Mucous membrane pemphigoid (MMP) is a heterogeneous group of autoimmune subepithelial blistering diseases affecting primarily mucous membranes showing marked degree of clinical and immunological variability. We investigated four controversial topics: (i) Does oral pemphigoid (OP) really exist as a separate entity? (ii) Is mucous membrane pemphigoid curable? (iii) What is the best therapeutic option for MMP? (iv) Does exclusive oral IgA dermatitis exist as a distinct entity from MMP? Results from extensive literature searches suggested that (i) it is still unclear whether patients with OP could be considered as a distinct subset of MMP with specific clinical and immunological features; (ii) it is uncertain whether treatment regimens that get MMP under control can be eliminated to allow patients to be in drug-free remission or they should be continuously administered in some capacities; (iii) there is a concerning paucity of good-quality trials on MMP and available recommendations are solely based on generally small patients' cohorts or case series. Some of the 2002 consensus experts' opinions should be possibly updated, particularly regarding the safety of sulfa drugs; (iv) we did not find any strong evidence to support an exclusive oral (and perhaps also mucosal) form of LAD as a separate entity.