A polyantiseptic antimicrobial pharmaceutical composition for oral use, for the hygiene and treatment of oral diseases of bacterial, mycotic or viral etiology, for over-the-counter sale, without contraindications. The composition does not contain phenolic or, chlorophenolic compounds, and consists of a mixture of hydrogen peroxide, eugenol, natural camphor, zinc sulphate, sodium fluoride, xylitol, cetylpyridinium chloride and excipients. The formulation is used to deodorise, disinfect, astringe and soothe inflammation of the oral area, avoids the neoformation of bacterial plaque, prevents tooth cavities, inhibits the formation of dental tartar, improves the resistance of teeth to cavities, and treats and prevents oral aphthous ulcers.