Potential for Interactions Between Dietary Supplements and Prescription Medications

Purpose The objective of this study was to assess the frequency of clinically significant interactions caused by concurrent use of dietary supplements and prescription medication. Methods We conducted a cross-sectional, point-of-care survey and combined the findings with a review of patient medical records. Patients treated at Mayo Clinic (Rochester, Minn) in 6 different specialty clinics were surveyed for their use of dietary supplements. Concurrent use of prescription medications was obtained from patients’ medical records. We used the Lexi-Interact online medication and dietary supplement interaction analysis program to assess the potential clinical significance of each interaction. Results We surveyed 1818 patients; 1795 responded (overall response rate of 98.7%) and 710 (39.6%) reported use of dietary supplements. In total, 107 interactions with potential clinical significance were identified. The 5 most common natural products with a potential for interaction (garlic, valerian, kava, ginkgo, and St John’s wort) accounted for 68% of the potential clinically significant interactions. The 4 most common classes of prescription medications with a potential for interaction (antithrombotic medications, sedatives, antidepressant agents, and antidiabetic agents) accounted for 94% of the potential clinically significant interactions. No patient was harmed seriously from any interaction. Conclusions A small number of prescription medications and dietary supplements accounted for most of the interactions. The actual potential for harm was low.