Methods of treating adverse intestinal effects of a non-steroidal anti-inflammatory drugs (NSAID) in a subject by administering to the subject a therapeutically effective amount of a selective bacterial beta-glucuronidase inhibitor. The adverse intestinal effects to be treated include the formation or growth of an intestinal ulcer, increased intestinal permeability, the loss of intestinal villi, bleeding of the intestinal mucosa, and an increased intestinal inflammatory response. The methods are useful for treating the adverse effects of any NSAID such as propionic acid derivatives, carboxylic acid derivatives, enolic acid derivatives, fenamic acid derivatives, sulphonanilidies, and selective COX-2 inhibitors. The bacterial beta-glucuronidase inhibitors are selective for the inhibition of bacterial beta-glucuronidase enzymes and do not inhibit mammalian beta-glucuronidase.
