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Food poisoning: symptoms, causes and treatment

Young girl in bed with a thermometer in her mouth
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Most people experience food poisoning at least once in their life, whether it’s a one-off reaction or a week-long bout of vomiting and diarrhoea. The good news is that food poisoning is rarely serious and usually gets better on its own within a week, without the need for any treatment.

Symptoms of food poisoning

Food poisoning symptoms vary from person to person, but will typically include:

  • Nausea
  • Diarrhoea e.g. three or more loose and watery stools in 24 hours
  • Vomiting, which may only last one or two days
  • Stomach cramps
  • Fever and chills
  • Generally feeling unwell e.g. having aches and pains

After the sickness and diarrhoea has passed, you’ll probably feel very tired and drained, and not have an appetite for a few days.

It’s normal for food poisoning symptoms to start within a few hours or days of eating the food responsible. However, sometimes symptoms don’t set in for a few weeks, and in some cases, food poisoning can lead to dehydration.

Dehydration from food poisoning

Dehydration is a common side effect of food poisoning, especially if the illness is accompanied by sustained diarrhoea and vomiting. A person suffering from dehydration will often experience the following symptoms:

  • Tiredness and weakness
  • Feeling dizzy and lightheaded
  • Urinating less
  • Dark yellow urine that smells strong
  • Headaches
  • Muscle cramps
  • Dry mouth and tongue

If you think you’re becoming dehydrated, you should get medical advice as soon as possible. Mild dehydration is easy to treat, but if it progresses it can be life-threatening.

Causes of food poisoning

Food poisoning is exactly what it sounds like – consuming food that’s been contaminated with a harmful germ or toxin. There are lots of reasons why food might become contaminated:

  • It hasn’t been stored correctly e.g. milk that hasn’t been refrigerated
  • It hasn’t been cooked properly e.g. undercooked chicken that’s pink in the middle
  • It was prepared by someone who didn’t wash their hands
  • It was prepared in the same area as other foods like raw meat – this is called cross-contamination
  • It was washed with contaminated water – this is more likely to be a problem in countries with poor sanitation
  • It’s a dairy product made with unpasteurised milk

Infections that cause food poisoning

Food poisoning can be caused by bacteria, viruses and parasites, as well as toxins and chemicals. In the UK, the most common cause of food poisoning is campylobacter bacteria. Other infections that can cause food poisoning include:

  • Salmonella
  • E. coli
  • Norovirus
  • Toxoplasma gondii

How to avoid food poisoning

If you want to avoid food poisoning, you’ll need to make sure that you’re following some simple rules for hygiene and food preparation, including the following:

  • Wash your hands with soap and water before and after handling food, and after touching anything dirty or going to the toilet.
  • Use separate chopping boards for different foods e.g. one for raw meat and fish, and one for vegetables.
  • Keep raw meat and fish away from other foods, and store it on the bottom shelf of the fridge.
  • Clean counters, knives, utensils and chopping boards with hot, soapy water.
  • Replace dirty dishcloths and tea towels regularly, washing used ones in hot water.
  • Cook all your food thoroughly e.g. make sure meat is cooked until it’s hot all the way through and there are no pink areas when you cut into it.
  • Keep your fridge below 5°C and don’t overfill the shelves or leave the door open for long periods.
  • Get leftovers from hot meals in the fridge or freezer as soon as possible (ideally within 90 minutes) and eat them within two days.
  • Stick to the use-by dates on your food labels!

Avoiding food poisoning while travelling

When you’re travelling abroad it can be a bit harder to steer clear of food poisoning, especially in countries with poor sanitation. Some simple tips include washing your hands regularly, avoiding seafood or pink meat, and sticking to bottled water.

More tips can be found in this article: How to avoid travellers’ diarrhoea.

How to treat food poisoning

If you’re sick with diarrhoea and vomiting, the first thing to know is that you should stay home, so there’s no risk of the illness spreading. The NHS advises that you stay home from school or work until you haven’t had diarrhoea for at least 48 hours.

Most cases of food poisoning will pass on their own within a week and can be managed at home by doing the following:

Help from a pharmacist

A pharmacist can help if you think you might be getting dehydrated, or having a bout of diarrhoea. They might offer oral rehydration sachets or a tablet to help with the symptoms.

Find your local LloydsPharmacy

Prolonged and severe food poisoning

There are some circumstances where it’s important to get medical advice for food poisoning – you can do this by making an appointment with your GP, using the Online Doctor service VideoGP, or calling 111. In emergency situations, you’ll need to call 999 or go to A&E.

You should call 111 if:

  • You’ve had diarrhoea for more than seven days, or vomiting for more than two days
  • You’re having bloody diarrhoea or you’re bleeding from your bottom
  • You keep being sick and can’t keep any fluids down
  • You’re still showing signs of dehydration after using oral rehydration sachets

You should call 999 or go to A&E if:

Online Doctor VideoGP

References

www.nhs.uk/conditions/food-poisoning
https://patient.info/digestive-health/diarrhoea/food-poisoning
www.nhs.uk/conditions/dehydration
www.nhs.uk/live-well/eat-well/10-ways-to-prevent-food-poisoning
www.nhs.uk/conditions/diarrhoea-and-vomiting