A java chip frappuccino with breakfast. Thai chicken wrap for lunch. Aunt Susan’s famous pot roast for dinner.

If none of your go-to foods have been sitting well with you lately, you’re probably wondering what the problem is. Could it be a wheat allergy? Gluten sensitivity? Celiac disease? And what’s the difference between them, anyways?

Before you go down a WebMD rabbit hole, we asked a gastroenterologist everything you need to know about the three conditions.

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How can I tell if it’s celiac disease or a gluten sensitivity?

The short answer is, you can’t.

“Celiac disease and gluten sensitivity have exactly the same symptoms. It’s also possible to have celiac disease without any symptoms, so it’s important to see an expert for an accurate diagnosis,” says Sarah Canavan, MD, gastroenterologist at Backus Hospital.

In either case, common symptoms include:

  • Diarrhea
  • Nausea
  • Vomiting
  • Abdominal pain
  • Weight loss
  • Bloating
  • Gas
  • Constipation

But don’t rely on those symptoms alone for a diagnosis.

“It could be celiac disease, it could be a gluten sensitivity, it could be neither of those things. But if you’re having GI trouble, it’s crucial to find out what the culprit is before it worsens.”

> Related: 6 Reasons Why Your Stomach Hurts After Eating

A wheat allergy looks a little different.

Unlike celiac disease or a gluten sensitivity, a wheat allergy rarely causes gastrointestinal pain.

“This is a completely different thing. An allergy reaction is a different activation of the immune system,” Dr. Canavan notes.

This will present differently, and won’t occur without symptoms. These include:

  • Skin rash
  • Itching
  • Hives
  • Anaphylaxis

Dr. Canavan warns that wheat allergies tend to be more common in children, and symptoms typically appear within an hour of consuming wheat products.

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No matter the symptoms, leave the diagnosis to the professionals.

If you spend dinner with the in-laws nibbling on raw vegetables to avoid a potentially embarrassing trip to the bathroom, you might be tempted to start removing foods from your diet. But before you self-diagnose or swear off gluten for good, check in with an expert.

“We see this all the time. Patients come in and tell us they’ve already removed gluten from their diet, so they know it’s not celiac disease. But the only accurate way to diagnose – or rule out – celiac disease is with bloodwork and further testing like endoscopy and small bowel biopsy. Once you stop consuming gluten, it becomes much harder to accurately test,” says Dr. Canavan.

And a celiac diagnosis isn’t only important for you as a patient – it could be important for your family, too.

“If you are found to have celiac disease, your parents, children, and siblings need to be tested as well.”