Disclosed herein are complexes comprising rifaximin and a complexing agent, wherein the complexing agent is a polyvinyl pyrrolidone (PVP), preferably having a K-value ranging from K-15 to K-90, specifically K-30； or a cyclodextrin, preferably selected from ?-cyclodextrin, ?-cyclodextrin or ?-cyclodextrin； with the proviso that the complexing agent is not hydroxybutenyl cyclodextrin or a derivative thereof. Said complexes are useful in the treatment of bowel related disorders such as irritable bowel syndrome, diarrhoea, traveller's diarrhoea, microbe associated diarrhoea, Crohn's disease, chronic pancreatitis, pancreatic insufficiency and/or colitis.
