The incidence of potential interactions between dietary supplements and prescription medications in cancer patients at a Veterans Administration Hospital

Objective: The concurrent use of dietary supplements and prescription medications is common among patients with cancer. This study examines potential interactions between dietary supplements and prescription medications in a Veteran Hospital cancer population. Methods: Eligible patients seen at the Hematology/Oncology clinic at the Veterans Administration Medical Center in Cincinnati, OH, were administered a survey to determine their use of dietary supplements. Medication profiles were compiled from patients' medical charts and pharmacy records. It was also noted whether supplementation was previously documented. Potential interactions between dietary supplements and prescription medications were identified from a literature search of documented interactions. Several demographic factors, including age, race, marital status, education and income, were assessed for differences between patients found to be at risk for interactions and those for whom no risks were identified. Results: Dietary supplements were used by 61% of patients. Multivitamins were the most common supplement (80.3%) followed by minerals (40.6%) and herbal preparations (24.8%). Of the 121 patients taking supplements, 65 patients (54%) reported taking more than one. A potential risk for interaction between dietary supplement and prescription medication was identified in 12% of patients taking supplementations. Three patients were at risk for multiple interactions. Veterans who were not currently married were more likely to be at risk for interactions (P = 0.024). Only 28% of patients taking dietary supplements had this supplementation documented in their medical record. Conclusion: Dietary supplementation by a veteran cancer population is common. Interactions between the supplement and prescription medication is a potential problem. Patient-physician discussion and documentation of these issues should be systematically addressed.