A regimen consisted on a combination of a calcineurin inhibitor (CNI) with a short course of methotrexate (MTX) is the most widely used regimen for the prevention of GVHD after allogeneic hematopoietic cell transplantation (alloHCT). While the CNI is given in an adjusted dose, based on blood levels, MTX is given at a fixed 3 or 4 doses (15 mg/m2 on day +1, 10 mg/m2 on days +3, +6 +/- day +11). However, its use may be associated with considerable toxicity, including delayed engraftment, hepatotoxicity, nephrotoxicity and particularly oral mucositis (OM). The basis for OM is integrated: conditioning regimen and MTX prophylaxis for acute GVHD. OM has been shown to be associated with increased mortality and morbidity (principally from infection), significant pain, dysgeusia, difficulty speaking, difficulty receiving nutrition, hydration and oral medications, prolonged hospitalization and increased costs of care.