Exploring Beverage Intake and Dietary Timing Patterns in Medication-Induced Xerostomia: A Cross-Sectional Pilot Study

Background: Xerostomia, or the subjective sensation of dry mouth, is a prevalent side effect of medications. While its impact on oral function is well documented, limited research has examined how xerostomia influences beverage consumption and the timing of food intake, especially in non-cancer, middle-aged populations. Objectives: To examine associations between beverage intake, meal timing, and subjective and objective measures of salivary gland function in individuals with medication-induced xerostomia. Methods: This cross-sectional pilot study included 90 adults aged 45–66 taking anticholinergic medications. Salivary function was assessed via unstimulated whole saliva (UWS), minor salivary flow (MSF), and the Xerostomia Inventory (XI). Validated questionnaires evaluated habitual water and beverage intake, and meal timing. Multivariable models were adjusted for demographics, medication use, and comorbidities. Results: Hyposalivation (UWS ≤ 0.3 mL/min) was associated with higher XI scores (p = 0.033) and greater anticholinergic medication burden (p = 0.024). The later timing of last intake and last snack was independently associated with greater xerostomia severity. Total beverage and water intake were not associated with salivary flow or XI scores. Nighttime eating was correlated with higher anticholinergic burden. Conclusions: The timing of intake, rather than fluid volume, may better reflect symptom burden in medication-induced xerostomia, underscoring the behavioral adaptations to oral dryness.