Signs of Food Poisoning: How Do You Know If It's Food Poisoning or a Virus?

Few things are more unpleasant than a bad case of food poisoning. Even after you stop making trips to the toilet, you typically experience loss of appetite and fatigue for days. Food poisoning signs are similar to those of a viral infection called viral gastroenteritis, where infection with a virus causes inflammation of the lining of the stomach. This makes it difficult to know whether your vomiting and diarrhea comes from "something you ate" - or whether you picked up a viral infection. How can you tell the difference?

Signs of Food Poisoning: Could It Be a Virus?

Food poisoning is caused by eating food contaminated with bacteria or a bacterial toxin. Gastroenteritis has a variety of causes but in most cases it's caused by exposure to a virus. Diarrhea, nausea, vomiting, abdominal cramping and fever are common signs of food poisoning and of viral gastroenteritis, which means there are lots of people who think their food poisoning is "just a virus".

The problem is food poisoning can lead to complications involving other organs such as the kidneys, although this is more likely to occur in people with immune problems. Gastroenteritis from viruses is less likely to lead to more serious problems other than dehydration from too much vomiting and diarrhea. Making the distinction is important because of the greater risk of complications with food poisoning - and because you may have eaten the offending food at a restaurant and want to avoid it in the future.

Unfortunately, the signs of food poisoning resemble those of viral gastroenteritis so closely that you can't usually diagnose one or the other based on symptoms. You have to do some detective work. Did other people who ate with you become ill? If so, food poisoning is highly suspect. If you became ill after eating in a restaurant, you can contact the health department to see if there were any reported cases of illness originating from that restaurant.

A doctor can take stool cultures to look for evidence of bacteria that cause food poisoning, but most doctors don't routinely do them unless the symptoms persist beyond 3 days. Even more helpful is collecting a sample of the suspected food so it can be cultured for bacteria.

Fortunately, in most cases, it's not a major issue whether it's food poisoning or viral gastroenteritis since most people recover from both. The key is to avoid dehydration by drinking lots of fluids. Antibiotics aren't usually needed to treat the average case of food poisoning unless complications develop. Lots of rest and fluids is the best medicine for both, but if there are any signs of dehydration, it's time to see a doctor.

References:

Merck Manual. Eighteenth edition. 2006.