Many people in the modern world, it’s probably fair to say, do not take food poisoning particularly seriously. Yes, most folks wash their hands after handling raw chicken and use different chopping boards for beef and green beans – but who among us can honestly say we’ve never used the same tongs for an entire barbecue or left a storage box of cooked rice on the sideboard for a couple of hours? Ignore that rhetorical question for a moment, though – before you comment that of course everyone should do all those things, let’s talk about what’s happening in your body when it all goes horribly wrong.
At the risk of stating the obvious, food poisoning occurs when you eat food contaminated with harmful bacteria, viruses or toxins – but that doesn’t mean it always works the same way. “Some bacteria, such as Bacillus cereus – sometimes found in reheated rice – produce toxins before the food is eaten, meaning they can cause symptoms such as sudden vomiting within hours,” says Dr Masarat Jilani, an NHS specialist who regularly manages children and adults with food poisoning. Bacillus cereus also produces another type of toxin in the small intestine, which can cause diarrhoea. “Others, such as Salmonella and E. coli, act after you’ve eaten and often cause longer-lasting symptoms through inflammation of the gut.”
Technically speaking, then, an expert might be able to guess what type of bacteria or virus you have ingested based on how quickly you become ill after eating. But in practical terms, that rarely happens.
“All of these bacteria work in different ways,” says Dr Emma Doughty, an infectious disease scientist. “Campylobacter jejuni bacteria, which you often find in poultry, are spiral-shaped and corkscrew their way through your gut lining. That’s different from, say, Shigatoxigenic E. coli, which excretes Shiga toxins. Both make you sick with gut inflammation and diarrhoea.” This means that, even though there are some effective treatments for food poisoning, such as antibiotics, it is not always easy for doctors to know which to prescribe.
“If you’ve got a stomach bug and you go to the doctor, typically they’re not going to give you antibiotics,” says Doughty. “The reason for that is that if you’ve got the Shiga toxin-producing variant of E. coli, and if you then kill all those bugs with antibiotics, they’re just going to release all the toxins inside them and make you even more sick. So without a specific infection diagnosis, it’s quite often safer to just let things get better on their own.”
Beware the bacteria … they can lurk in every crevice. Photograph: Kinga Krzeminska/Getty Images
What should you be doing to avoid all this unpleasantness? “Some of the most classic advice is still relevant,” says Doughty. “Oysters are always a risk, as is eating any kind of raw meat – there’s been a vogue for people to eat medium-rare burgers recently, which is a bit troubling.” To explain: if you are about to eat beef, you need to sear the parts that have been exposed to air to kill most of the bacteria likely to be living on it. With steak, that just means the outside, but with mince, that’s almost all of it.
Washing chicken – still bizarrely popular on TikTok – is an absolute no-no, as it’s likely to spread bacteria all over your kitchen and utensils, rather than reducing your chance of infection. Obviously, you should be keeping things clean, keeping raw meat separate from other food, quickly cooling cooked food and refrigerating it within two hours of cooking, and ensuring food is properly cooked, perhaps using a meat thermometer. “As with a lot of other infections, washing your hands is really valuable to prevent getting sick,” says Doughty. “In this case, it means washing your hands thoroughly after handling food, and after using the toilet.”
If it all goes wrong, most people won’t have too much to worry about, assuming they aren’t in an at-risk population. “The main risk from food poisoning is dehydration, which is why it is important to drink plenty of water and supplement with oral rehydration salts when you are experiencing it,” says Jilani. “Reintroducing a balanced diet is also important for recovery, and in the initial stages we often recommend a Brat diet – bananas, rice, applesauce and toast – if you feel that you can’t reintroduce your normal one straight away.”
Beige food – bananas, rice, applesauce and toast, among other things – is best for an upset stomach. Photograph: a_namenko/Getty Images
In more extreme cases food poisoning can lead to sepsis, which can include symptoms such as a fast heart rate and light-headedness. If you feel this might be happening, call the GP straight away. “In a minority of cases, you might also develop post-infectious irritable bowel syndrome (IBS), which can be characterised by abdominal pain and bloating,” says Jilani. Again, see a doctor if it persists.
The good news is that most cases of food poisoning will clear up on their own in a few days, as your immune system sorts them out. Just be more careful with the tongs next time.
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