Intestinal microbiota is composed by a community of microorganisms, which regulate intestinal functions and
affect the global health. It is presumable that the well-known intestinal damages induced by Non Steroidal Antiinflammatory
Drugs (NSAIDs) mirror on the homeostasis of microbiota, as confirmed by studies investigating this aspect.
This review reports the evolving knowledge in this field taking into account both intestinal damage and microbiota
involvement. In addition, we analyze a recent study reporting how NSAIDs change intestinal bacterial composition and,
on this basis, hypothesize further possible interactions. Indeed, NSAIDs are responsible for a marked reduction of
Lactobacilli, which act in the maintenance of luminal pH, mucosal permeability, enterocyte adhesion, mucus production,
and immune system modulation. Moreover, Bifidobacteria are involved in the modulation of intestinal motility and local
immunity and the demonstrated dangerous effect of NSAIDs could operate through an interference with these functions.
A participation of microbiota in mesalazine and salycilate prevention of intestinal cancer may be supposed through their
ability to stimulate bacterial production of molecules interfering with cell cycle on the basis of scanty available data.
Finally, a supplementation with probiotics in chronic users of NSAIDs may help microbiota remodeling in a damaged
intestine, but the poor current knowledge does not allow setting a clear indication for their use despite few evidences of a
beneficial effect. In conclusion, it is presumable that the multiple effects of NSAIDs on the lower gastro-intestinal tract
may involve microbiota alterations and this consideration suggests further investigations.