What is food poisoning?

Food poisoning is an illness of the stomach and intestines caused by consuming food or drink that is contaminated with bacteria, viruses or toxins. Symptoms can start within hours of eating contaminated food and often include nausea, vomiting, stomach cramps and diarrhoea. Generally, food poisoning lasts between a few hours to a few days. Most often it resolves without treatment, however in severe cases can cause long-term health conditions or even death.

Food poisoning symptoms

Food poisoning can range from mild to severe, and symptoms are often similar those of gastroenteritis (gastro). Unlike gastro however, the onset of food poisoning symptoms is often sudden and dramatic – usually within 1-6 hours of ingestion1. Generally symptoms come and go quite quickly.

Depending on the type of food poisoning someone has, some or all of these signs and symptoms may be experienced:

• Nausea

• Vomiting

• Diarrhoea

• Abdominal cramps or pain

• Headache

• Fever or chills

• Loss of appetite

• Tiredness

• Weakness

Food poisoning symptoms can become life-threatening. If you experience any of the following symptoms, seek medical help immediately:

• Very high fever (38℃ or over)

• Blood in urine

• Blood or mucus in vomit or diarrhoea

• Diarrhoea longer than 3 days

• Frequent vomiting

• Unable to keep any fluids down longer than 24 hours after becoming ill

• Signs of severe dehydration (e.g. dry mouth, not drinking any liquids, passing little or no urine, weakness, dizziness)

How long does food poisoning last?

It depends on the type of food poisoning someone has, but usually food poisoning symptoms last 24-48 hours. Symptoms may pass within a few hours, or persist longer depending on the cause, how much contaminated food was eaten, and the severity of symptoms. If symptoms persist longer than 3 days, you should seek medical help immediately.

What causes food poisoning?

Often when people think of food poisoning, you may think of raw chicken or spoiled seafood. Different bacteria and viruses will have different effects.

There can be many causes of food poisoning, such as:

Certain wild mushrooms (e.g. Deathcap) can also be highly poisonous – avoid eating any mushrooms unless identified as safe and seek emergency medical attention if you think you have eaten a poisonous mushroom.

How does food become contaminated?

Food can easily be contaminated with bacteria, toxins or viruses that may grow and spread if it’s incorrectly stored, handled or cooked. Bacteria that occurs in food can cause food poisoning in two ways – either multiplying in sufficient numbers to make you ill or, or by producing poisons in the food as they multiply, which causes illness.

Food may be contaminated through:

• Lack of hand washing or not wearing gloves to prepare food – this can result in bacteria from faeces or raw meat being transferred to food

• Storing food at unsafe temperatures which allows bacteria to grow and spread

• Cross-contamination of raw meat coming in contact with ready-to-eat food (e.g. when a knife or chopping board used for raw chicken is used to prepare a salad)

• Re-heating leftovers several times – food bacteria start to multiply when chilled food is reheated to temperatures above 5ºC

• Cooking food and not refrigerating quickly enough can allow bacteria that survived the cooking process to multiply as the food cools down

• Fresh fruit, vegetables or eggs being contaminated with animal manure or water contaminated with animal manure

• Not cooking food (particularly raw meat) at high enough temperatures or for long enough

• Contact with pets, flies or other pests

• Food is touched by someone sick with viral gastroenteritis

Who is at high risk with food poisoning?

Certain people are at higher risk of dehydration or other serious complications resulting from food poisoning, particularly those with a weaker immune system. If you’re in one of these groups and notice symptoms of food poisoning or of a mild flu, contact your GP immediately*:

• The elderly

• Infants or babies

• Pregnant women – listeria can cause miscarriage

• People with chronic disease or a compromised immune system

How to prevent food poisoning

The best way to avoid food poisoning is by minimising your risk of getting it in the first place:

• Wash hands thoroughly and frequently with soap and running water

• Wash utensils, food surfaces and chopping boards frequently

• Separate raw foods and ready-to-eat foods, and ensure they are not prepared on the same surfaces

• Cook foods at safe temperatures – a food thermometer can help with this

• Refrigerate or freeze perishable foods immediately – food left at room temperature too long may develop bacteria or toxins which won’t be destroyed by cooking

• Check the expiry or best-before date on products

• If in doubt, throw it out

How to treat food poisoning

Food poisoning isn’t pleasant; however, symptoms often don’t last too long. While you wait for it to pass, there’s a few things you can do to make yourself more comfortable at home.

Treatment may include:

• Rest at home

• Drink water or suck on ice cubes if you’re finding it difficult to keep liquids down

• Oral rehydration or electrolyte drinks and products (such as icy poles) can help replace lost fluids

• Try to eat bland, easily digestible food

• Avoid taking any anti-vomiting or anti-diarrhoea medicine unless recommended by your doctor, as it may prevent any toxins or bacteria from being expelled from your body

In case your food poisoning is actually viral gastroenteritis (which has very similar symptoms, but is infectious), avoid seeing people or preparing food until after symptoms clear up.

When to see a doctor

Most food poisoning will pass relatively quickly without needing treatment. However, if you’re elderly, very young or pregnant, it’s important consult with a doctor.

In the case of children, contact your doctor if:

• Your child has had diarrhoea for more than a few days

• Has bloody diarrhoea

Dehydration is also another factor, so babies and infants who are unable to keep down liquids should be taken to a doctor straight away.

Visit an emergency department if:

• The symptoms of food poisoning are affecting a child is less than 12 months old

• Your child is vomiting, cannot keep down fluid and has acute abdominal pain

• They are showing signs of dehydration (producing little to no urine, lethargic, extreme thirst)

In the case of adults, consult your doctor if:

• Your symptoms have not cleared up after three days

• You are vomiting up fluids more than 24 hours after first showing symptoms

• Your vomit/diarrhoea shows signs of mucus/blood

Food poisoning can be an unavoidable part of life but our pharmacists are here to support you in managing your health. We can recommend a variety of products to help provide relief when you’re feeling unwell. Simply speak with one of our pharmacists about your symptoms, and we’ll suggest suitable products and medications tailored to your needs.

General advice only – this information should not replace the information provided to you by your health care professional. If symptoms are severe or persist, please speak to your health care professional. Information current as of date of publishing.

Resources:

>:https://www.healthdirect.gov.au/food-poisoning
*:https://www.mayoclinic.org/diseases-conditions/food-poisoning/symptoms-causes/syc-20356230#
#:https://www.healthywa.wa.gov.au/Articles/F_I/Food-poisoning
1:https://www.healthline.com/health/food-poisoning
2:https://www.mayoclinic.org/diseases-conditions/food-poisoning/symptoms-causes/syc-20356230#
3:https://www.foodstandards.gov.au/consumer/safety/faqsafety/documents/cool%20_and_reheat_food.pdf