Drugs & Aging

, Volume 26, Issue 5, pp 423–436 | Cite as

Prevalence of Polypharmacy, Polyherbacy, Nutritional Supplement Use and Potential Product Interactions among Older Adults Living on the United States-Mexico Border

A Descriptive, Questionnaire-Based Study
  • Amanda M. Loya
  • Armando González-Stuart
  • José O. Rivera
Original Research Article


Background and objective

The use of multiple medications, herbs or nutritional supplements can lead to adverse consequences, particularly in the elderly. A significant consequence resulting from polypharmacy, polyherbacy and nutritional supplement use is the potential for interactions to occur among the various products. The primary objective of this study was to estimate the prevalence of polypharmacy, polyherbacy, nutritional supplement use and potential product interactions among older adults living on the US-Mexico border.


This was a descriptive study that involved the administration of a bilingual (English/Spanish) questionnaire to a convenience sample of adults aged ≥60 years recruited from senior centres located within the most populated US-Mexico border region from June 2005 to March 2006. Participant demographics were collected in addition to information about current use of prescription medications, over-the-counter (OTC) medications, herbal products and nutritional supplements (i.e. nutraceuticals and vitamins or minerals). The outcomes measured were the number of prescription medications, OTC medications, herbal products, vitamins/minerals and nutraceuticals per participant. Furthermore, the number of potential interactions and major interactions between drugs, herbal products and nutritional supplements were identified for each participant. Additionally, product use patterns between men and women and among locations within the border region were compared.


One-hundred-and-thirty participants (mean age 71.4 years) were recruited to complete the questionnaire. The prevalence of polypharmacy among all participants was 72.3% (n = 94), with 38.5% (n = 50) taking five or more concomitant medications (major polypharmacy). Twenty-one participants (16.2%) in the study sample reported taking two or more herbal products (polyherbacy). Thirty-four participants (26.2%) reported taking two or more vitamin/mineral supplements and nine (6.9%) reported using two or more nutraceuticals. Participants living on the US side of the border had higher rates of major polypharmacy, polyherbacy and use of nutritional supplements than those living on the Mexican side of the border. Overall, there were no significant differences in medication, herbal product and nutritional supplement use patterns between men and women. Evaluation of potential interactions revealed that 46.2% (n = 60) of participants were at risk of having at least one potential drug-drug interaction. Regarding drug and herbal product-supplement interactions, 31.5% (n = 41) of participants were at risk of having at least one possible interaction.


The prevalence of polypharmacy among older adults living on the US side of the border was similar to national trends (estimates suggest that one-quarter to one-half of US adults aged ≥65 years take five or more medications). However, polypharmacy was less common in older adults living on the Mexican side of the border. Additionally, herb use was higher in older adults living on the US-Mexico border than has been reported in national surveys of US adults, which indicate that less than one-quarter of adults have used a herbal product within the previous 12 months. Furthermore, this study demonstrated that older adults living on the US side of the border consumed more herbs and nutritional supplements than their Mexican counterparts. In addition to describing product use patterns on the border, these findings suggest that almost half of the older adult participants were at risk for a potential drug-drug interaction, with approximately one-third having a potential interaction between their medications, herbs or nutritional supplements.


Nutritional Supplement Herbal Product Grape Seed Extract Senior Centre Thioctic Acid 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



This work was supported by a grant from the Paso del Norte Health Foundation, El Paso, Texas, USA. The funding organization did not participate in the design or conduct of the study, management, analysis or interpretation of the data, or preparation, review or approval of the manuscript. We thank Dr Melchor Ortiz for his assistance with the statistical analysis. The authors have no conflicts of interest that are directly relevant to the content of this study.


