Antihistamines in the Treatment of Irritable Bowel Syndrome With Diarrhea

We have published a series of 5 patients with chronic post prandial diarrhea (PPD) that begins within 3 hours after eating, associated with dermatographia, responsive to antihistamines [2]. In these cases, no underlying causes were identified to explain PPD; diagnoses of food allergy, lactose intolerance, celiac disease, dumping syndromes, inflammatory bowel disease, systemic mastocytosis were excluded. Patients with the syndrome have prior histories of chronic urticaria and experience associated transient symptoms of flushing, headache, tachycardia, and abdominal bloating during PPD episodes.

This syndrome, except for our published report, have not been previously described in the medical literature. Patients with systemic mastocytosis and mast cell activation syndrome experience PPD but along with anaphylactic manifestations (e.g. wheezing, hypotension) and measurable mast cell biomarkers are identifiable in affected patients (i.e. serum mast cell tryptase or 24 hour urine methylhistamine, PGF2a). Therefore, it is important to characterize PPD responsive to antihistamines in a general GI patient population and to publish our findings. The impact on human health will be substantial; we found that these patients are undiagnosed and untreated for many years.

Our aim is to recruit a minimum of 29 (with a maximum of 50) patients from community (third-party) and the UC Health affiliated primary care, allergy and/or gastroenterology clinics and the Bernstein Allergy Group David Bernstein MD, a faculty member in the Division of Immunology, Rheumatology, and Allergy, Yashu Dhamija MD (faculty), allergy fellows and GI fellows will direct and implement subject screening and consenting

Inclusion criteria

• Age 18 years and older
• Prior to Diagnosis of IBS + diarrhea based on ICD 10 codes with or without constipation unresponsive to prior treatments
• Moderate to severe symptom severity score (>175 points) based on IBS symptom severity scale
• Seeking evaluation by a health care professional
• Negative serologic celiac panel
• No response to lactose elimination diet by history
• Normal colonoscopy
• Able to complete symptoms diaries and global evaluations

Exclusion criteria

• Confirmed IgE dependent food allergy as a cause of the gastrointestinal symptoms.
• Lactose intolerance by history
• Celiac disease by serology
• Inflammatory bowel disease or colitis
• Bile acid diarrhea by history
• Post-surgical GI symptoms (e.g., dumping syndrome) by history
• No colonoscopy performed
• GI malabsorption
• Current pregnancy
• Current severe depression or history of psychosis
• Current treatment with tricyclic antidepressants