• Sunita Vohra, Kosta Cvijovic, Heather Boon, Brian C Foster, Walter Jaeger, Don LeGatt, George Cembrowski, Mano Murty, Ross T Tsuyuki, Joanne Barnes, Theresa L Charrois, John T Arnason, Candace Necyk, Mark Ware, and Rhonda J Rosychuk.
• Complementary and Alternative Research Program (CARE) for Integrative Health and Healing, Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada. CARE@med.ualberta.ca
• Plos One. 2012 Jan 1; 7 (9): e45196.

BackgroundMany consumers use natural health products (NHPs) concurrently with prescription medications. As NHP-related harms are under-reported through passive surveillance, the safety of concurrent NHP-drug use remains unknown. To conduct active surveillance in participating community pharmacies to identify adverse events related to concurrent NHP-prescription drug use.Methodology/Principal FindingsParticipating pharmacists asked individuals collecting prescription medications about (i) concurrent NHP/drug use in the previous three months and (ii) experiences of adverse events. If an adverse event was identified and if the patient provided written consent, a research pharmacist conducted a guided telephone interview to gather additional information after obtaining additional verbal consent and documenting so within the interview form. Over a total of 112 pharmacy weeks, 2615 patients were screened, of which 1037 (39.7%; 95% CI: 37.8% to 41.5%) reported concurrent NHP and prescription medication use. A total of 77 patients reported a possible AE (2.94%; 95% CI: 2.4% to 3.7%), which represents 7.4% of those using NHPs and prescription medications concurrently (95%CI: 6.0% to 9.2%). Of 15 patients available for an interview, 4 (26.7%: 95% CI: 4.3% to 49.0%) reported an AE that was determined to be "probably" due to NHP use.Conclusions/SignificanceActive surveillance markedly improves identification and reporting of adverse events associated with concurrent NHP-drug use. Although not without challenges, active surveillance is feasible and can generate adverse event data of sufficient quality to allow for meaningful adjudication to assess potential harms.

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