Stomach Flu, Food Poisoning and Glutening Symptoms

It can be tricky to tell the difference between symptoms of the stomach flu or food poisoning and symptoms of a glutening. In many cases, the symptoms overlap quite a bit:

  • Diarrhea
  • Stomach pain
  • Fatigue
  • Headache

You can watch for a few key clues that may help you determine what's going on, and whether or not you should call your healthcare provider.

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Stomach Flu and Food Poisoning Start Suddenly

Despite its name, the "stomach flu" isn't really a form of the respiratory illness influenza. The technical name for stomach flu is gastroenteritis, and the condition is usually caused by a virus that invades your body and sets up shop in your intestinal tract.

Symptoms generally come on suddenly (and in some cases dramatically), and can include aforementioned diarrhea, stomach pain, and cramps, nausea, vomiting, fever, chills, and weakness.

The stomach flu usually runs its course within three or four days and usually doesn't require prescription medication. In some cases, symptoms might persist for more than a week, although they usually begin to taper off after a day or two.

Food poisoning, meanwhile, results from bacterial contamination in the food you've eaten. The symptoms are similar to stomach flu, and also come on suddenly: abdominal pain and cramps, nausea, vomiting, diarrhea, and fever.

It's possible to treat some forms of food poisoning with antibiotics, but many infections will clear by themselves within a week.

Glutening Symptoms Stem From Cross-Contamination

If you're new to the gluten-free diet, you may initially be surprised at how badly your body reacts to accidental gluten cross-contamination, especially if you didn't have bad symptoms prior to your diagnosis with celiac disease or non-celiac gluten sensitivity.

It can be tricky to generalize about what happens when you get glutened because everyone's symptoms are a little different. However, given time (and known glutenings), you can figure out your usual pattern of symptoms. That can help you differentiate them from symptoms of stomach flu and food poisoning.

Here are some clues:

  • Vomiting. Only a minority of people experience vomiting from gluten ingestion — it seems to be most common in children, and in cases where you've eaten a lot of gluten (think: a slice of cake). Yes, gluten can cause nausea and vomiting, but it doesn't happen that often. Small amounts of gluten cross-contamination are unlikely to cause vomiting (although it is possible). Therefore, if you're vomiting (and especially if you're vomiting frequently), you're more likely to be suffering from gastroenteritis or food poisoning unless you know for certain that you ate gluten in large quantities.
  • Fever. The stomach flu frequently causes fever, and food poisoning also usually results in a fever. Although there have been some anecdotal reports from people who say they experience fever from accidental gluten ingestion, there's little in the medical literature to support this. Therefore, if you have a fever with your other symptoms, you're more likely to have stomach flu or food poisoning.
  • Skin symptoms. Many people get skin symptoms from accidental gluten ingestion. Dermatitis herpetiformis is common, but others experience flare-ups of eczema, psoriasis or even acne. If your symptoms include a rash or other skin symptoms, the cause probably is gluten, not gastroenteritis or food poisoning.
  • Constipation. The stomach flu and food poisoning both typically cause diarrhea, and of course, gluten can cause diarrhea, too. But a large minority of people with celiac or gluten sensitivity actually suffer more from constipation, not diarrhea. If you typically get constipated from known gluten ingestion, then diarrhea is more likely to indicate you've picked up a bug.
  • Insomnia and brain fog. Many people experience gluten-related neurological symptoms such as brain fog and insomnia. Stomach flu and food poisoning both cause fatigue (you're likely to be exhausted and just want to sleep), but they shouldn't cause insomnia. Brain fog also is unlikely from the stomach flu or food poisoning. Therefore, if you have insomnia and/or brain fog, the more likely cause is gluten.

If in Doubt, Call Your Healthcare Provider

Determining your particular cascade of gluten symptoms will take some time, especially if your diagnosis was recent. As you figure it out, it's likely you'll have some instances where you're just not certain why you're feeling the way you do.

If your symptoms are severe, don't hesitate to call your healthcare provider's office and ask the nurse there if you should come in.

If you begin to vomit blood, see large amounts of blood or mucus in your stool, experience serious confusion or lightheadedness, or have a fever higher than 101 F, you should seek immediate medical attention.

If on the other hand, your symptoms are manageable and your fever is low or non-existent, you can simply stay at home, take it easy and wait it out. Regardless of whether you've been glutened, have the stomach flu, or have food poisoning, you can learn how to recover from a glutening, which might help you feel better.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases. Symptoms & Causes of viral Gastroenteritis ("Stomach Flu").

  2. Centers for Disease Control and Prevention. Food Safety: Food Poisoning Symptoms.

  3. National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases. Treatment for Food Poisoning.

  4. National Institutes of Health. National Institute of Diabetes and Digestive and Kidney Diseases. Symptoms & Causes of Celiac Disease.

  5. Zylberberg HM, Demmer RT, Murray JA, Green PHR, Lebwohl B. Depression and insomnia among individuals with celiac disease or on a gluten-free diet in the USA: results from a national survey. Eur J Gastroenterol Hepatol. 2017;29(9):1091–1096. doi:10.1097/MEG.0000000000000932

  6. Celiac Disease Foundation. "Brain Fog" Improves in Celiac Disease Patients After Starting a Gluten-Free Diet.

Additional Reading

By Jane Anderson
Jane Anderson is a medical journalist and an expert in celiac disease, gluten sensitivity, and the gluten-free diet.