When Abdominal Pain Is Actually a Food Allergy: A GI Workup

At the 2026 Eastern Allergy Conference (EAC) in Palm Beach, Florida, Brian Lacy, MD, PhD, a gastroenterologist at Mayo Clinic, discussed the diagnostic challenges surrounding non-IgE-mediated food hypersensitivity, including adult-onset food protein-induced enterocolitis syndrome (FPIES) presenting as recurrent abdominal episodes.

Lacy acknowledged that these conditions remain underrecognized in gastroenterology. While meal-related abdominal symptoms are common, most gastroenterologists prioritize the more prevalent diagnoses—ulcers, vascular disorders, and structural abnormalities—before considering food hypersensitivity.

When a patient predictably reports meal-triggered symptoms with no clear structural cause, Lacy said clinicians should begin thinking about food allergies, both IgE and non-IgE mediated. He noted that more often than not, the patient will ultimately be referred to an allergist, who is best positioned to make this less common diagnosis.

When building a workup for unexplained recurrent abdominal symptoms, Lacy outlined a stepwise approach beginning with a thorough history—characterizing symptom type, frequency, previous treatments, and prior testing. Physical examination also plays a key role, including evaluation for the Carnett sign, which can distinguish abdominal wall nerve entrapment from true gastrointestinal pathology.

Initial laboratory testing typically includes a CBC, erythrocyte sedimentation rate, lipase, and liver chemistries. A plain abdominal x-ray is often ordered next, followed by gastroenterology referral if symptoms persist. Endoscopic evaluation, such as upper endoscopy and colonoscopy, along with cross-sectional imaging via CT are standard components of the workup at that stage.

Lacy said that only when this initial evaluation returns unremarkable results should clinicians turn their attention to allergic etiologies. At that point, testing for mucosal mast cells and eosinophils, along with serum tryptase levels, becomes appropriate—or referral to an allergist for further evaluation.

In the first part of the interview, Lacy discussed several allergic conditions that could present with episodic abdominal symptoms: hereditary angioedema (HAE), mast cell activation syndrome (MCAS), and eosinophilic GI disorders.

HAE is often the last condition a clinician thinks to check for given its rarity. Abdominal HAE attacks tend to present as discrete episodes separated by symptom-free intervals, with significant bloating and distension and, crucially, dilated intestinal loops on imaging.

MCAS can be identified by episodic symptom patterns and multi-organ involvement as the primary clinical filters—daily abdominal pain or bloating makes MCAS an unlikely diagnosis. Eosinophilic GI disorders require diagnosis through multiple biopsies across GI segments.

His key takeaway for attendees: resist diagnostic tunnel vision. Not all recurrent abdominal pain stems from ulcers, reflux, or gastritis. When standard therapies fail, allergic conditions deserve serious consideration.

“Keep your blinders off,” Lacy said. “All abdominal pain is not due to an ulcer or gastritis or reflux disease. Think outside the box. When somebody is not responding to what you think is good empiric therapy, think about some allergic condition. Although they’re not as common as many of the other things we deal with, they are out there, and we would feel badly if something was missed.”

Part 1 of the interview with Lacy can be watched here: Abdominal Pain and Bloating: When to Consider HAE, MCAS, and EGIDs

Editor’s note: Relevant disclosures for Lacy include Ardelyx, Salix Pharmaceuticals, and IRONWOOD PHARMACEUTICALS.

References

1. Lacy B. Evaluation and Management of Intermittent Abdominal Pain and Bloating. Poster presented at the Eastern Allergy Conference (EAC) in Palm Beach, Florida, on May 29.

2. Lacy B. Abdominal Pain and Bloating: When to Consider HAE, MCAS, and EGIDs. HCPLive. Published on June 15, 2026. Accessed June 16, 2026. https://www.hcplive.com/view/intermittent-abdominal-pain-bloating-hae-mcas-egid-evaluation