The aim of the study is to review the literature data on the effect of opioids on different experimental gastrointestinal mucosal lesions. The effect of morphine on the gastric mucosa is analysed. Gastric mucosal lesions are classified in different ways. Different ulcer models are discussed. A hypothesis that opioids aggravate the mucosal damage during stress is presented. The findings of this study are contradictory. Both inhibition and aggravation of mucosal lesions are reported. Such factors as dose of drug, rout and time of administration, sex are suspected to be responsible for these contradictory results.

Keywords: opioids, Gastrointestinal tract, mucosal lesions