In the European Crohn's and Colitis Organisation (ECCO) paper of 2006 (Gut 2006;55(Suppl 1):i1–15), consensus on the diagnosis of Crohn’s disease was described. However, we were surprised that nothing was mentioned about the association between the use of mycophenolate mofetil (MMF, Cellcept) and the occurrence of Crohn’s-like enterocolitis.

MMF is widely used to prevent rejection after solid organ transplantation. The active compound, mycophenolic acid (MPA), is a reversible, non-competitive inhibitor of inosine monophosphate dehydrogenase (IMPDH), the rate-limiting enzyme in de novo purine biosynthesis in T and B lymphocytes. The most common adverse drug reactions of MMF are gastro-intestinal complaints.1^–3 In 2003, a prospective cohort study including 26 renal transplant recipients with persistent diarrhoea showed for the first time that in patients using MMF, Crohn’s-like enterocolitis could …