomiting and headache. 8 hours to 7 days (usually 12 to 36 hours) Raw chicken and meat, undercooked eggs, raw egg mayonnaise.
Shiga toxin producing E.coli (STEC) Diarrhoea, abdominal pain, vomiting and fever. Illness can develop into HUS. 2 to 8 days Undercooked beef, unpasteurised milk, sprouts, contaminated water.
Shigellosis Diarrhoea (usually containing mucus and/or blood), nausea and vomiting, fever, stomach cramps. Symptoms last about 4 to 7 days. 1 to 7 days (usually 1 to 3 days) Contaminated food, drink and objects. Person to person spread.
Staphylococcus aureus Nausea, vomiting, stomach cramps and diarrhoea. Last for about 1 to 3 days 1 to 6 hours Raw meat and poultry, cheese, cream, unpasteurised milk, processed meat.

Typhoid & Paratyphoid (Infection normally obtained overseas)

Typhoid: 8 to 14 days
Paratyphoid:1 to 10 days

Contaminated food or drinks, putting contaminated hands or fingers in mouth, sharing food or eating from the same utensils as someone who is ill.
Vibrio parahaemolyticus Diarrhoea, stomach pain, nausea and vomiting. May last several days. 4 to 30 hours Raw or undercooked fish and shellfish.
How do I know I have food poisoning?

Diagnosis must be made by a medical professional. See your doctor or go to hospital if you suspect you have food poisoning.

If you suspect you have food poisoning

Consult your doctor, especially if you have severe symptoms. It is particularly important for vulnerable people such as the elderly or young children to have immediate medical attention.

  • Drink plenty of water to avoid dehydration. Dehydration is especially dangerous for babies and the elderly.
  • As far as possible do not handle or prepare food for others until you are symptom free for 48 hours. This will prevent you from infecting others.
  • If you must handle food, wash your hands with soap and warm water and dry thoroughly to prevent cross-contamination.
  • If you work in food handling you are legally required to notify your employer. You must not handle food at work until you have been symptom free for 48 hours.
Treatment of food poisoning
Treatment varies with the type of food poisoning infection.
How can food poisoning be prevented?
Food safety and hygiene is essential in preventing food poisoning.

Where to get help

  • See your doctor
  • Visit a GP after hours
  • Ring healthdirect on 1800 022 222

Remember

  • Common symptoms of food poisoning include nausea, diarrhoea, vomiting and stomach cramps.
  • Viral gastroenteritis has similar symptoms to food poisoning.
  • See a doctor if you suspect food poisoning, particularly for young children, the elderly or the sick.

Acknowledgements

Public Health


This publication is provided for education and information purposes only. It is not a substitute for professional medical care. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your healthcare professional. Readers should note that over time currency and completeness of the information may change. All users should seek advice from a qualified healthcare professional for a diagnosis and answers to their medical questions.