An evaluation of pharmacist and health food store retailer's knowledge regarding potential drug interactions associated with St. John's wort.

BACKGROUND: Natural health products (NHP) are increasingly being used by patients concomitantly receiving prescription drugs, which can result in potentially serious drug-herb interactions. This is particularly true for St. John's wort. OBJECTIVE: This study was conducted to evaluate pharmacists and natural health product retailers' knowledge on this topic. METHODS: An interviewer approached 24 pharmacists and 6 natural health product retailers to obtain information regarding St. John's wort. If asked, the interviewer indicated that they were currently using cyclosporine to treat a problem of proteinuria. The response of the pharmacist or NHP retailer to a series of questions was recorded after the encounter. RESULTS: 90% of respondents indicated that St. John's wort was useful for treating depression. Two-thirds of the respondents required prompting by the interviewer before providing any comments pertaining to safety. 60% of the respondents inquired about concurrent medications and 40% made statements regarding potential drug-herb interactions. CONCLUSION: Despite the potential for a serious drug-herb interaction involving St. John's wort and cyclosporine, less than half of the pharmacists and natural health product retailers that were encountered in the study addressed this topic with the prospective patient/client. Individuals selling natural health products need to communicate more information to their patients/clients regarding potential drug-herb interactions.