Hay fever medicine reduces symptoms of irritable bowel syndrome

Researchers from KU Leuven, Belgium, have identified the cause of abdominal pain in patients with irritable bowel syndrome (IBS). As a result, they were able to select a medicine that could reduce or end that pain. This medicine is already used to treat hay fever.

IBS patients have extremely sensitive bowels associated with increased pain perception. This phenomenon is comparable to the increased sensitivity of our skin to hot water after sunburn. The exact cause of this hypersensitivity has long been unknown. Researchers already knew that the bowels of patients with IBS contain larger quantities of the substance histamine, but the specific link with hypersensitivity had not yet been made.

KU Leuven professor of gastroenterology Guy Boeckxstaens and his team have now shown that histamine has an impact on the pain receptor TRPV1. In IBS patients, histamine released in the gut makes TRPV1 hypersensitive. The researchers found that histamine interferes with the histamine 1 receptor, which is located on nerves that contain TRPV1. Importantly, they discovered that blocking the histamine 1 receptor prevented the sensitising effect of histamine on TRPV1. Taken together, these findings identify the mechanism behind IBS patients' increased pain perception.

On the basis of these findings, the researchers set out to find a solution to the problem. They designed a pilot clinical study in IBS to evaluate the effect of a substance that blocks the histamine 1 receptor on the nerves, so that the sensitivity of TRPV1 no longer increases. This substance, ebastine, is already used in hay fever medication. Patients who were treated with ebastine for 12 weeks had significantly less abdominal pain than patients from the control group. A follow-up study will test the effect of ebastine on 200 IBS patients.

Irritable bowel syndrome is a condition that affects 10-15% of the population. Treatment is currently limited to normalising the defecation pattern. It cannot reduce or end the abdominal pain experienced by IBS patients. The results of this study may help change that.