Main Article Content

SN Sim
MAH Levine


natural health products, St. John’s wort, drug interactions, cyclosporine



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.



This study was conducted to evaluate pharmacists and natural health product retailers' knowledge on this topic.



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.



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.



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.

Abstract 183 | PDF Downloads 106


1. Natural Health Products Directorate. (2005). Baseline natural health products survey among consumers: Final report. Retrieved February 9, 2009, from http://www.hcsc. pubs/natur/eng_cons_survey-eng.php
2. Health Canada. (2007). Drugs and Health Products. Retrieved February 9, 2009, from Health Canada: prodnatur/index-eng.php
3. Canada NDMAC. (2005). Self-care: Making Canadians healthier. Retrieved February 9, 2009, from main.dspFile&FileID=108
4. Rickert K, Martinez RR, Martinez TT. Pharmacist knowledge of common herbal preparations. Proceedings of the Western Pharmacology Society 1999;42:1-2.
5. Johnson TB. Canadian pharmacy students' knowledge of herbal medicine. American Journal of Pharmaceutical Education 2008;72(4):75-84.
6. Dolder CL. Pharmacists' use of and attitudes and beliefs about alternative medications. American Journal of Health-System Pharmacy 2003;60(13):1352-7.
7. Clauson KA, McQueen CE, Shield KM, Bryant PJ. Knowledge and attitudes of pharmacists in Missouri regarding natural products. American Journal of Pharmaceutical Educucation 2003;67(2): Article 41.
8. Farrell J, Ries NM, Boon H. Pharmacists and natural health products: A systematic analysis of professional responsibilites in Canada. Pharmacy Practice 2008;6(1):33-42.
9. Chang ZK. Pharmacists' knowledge and attitudes toward herbal medicine. The Annals of Pharmacotherapy 2000;34:710-5.
10. Welna EM, Hadsall RS, Schommer JC. Pharmacists’ personal use, professional practice behaviours, and perceptions regarding herbal and other natural products. Journal of the American Pharmicists Association 2001;43(5):602-11.
11. Bupendra S, Walter S, Usha M, Sonalee S. Pharmacy student perspectives on classroom education about herbal supplements. American Journal of Pharmaceutical Education 2005;69(5):Article 102.
12. Dvorkin L, Gardiner P, Welan JS. Herbal medicine course within pharmacy curriculum. Journal of Herbal Pharmacotherapy 2004;4:47-58.
13. Bent S. Herbal medicine in the United States: Review of efficacy, safety, and regulation. The Journal of General Internal Medicine 2008;23(6):854-9.
14. De Smet, PAGM. Herbal remedies. The New England Journal of Medicine 2002;347:2046- 56.
15. Mills E, Montori VM, Wu P, Gallicano K, Clarke M, Guyatt G. Interaction of St. John’s wort with conventional drugs: Sytematic review of clinical trials. British Medical Journal 2004;329:27-30.
16. Hu Z, Yang X, Ho PCL, et al. Herb-drug interactions: A literature review. Drugs 2005;65(9):1239-82.
17. Fugh-Berman A Ernst E. Herb-drug interactions: Review and assessment of report reliablity. Journal of Clinical Pharmacology 2001;52:587-95.
18. Bilia AR, Gallori S, Vincieri FF. St. John’s wort and depression: efficacy, safety and tolerability-an update. Life Sciences 2002;70(26):3077-96.
19. Brazier NC, Levine MAH. An evaluation of the quality of herbal product information provided by health food store retailers and pharmacists in a Canadian city. Canadian Journal of Clinical Pharmacology 2002;9:108- 9.
20. GraphPad Software [Web software]. (2005). Retrieved February 17, 2009, from erval1.cfm
21. Ruschitzka F, Meier PJ, Turina M, Lüscher TF, Noll G. Acute heart transplant rejection due to Saint John’s wort. The Lancet 2000;355:548-9.
22. Markowitz JS, Donovan JL, DeVane CL, et al. Effect of St John’s wort on drug metabolism by induction of cytochrome P450 3A4 enzyme. Journal of American Medical Association 2003;290(11): 15004.
23. Henderson L, Yue QY, Bergquist C, Gerden B, Arlett P. St John's wort (Hypericum perforatum): drug interactions and clinical outcomes. Br J Clin Pharmacol. 2002;54:349- 56.