The invention relates to a pharmaceutical composition comprising lysozyme, dextranase and an essential oil of a plant belonging to the family Myrtaceae. The composition is preferably formulated, together with other ingredients, as a mouthwash.The invention also relates to a method for the prevention, treatment and follow-up of pathologies of the oral cavity of infectious, inflammatory, degenerative or autoimmune origin, the method comprising the administration of the composition of the invention to a patient affected by one or more of such pathologies, which are preferably selected in the group consisting of: gingivitis, periodontitis, aphthous stomatitis, herpetic stomatitis, prosthetic stomatitis, recurrent aphthosis, xerostomia, xerostomia due to Sjogren's syndrome, burning mouth syndrome (BMS), oral candidiasis, inflammatory dermatoses such as oral lichen planus, autoimmune disorders of the mucous membranes such as mucous membrane pemphigoid (MMP), graft-versus-host disease, white tongue, migratory glossitis, desquamative gingivitis due to oral lichen planus, herpes and combinations thereof.