Drug-induced xerostomia is common among elderly patients taking multiple medications. The condition significantly affects dental health and quality of life. This study aimed to evaluate the clinical and laboratory characteristics of oral fluid (OF) in xerostomia patients taking xerogenic medications, and to assess associations between total xerogenic load, salivary flow rates, and OF composition. The study included 60 people aged 45–75 years. The treatment group consisted of 40 patients with at least 3 months of dry mouth history and routine intake of two or more medications with known xerogenic potential. The control group included 20 healthy individuals exhibiting no signs of xerostomia and not taking medications routinely. We used the Xerostomia Inventory questionnaire to collect data from the participants; they also underwent clinical dental examination and sialometry for unstimulated and stimulated oral fluid (OF). The fluid samples were examined in the laboratory to determine pH, buffer capacity, total protein content, alpha-amylase activity, glucose and lactate levels. Compared to the control group, patients in the treatment group showed marked hyposalivation, decreased OF pH and buffer capacity, increased total protein content and alpha-amylase activity, and tended more often to have multiple caries lesions, candidal stomatitis, and atrophic changes in the oral mucosa. Thus, drug-induced xerostomia is accompanied by pronounced quantitative and qualitative changes in OF as well dental health and quality of life deterioration. A comprehensive clinical and laboratory assessment of OF provides an objective measure of xerostomia severity and enables compilation of tailored prevention and treatment programs.