Effect of seasonal exposure in aeroallergen-sensitized patients with irritable bowel syndrome-diarrhoea

Background. Pollen allergy may have an influence on irritable bowel syndrome (IBS) symptoms, but data are scant. Aims. To assess symptom variability in atopic IBS patients. Methods. We retrospectively analysed consecutive adult IBS patients evaluated in 2021-2024. Patients from the overall IBS cohort and the IBS-diarrhoea (IBS-D) subgroup were classified according to their sensitization into Grasses positive, House-dust mite (HDM) positive or unsensitised. Symptom burden was assessed with the gastrointestinal symptom rating scale (GSRS) and visual analogue scale (VAS) for abdominal pain/distension out of the season period (T0) and at the pollination season (T1). Results. Overall, 61 IBS (median age 34 years, IQR 25-50, F:M ratio 3.6:1) of whom 38 (62.8%) IBS-D (median age 30 years, IQR,28-47, F:M ratio 2.8:1) patients were recruited. Atopy was common in the IBS-D subgroup, particularly respiratory manifestations. The mean GSRS significantly (p<0.01) increased at T1 (variance of 3.4 points) only in Grass-sensitized patients as opposed to those sensitized to HDM or unsensitised ones and this effect was present only in the IBS-D subgroup, while in the overall cohort no significant variation was observed. Conclusions. Pollination season has an influence on symptoms in IBS-D patients sensitized to seasonal allergens.