Lifestyle

5 Signs of Celiac Disease Most People Mistake for IBS

By Erica Coleman · August 12, 2026

You’ve been told you have IBS. You changed your diet, took the medication, and nothing got better. The reason might be that you have the wrong diagnosis.

An estimated 3 million Americans have celiac disease — a serious autoimmune condition triggered by gluten — and roughly 80% of them are undiagnosed. The average time from symptom onset to correct diagnosis is 6 to 10 years. The primary reason for the delay: the symptoms look almost identical to irritable bowel syndrome, which is what most patients are told they have first.

Your bloating and cramping don’t respond to IBS treatment. IBS and celiac disease both cause bloating, gas, abdominal cramping, and alternating diarrhea and constipation. The critical difference is that IBS treatments — low-FODMAP diets, fiber supplements, antispasmodics — should produce at least partial improvement within weeks. If you’ve followed an IBS protocol faithfully and your symptoms haven’t changed, the underlying cause may be autoimmune, not functional.

You’re tired in a way that doesn’t match your sleep. Celiac disease damages the lining of the small intestine, impairing the absorption of iron, folate, and vitamin B12 — all of which are essential for energy production. The resulting fatigue is persistent and disproportionate, similar to what people with iron deficiency or anemia experience. IBS causes fatigue too, but it’s typically related to disrupted sleep from discomfort, not from malabsorption.

You have an unexplained skin rash — especially on your elbows, knees, or buttocks. Dermatitis herpetiformis is an intensely itchy, blistering rash that appears almost exclusively in people with celiac disease. It’s considered so specific to celiac that its presence alone can confirm the diagnosis without an intestinal biopsy. Most patients with the rash have been treated for eczema, psoriasis, or allergic reactions for years before anyone connects it to gluten.

You’re losing weight or can’t gain it despite eating normally. Malabsorption from intestinal damage means your body isn’t extracting the full nutritional value of what you eat. Unexplained weight loss — or an inability to gain weight despite adequate calorie intake — is a hallmark of celiac disease that doesn’t typically occur with IBS.

Your dental enamel is damaged or you have recurrent mouth ulcers. Celiac disease can cause enamel defects, discoloration, and pitting on permanent teeth — damage that occurred during tooth development and is irreversible. Recurrent canker sores are also significantly more common in people with undiagnosed celiac disease. Dentists are sometimes the first providers to notice these patterns, though they rarely order the follow-up blood work themselves.

The diagnostic test is a simple blood panel — the tTG-IgA antibody test — followed by an intestinal biopsy if the blood work is positive. The critical requirement: you must be eating gluten when tested. Many patients who go gluten-free on their own before testing get false negatives, which delays the correct diagnosis further. If you suspect celiac, don’t eliminate gluten until after the test.