It's all so familiar — the mad rush; the unnatural proximity to that lavender-scented porcelain bowl; and that moment of indecision as you weigh up which exit the unwelcome contents of your guts are more likely to take.

As you battle through waves of nausea and the temptation to simply drown yourself in the toilet, you search for answers. Why me? Why now? And who (or what) is to blame?

Your thoughts rest momentarily on the queasy-looking guy who sneezed all over you in the bank queue, before settling on your meal from the night before. But thoughts of that 'seafood surprise' are rudely interrupted by violent retching and the mantra: I will not think of food again. I will not think of food again. I will not think of food again…

'What goes down can also... '

Ah yes, the joys of food poisoning. Life's little reminder that restaurants are not to be trusted; cleanliness is next to godliness; and that what goes down can also come back up again.

The fine line between gastro and food poisoning can become a little blurry, because viruses (gastric flu is a virus) can be passed from one person to the next through food. In the case of food poisoning, viruses are usually transmitted through faecal contamination of food. Generally food poisoning is caused by bacteria, but it can also be caused by parasites and toxins (usually found in mushrooms and exotic seafood).

Food poisoning symptoms usually begin unexpectedly within 48 hours of consuming the contaminated food, while gastro has a more gradual onset preceded by general achiness and tiredness a few days before the upset stomach sets in.

Symptoms

Typical food poisoning symptoms include nausea, vomiting, abdominal cramping and diarrhoea. Depending on the type and severity of the poisoning, they can also include a fever, bloody stools and nervous system damage.

Generally food poisoning is not dangerous and passes by itself within 48 hours, with the biggest threat to your health being severe dehydration. However there are certain types, such as botulism (caused by the bacterium Clostridium botulinum), which can be fatal. Symptoms of botulism include blurred vision, slurred speech, difficulty swallowing and muscle weakness.

What to do

The most important thing to remember if you have food poisoning is to make sure that you are properly hydrated. Vomiting and diarrhoea can quickly lead to dehydration and you need to replace the lost fluids.

Avoid food while you are nauseous or vomiting, but drink plenty of fluids. Avoid caffeinated and sugary drinks as these are likely to worsen your condition. Dilute fruit juice or energy drinks so that the sugar does not make your diarrhoea worse. Clear fluids are generally preferable.

If you are feeling particularly dehydrated, or have lost a lot of fluid, you can get over-the-counter oral rehydration solutions which help replace the lost electrolytes. Or you can mix up your own (rather vile-tasting but effective) solution by mixing one level teaspoon of salt with four heaped teaspoons of sugar in a litre of water.

Over-the-counter medications for nausea, vomiting and diarrhoea are generally safe to take and will provide some relief and prevent further dehydration.

Once you can stomach food again, opt for small amounts of simple foods such as rice, bread and potatoes.

Go to the doctor if:

  • Your symptoms last for more than two days.

  • Your child is younger than three.

  • You have a persistent or high fever.

  • You cannot keep liquids down.

  • You have a disease (such as HIV) which affects your immune system.

  • You can't take other prescribed medication because of the vomiting/diarrhoea.

  • You experience muscle weakness, blurred vision or slurred speech.

  • You have jaundice (eyes or skin turns yellow).

  • You have recently been travelling.

Go to hospital if:

  • You pass out.

  • You have a particularly high fever.

  • Your abdomen swells.

  • You are vomiting blood or have bloody stools.

  • You have trouble breathing, speaking or swallowing.

Useful food facts

Food poisoning can be avoided by strict personal hygiene (yes, hand-washing is that important), adequate washing and cooking, and correct storage of food.

Admittedly, you don't always have complete control over the environment in which your food is prepared. However, this doesn't mean that you can't take a few precautions and avoid those foods which are more prone to carrying poisonous organisms — raw meat, undercooked poultry, raw milk and seafood (particularly shellfish and exotic fish).

Avoid any milk or dairy products (especially cheeses) that are made from unpasteurised (raw) milk. Pasteurisation is specifically designed to kill dangerous micro-organism.

Raw eggs occasionally carry bacteria (Salmonellae) in the yolk or white that can lead to food poisoning. It is best to eat properly cooked eggs (and poultry) and avoid recipes which include raw eggs.

Water that has been contaminated by sewerage is dangerous and a common cause of food poisoning. All fruit and vegetables should only be washed in potable (drinkable) water. If in doubt add Milton's disinfectant or a small amount of bleach to the water. If you are travelling and are uncertain about the drink-ability of the water, opt for bottled water instead.

Improperly canned foods can occasionally lead to food poisoning (most notably botulism), so make sure that you never eat foods which have exceeded their sell-by date or have been stored improperly.

And finally, if the food looks, smells or tastes odd, throw it away immediately!