The results of the study of oral fluid in older persons with somatic pathology, which was followed for 1 month, are presented. The acid-base state of the oral fluid was evaluated, and the viscosity of the oral fluid was determined. According to the results of the study of oral fluid and its correction by means of hygiene in older persons with somatic diseases, the dynamics of the indicators of the acid-base state of the oral fluid, its shift to the alkaline side and the positive dynamics of the effect of the viscosity of the oral fluid were noted. To ensure that the risk of adverse effects from changes in the state of the oral fluid is reduced, a joint approach involving all health professionals is needed, taking into account the determinants of health and ensuring the development of effective methods for the prevention of dental diseases in older persons.