Virus or food poisoning: Does it matter?

Even as we’re running to the bathroom in distress, we play medical detective: Food poisoning or a stomach bug?

But, medically speaking, does it really matter what’s causing that vomiting or diarrhea?

Often the answer is no, says Craig Cornwall, MD, an emergency medicine physician at Cape Cod Hospital.

“The treatment for us (in the ER) is to give fluids, get the vomiting controlled and then send patients home with appropriate medicine,” Dr. Cornwall said. “So, from my perspective, it doesn’t really matter which of the two you have. They are both self-limited and invariably go away with supportive care.”

Common Causes for Gastrointestinal Upset

As patients, we tend to blame one or the other. Stomach bugs, such as those caused by the norovirus, spread through personal contact or contaminated food and surfaces. They are making a comeback after dropping during the COVID-19 pandemic, according to the U.S. Centers for Disease Control, with at least 19 to 21 million annual cases, to say nothing of stomach issues caused by diseases such as influenza. Meanwhile, food poisoning holds its own with about 48 million cases reported annually, according to the CDC.

But for emergency clinicians, it’s less a choice about food poisoning vs. virus than it is about making sure it’s not something worse. If you show up in the emergency room or urgent care with vomiting, diarrhea, dehydration, high fever and pain, their first job is to rule out issues such as bacterial colitis or early appendicitis.

“From an emergency medical perspective, you’re trying to differentiate something more serious,” Dr. Cornwall said. “Is this something that might require antibiotics? Have you recently been on antibiotics? Have you recently traveled somewhere exotic? Have you been exposed to unusual foods?”

On the Cape, one of the more dangerous causes of food-borne illness is Vibrio, a bacterial toxin that’s usually associated with eating raw seafood, especially shellfish, Dr. Cornwall said. It can cause “quite aggressive” gastrointestinal issues, he said. “Patients can get quite sick quite quickly. So, if you’ve eaten undercooked seafood or anything like that recently, that’s a red flag for us.”

Testing and Treatments

Depending on symptoms and their duration, doctors may suggest blood tests or stool samples to look for infections such as E-coli that might require antibiotics. But the usual treatment for gastrointestinal upsets is lots of fluids along with anti-nausea or anti-diarrhea medication, he said.

These days, anti-nausea drugs such as Zofran, originally used for cancer patients, are readily available for all patients, he said. “It’s nice that there’s a version that dissolves on the tongue, so you don’t have to swallow it. It’s very effective with not too many side effects. That has definitely been a big game changer in terms of managing nausea and vomiting, both in the hospital and at home.”

If you’re still focused on what made you sick, one of the best clues is how long symptoms last, Dr. Cornwall said.

Food poisoning usually starts very abruptly, and the symptoms are likely to last only six or so hours. Since food poisoning is caused by toxins in food, things get better once the toxins are out of your system.

“A virus is a bit slower,” Dr. Cornwall said. “It tends to come on for two or three days, usually not as dramatically. It tends to have fever and chills, and oftentimes spreads among family members.”

When to Seek Medical Attention

No matter the cause, how do you know when it’s time to seek professional advice for tummy trouble? Get immediate help for adults or children who have any of these symptoms:

• If vomiting or diarrhea persist for more than three days;
• If there’s blood in your stool or vomit;
• If there are signs of dehydration such as dark urine, lethargy, increasing thirst or lightheadedness. Remember that because their bodies are small, children get dehydrated more quickly than adults;
• If a high fever persists for several days.