  1. 1.
    Fulton MM, Allen ER. Polypharmacy in the elderly: a literature review. J Am Acad Nurse Pract 2005 Apr; 17(4): 123–32PubMedCrossRefGoogle Scholar
  2. 2.
    Rolason V, Vogt N. Reduction of polypharmacy in the elderly. Drugs Aging 2003; 20(11): 817–32CrossRefGoogle Scholar
  3. 3.
    Safran DG, Neuman P, Schoen C, et al. Prescription drug coverage and seniors: findings from a 2003 national survey. Health Aff 2005 Apr; W5–152Google Scholar
  4. 4.
    Wilson I, Schoen C, Neuman P, et al. Patient-physician communication about prescription medication non-adherence: a 50 state study of America’s seniors. J Gen Intern Med 2007 Jan; 22(1): 6–12PubMedCrossRefGoogle Scholar
  5. 5.
    Veehof LJG, Stewart RE, Haaijer-Ruskamp FM, et al. The development of polypharmacy: a longitudinal study. Fam Pract 2000 Jun; 17(3): 261–7PubMedCrossRefGoogle Scholar
  6. 6.
    Ness J, Johnson D, Nisly N. “Polyherbacy”: herbal supplements as a form of polypharmacy in older adults. J Gerontol A Biol Sci Med Sci 2003 May; 58: M478PubMedCrossRefGoogle Scholar
  7. 7.
    Kaufman DW, Kelly JP, Rosenberg L, et al. Recent patterns of medication use in the ambulatory adult population of the United States: the Slone Survey. JAMA 2002 Jan 16; 287(3): 337–44PubMedCrossRefGoogle Scholar
  8. 8.
    Barnes PM, Powell-Griner E, McFann K, et al. Complementary and alternative medicine use among adults: United States, 2002. Adv Data 2004 May 27; 343: 1–19PubMedGoogle Scholar
  9. 9.
    Eisenberg DM, Davis RB, Ettner SL, et al. Trends in alternative medicine use in the United States, 1990–1997. JAMA 1998 Nov 11; 280(18): 1569–75PubMedCrossRefGoogle Scholar
  10. 10.
    Rock CL. Multivitamin-multimineral supplements: who uses them? Am J Clin Nutr 2007 Jan; 85(1): 277S–9SPubMedGoogle Scholar
  11. 11.
    Timbo BB, Ross MP, McCarthy PV, et al. Dietary supplements in a national survey: Prevalence of use and reports of adverse events. J Am Diet Assoc 2006 Dec; 106(12): 1966–74PubMedCrossRefGoogle Scholar
  12. 12.
    Radimer K, Bindewald B, Hughes J, et al. Dietary supplement use by US adults: data from the National Health and Nutrition Examination Survey, 1999–2000. Am J Epidemiol 2004 Aug 15; 160(4): 339–49PubMedCrossRefGoogle Scholar
  13. 13.
    Marinac JS, Buchinger CL, Godfrey LA, et al. Herbal products and dietary supplements: a survey of use, attitudes, and knowledge among older adults. J Am Osteopath Assoc 2007 Jan; 107(1): 13–20PubMedGoogle Scholar
  14. 14.
    Wold RS, Lopez ST, Yau CL, et al. Increasing trends in elderly persons’ use of nonvitamin, nonmineral dietary supplements and concurrent use of medications. J Am Diet Assoc 2005 Jan; 105(1): 54–63PubMedCrossRefGoogle Scholar
  15. 15.
    Kales HC, Blow FC, Welsh DE, et al. Herbal products and other supplements: use by elderly veterans with depression and dementia and their caregivers. J Geriatr Psychiatry Neurol 2004 Mar; 17(1): 25–31PubMedCrossRefGoogle Scholar
  16. 16.
    Astin JA, Pelletier KR, Marie A, et al. Complementary and alternative medicine use among elderly persons: one-year analysis of a Blue Shield Medicare supplement. J Gerontol A Biol Sci Med Sci 2000 Jan; 55(1): M4–9PubMedCrossRefGoogle Scholar
  17. 17.
    Rivera JO, Anaya JP, Meza A. Herbal product use in Mexican-Americans. Am J Health Syst Pharm 2003 Jun 15; 60(12): 1281–2PubMedGoogle Scholar
  18. 18.
    Rivera JO, Ortiz M, Gonzalez-Stuart A, et al. Bi-national evaluation of herbal product use on the United States/Mexico border. J Herb Pharmacother 2007; 7(3–4): 91–103PubMedGoogle Scholar
  19. 19.
    Gaddis GM, Holt TR, Woods M. Drug interactions in at-risk emergency department patients. Acad Emerg Med 2002 Nov; C9(11): 1162–7CrossRefGoogle Scholar
  20. 20.
    Goldberg RM, Mabee J, Chan L, et al. Drug-drug and drug-disease interactions in the ED: analysis of a high-risk population. Am J Emerg Med 1996 Sep; 14(5): 447–50PubMedCrossRefGoogle Scholar
