Stomach Flu vs. Food Poisoning: How To Tell the Difference

While it's difficult to distinguish between food poisoning and the flu, the treatments are essentially the same.

You're racked by nausea, your stomach is doing flip-flops, and you don't dare leave the toilet. As you dash to the bathroom and anxiously ponder what is going on, two possibilities pop into your head: You've come down with the stomach flu or contracted food poisoning.

But how do you tell the difference? That's where things get tricky.

Similar Symptoms

"The stomach flu and foodborne illness are easy to confuse because the symptoms are almost identical," Niket Sonpal, MD,adjunct assistant professor of clinical medicine at Touro College of Osteopathic Medicine in New York City and Clinical instructor at Kingsbrook Jewish Medical Center in Brooklyn told Health.

Those symptoms include:

  • Severe nausea
  • Stomach cramps
  • Diarrhea
  • Vomiting

Of note, what is commonly called the stomach flu isn't related to the flu at all; the influenza virus causes the flu. Most stomach bugs are caused by norovirus. Norovirus is a family of highly contagious viruses that wreak ruthless havoc on your gastrointestinal tract, according to the Centers for Disease Control and Prevention (CDC). Norovirus is contracted by touching a surface where the bug is lurking and then touching your mouth via close contact with someone already infected or by eating food contaminated by someone carrying the virus.

Food poisoning, on the other hand, is an umbrella term for any of the more than 250 foodborne illnesses researchers have identified, according to the CDC. Bacteria, parasites, and viruses can cause them; norovirus transmitted through food could be considered a foodborne illness. Others include salmonella, which you can get from foods like undercooked poultry or meat, and listeria, which is linked to soft cheeses, raw bean sprouts, and melons.

While they are distinct illnesses that share many characteristics, norovirus and food poisoning have a few differences in their symptoms. These questions can help you decide which one you likely are dealing with.

Do You Have Other Symptoms Besides GI Issues?

While ongoing diarrhea and vomiting attacks are the main signs, stomach-flu sufferers can also have "additional extra-intestinal symptoms—things that happen outside your GI tract, said Dr. Sonpal. "These can be signs of dehydration like headache, lightheadedness, and dry mouth."

People with food poisoning can also experience non-gastrointestinal-related signs. According to the CDC, depending on the germ you've swallowed, you could also have flu-like symptoms that include

  • Fever
  • Increased gas
  • Slurred speech
  • drooping eyelids
  • loss of balance

Janette Nesheiwat, MD, a family and emergency physician and medical news expert in New York City, said that additional symptoms of food poisoning could include:

  • Weakness
  • Body aches
  • Rash

How Long Did It Take for the Symptoms to Show Up?

In general, according to the CDC, if you've picked up the norovirus germ, the first signs of the illness will appear within 12-48 hours.

For food poisoning, the timing of symptoms depends on several factors. If a microbe causes your symptoms, you might not feel bad until 3-4 days after consuming it in your food. But if the illness is caused by a reaction to a toxin released by the microbe, the discomfort comes on much faster. "Eat something in the morning, and you can have symptoms that afternoon," Van Pham, DO, a primary care physician at MemorialCare Medical Group in Long Beach, California, told Health.

What To Do When You're Sick With Either Illness

When treating the stomach flu, there's no magic pill that will make you instantly well. Instead, you've got to wait until your body thoroughly flushes norovirus from your system. The good news? Norovirus "is very self-limited and lasts 3 to 4 days for most people," said Dr. Pham.

If you have food poisoning, you'll also have to wait it out anywhere from a few hours to several days, according to the CDC, though this depends on the microbe causing your distress. Most people recover with no issues, but depending on the microbe ingested, there can be some potential long-term issues, including chronic arthritis, brain and nerve damage, and kidney failure, per the CDC.

While riding it out, it's crucial to keep drinking fluids that don't contain alcohol or caffeine, so you don't get dehydrated. If diarrhea or vomiting is severe, the CDC recommends sipping oral rehydration fluids (like Ceralyte, Oralyte, or Pedialyte) to replace your electrolytes and fluids. Sports drinks may help some, but they might not replace the proper nutrients and minerals. They're also high in sugar, which may make your diarrhea worse.

According to the National Library of Medicine's resource MedlinePlus, signs that you might not be hydrating enough include:

  • Feeling very thirsty
  • Dry mouth
  • Urinating less than usual
  • Dark-colored urine
  • Dry skin
  • Fatigue
  • Dizziness

Severe dehydration ramps up the symptoms to include:

  • Confusion
  • Fainting
  • Lack of urination
  • Rapid Heartbeat
  • Rapid Breathing
  • Shock

Children or infants who are dehydrated may cry with few or no tears and be unusually sleepy or fussy, per the CDC.

Dehydration is nothing to mess with. If you experience any symptoms of severe dehydration or have a child in your care who is showing signs of it, seek medical help immediately. And if things don't clear up or at any point, you experience a high fever, bloody diarrhea, diarrhea lasting more than three days, or you can't keep any fluids down, contact your healthcare provider or seek emergency or urgent care, per the CDC.

In the meantime, get as much rest as possible, stay as hydrated as possible, and watch for signs of more severe illness. And remember, whether you've contracted the stomach flu or food poisoning, this too shall pass.

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