Knowing when to go to the E.R. can be tricky

DEAR DR. ROACH >>

I recently had an episode of food poisoning with vomiting and diarrhea. It lasted four hours. I live alone. I’m 84, and in good health except for chronic atrial fibrillation and well-controlled high blood pressure. My question is, When does it become serious enough to call a doctor, and how do I determine if it is one of the serious strains that results in hospitalization? I don’t want to go to the emergency room unnecessarily. — B.R.

ANSWER >> Foodborne illness — that is, disease passed by contaminated food or water — is something that most people will suffer one or more times in their life. Bacteria, viruses and parasites all may be the source of foodborne illness. These germs may cause symptoms due to a toxin they make or they may invade the system. In general, toxin-mediated illness comes on faster and tends not to have fever. Invasive organisms usually take at least 24-48 hours to start causing symptoms, may cause fever or bleeding and tend to last longer. However, both kinds can be serious.

Although most cases of “food poisoning” will go away by themselves, there are some worrisome symptoms and signs that should raise concern and should make it more important for you to seek urgent care.

For most people, the biggest risk is losing too much fluid. This is called volume depletion or dehydration. Diarrhea can cause an enormous fluid loss that a person might not recognize. When combined with vomiting, the risk becomes serious, especially since the person cannot replace those lost fluids. Fever also causes increased fluid loss, and a temperature over 38 C/100.4 F should prompt concern. Finally, blood in the diarrhea or vomit should prompt a visit to your doctor, urgent care center or emergency room.

Being older is a significant risk — as is being very young; infants and toddlers are at increased risk — so keep that in mind when deciding whether to seek medical attention. Atrial fibrillation causes at least modest but sometimes significant reduction in your body’s ability to withstand volume depletion. Because of your age and atrial fibrillation (an abnormal heart rhythm), you should adhere to a much lower threshold for calling your doctor than a younger person with no chronic conditions.