  21. 21.
    Bush TM, Rayburn KS, Holloway SW, et al. Adverse interactions between herbal and dietary substances and prescription medications: a clinical survey. Altern Ther Health Med 2007 Mar–Apr; 13(2): 30–5PubMedGoogle Scholar
  22. 22.
    El Paso information and links: population [online]. Available from URL: [Accessed 2007 Nov 15]
  23. 23.
    Brandon JE. Border health: an overview of challenges along the U.S.-Mexico border [online]. Available from URL: [Accessed 2008 Sep 25]
  24. 24.
    Byrd TE, Law JA. Cross-border utilization of medical services on the U.S.-Mexico border (north to south) [abstract no. 179729]. 136th Annual Meeting and Expo, American Public Health Association; 2008 Oct 25–29; San Diego (CA)Google Scholar
  25. 25.
    Escobedo LG, Cardenas VM. Utilization and purchase of medical care services in Mexico by residents in the United States of America. Rev Panam Salud Publica 2006 Jun; 19(5): 300–5PubMedCrossRefGoogle Scholar
  26. 26.
    Rivera JO, Ortiz M, Cardenas VM. Cross-border purchase of medications and health care in a sample of residents of El Paso, Texas and Ciudad Juarez, Mexico. J Natl Med Assoc 2009; 101(2): 167–73PubMedGoogle Scholar
  27. 27.
    Census Bureau State and County quick facts. El Paso County, Texas [online]. Available from URL: [Accessed 2008 Jul 18]
  28. 28.
    Instituto Nacional de Estadística y Geografia (INEGI) [online]. Available from URL: [Accessed 2008 Jul 29]
  29. 29.
    Environmental Protection Agency. U.S. Mexico border 2012 program [online]. Available from URL: [Accessed 2008 Jul 18]
  30. 30.
    Census Bureau State and County quick facts. Alamogordo, New Mexico [online]. Available from URL: [Accessed 2008 Jul 18]
  31. 31.
    Alamogordo (NM). Distance calculator [online]. Available from URL: [Accessed 2008 Jul 11]
  32. 32.
    Jonas W, editor. Dictionary of complementary and alternative medicine. New York (NY): Elsevier-Mosby, 2005Google Scholar
  33. 33.
    Thomson Micromedex. DRUG-REAX® system [online]. Available from URL: [Accessed 2007 Aug 20]
  34. 34.
    Lexi-Interact™ [database]. v. 20051215. Hudson (OH): Lexi-Comp, Inc., 2007 Aug 20Google Scholar
  35. 35.
    Ulbricht C, Basch E, editors. Natural standard herb and supplement reference. New York (NY): Elsevier-Mosby, 2005Google Scholar
  36. 36.
    Brinker F. Herb and drug interactions. 3rd rev. ed. Sandy (OR): Eclectic Medical Publications, 2003Google Scholar
  37. 37.
    Department of Transportation, Bureau of Transportation Statistics. U.S. border crossings/entries: El Paso, Texas, 2007 [online]. Available from URL: [Accessed 2008 Sep 25]
  38. 38.
    Kay M. Healing with plants in the American and Mexican west. Tucson (AZ): University of Arizona Press, 2000Google Scholar
  39. 39.
    Davidow J. Infusions of healing: a treasury of Mexican-American herbal remedies. New York (NY): Fireside Books, 1999Google Scholar
  40. 40.
    Kelly JP, Kaufman DW, Kelley K, et al. Use of herbal/natural supplements according to racial/ethnic group. J Altern Complement Med 2006 Jul–Aug; 12(6): 555–61PubMedCrossRefGoogle Scholar
  41. 41.
    Dergal JM, Gold JL, Laxer DA, et al. Potential interactions between herbal medicines and conventional drug therapies used by older adults attending a memory clinic. Drugs Aging 2002; 19(11): 879–86PubMedCrossRefGoogle Scholar
  42. 42.
    Fick DM, Cooper JW, Wade WE, et al. Updating the Beers criteria for potentially inappropriate medication use in older adults. Arch Intern Med 2003 Dec; 163: 2716–24PubMedCrossRefGoogle Scholar

Copyright information

© Adis Data Information BV 2009

Authors and Affiliations

  • Amanda M. Loya
    • 1
    • 2
  • Armando González-Stuart
    • 1
  • José O. Rivera
    • 1
    • 2
  1. 1.The University of Texas at El Paso College of Health SciencesEl PasoUSA
  2. 2.The University of Texas at Austin College of PharmacyAustinUSA

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