International Journal of Clinical Pharmacy

, Volume 36, Issue 1, pp 92–97 | Cite as

Correlation between the use of ‘over-the-counter’ medicines and adherence in elderly patients on multiple medications

  • Charlotte OlesenEmail author
  • Philipp Harbig
  • Ishay Barat
  • Else Marie Damsgaard
Research Article


Background Medication adherence is a multifaceted issue that is influenced by various factors. One factor may be the concurrent use of over-the-counter (OTC) medicines. The use of OTC medicine has been reported as common amongst elderly patients. Objective To determine if a correlation exists between the use of OTC medicines and adherence to prescribed medications in elderly patients. Setting Non-institutionalised elderly patients in Denmark. Methods Elderly unassisted patients aged ≥65 prescribed five or more prescription drugs were included in the study. Information on the use of concurrent OTC medications (herbal medicines, dietary supplements, or non-prescribed drugs) was elicited during home visit interviews. Prescription drug adherence was determined by pill counts. A patient was categorised as non-adherent if the mean adherence rate for all drugs consumed was <80 %. Different sensitivity analyses were made where adherence was defined different. Main outcome measure Medication adherence based on pill-count. Results A total of 253 participants included 72 % who used OTC medicines and 11 % who did not adhere to their prescriptions. Users of OTC medicines, however, were significantly more likely to be adherent than were non-users (odds ratio 0.41; 95 % confidence interval 0.18–0.91). Sensitivity analyses where adherence was defined different show no relationship between adherence and use of OTC medicine. Furthermore, separate analyses of herbal medicines, dietary supplements, or non-prescribed drugs did not correlate with adherence to prescriptions. Conclusion Amongst elderly patients on multiple medications a positive relationship was found between the overall use of OTC medicines and adherence to prescription drugs, in contrast to none when adherence were defined different or herbal medicines, dietary supplements, or non-prescribed drugs were analysed separately.


Denmark Dietary supplement Elderly Herbal medicine Medicine adherence Non-prescription drugs Over-the-counter medicine Self-care Self-medication 



This study was supported by the Danish Ministry of Health and the Association of Danish Pharmacies.

Conflicts of interest

The authors declare no conflict of interests.


  1. 1.
    Banning M. Older people and adherence with medication: a review of the literature. Int J Nurs Stud. 2008;45(10):1550–61.PubMedCrossRefGoogle Scholar
  2. 2.
    Hughes CM. Medication non-adherence in the elderly: how big is the problem? Drugs Aging. 2004;21(12):793–811.PubMedCrossRefGoogle Scholar
  3. 3.
    Gonzalez-Stuart A. Herbal product use by older adults. Maturitas. 2011;68(1):52–5.PubMedCrossRefGoogle Scholar
  4. 4.
    Dergal JM, Gold JL, Laxer DA, Lee MSW, Binns MA, Lanctot KL, et al. Potential interactions between herbal medicines and conventional drug therapies used by older adults attending a memory clinic. Drugs Aging. 2002;19(11):879–86.PubMedCrossRefGoogle Scholar
  5. 5.
    Loya AM, Gonzalez-Stuart A, Rivera JO. 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. Drugs Aging. 2009;26(5):423–36.PubMedCrossRefGoogle Scholar
  6. 6.
    Ly J, Percy L, Dhanani S. Use of dietary supplements and their interactions with prescription drugs in the elderly. Am J Health Syst Pharm. 2002;59(18):1759–62.PubMedGoogle Scholar
  7. 7.
    Yoon SL, Schaffer SD. Herbal, prescribed, and over-the-counter drug use in older women: prevalence of drug interactions. Geriatr Nurs. 2006;27(2):118–29.PubMedCrossRefGoogle Scholar
  8. 8.
    MacLaughlin EJ, Raehl CL, Treadway AK, Sterling TL, Zoller DP, Bond CA. Assessing medication adherence in the elderly: which tools to use in clinical practice? Drugs Aging. 2005;22(3):231–55.PubMedCrossRefGoogle Scholar
  9. 9.
    Krousel-Wood M, Thomas S, Muntner P, Morisky D. Medication adherence: a key factor in achieving blood pressure control and good clinical outcomes in hypertensive patients. Curr Opin Cardiol. 2004;19(4):357–62.PubMedCrossRefGoogle Scholar
  10. 10.
    Ekwunife OI, Oreh C, Ubaka CM. Concurrent use of complementary and alternative medicine with antiretroviral therapy reduces adherence to HIV medications. Int J Pharm Pract. 2012;20(5):340–3.PubMedCrossRefGoogle Scholar
  11. 11.
    Owen-Smith A, Diclemente R, Wingood G. Complementary and alternative medicine use decreases adherence to HAART in HIV-positive women. AIDS Care. 2007;19(5):589–93.PubMedCrossRefGoogle Scholar
  12. 12.
    Jernewall N, Zea MC, Reisen CA, Poppen PJ. Complementary and alternative medicine and adherence to care among HIV-positive Latino gay and bisexual men. AIDS Care. 2005;17(5):601–9.PubMedCrossRefGoogle Scholar
  13. 13.
    Matthees BJ, Anantachoti P, Kreitzer MJ, Savik K, Hertz MI, Gross CR. Use of complementary therapies, adherence, and quality of life in lung transplant recipients. Heart Lung. 2001;30(4):258–68.PubMedCrossRefGoogle Scholar
  14. 14.
    Weizman AV, Ahn E, Thanabalan R, Leung W, Croitoru K, Silverberg MS, et al. Characterisation of complementary and alternative medicine use and its impact on medication adherence in inflammatory bowel disease. Aliment Pharmacol Ther. 2012;35(3):342–9.PubMedCrossRefGoogle Scholar
  15. 15.
    Gohar F, Greenfield SM, Beevers DG, Lip GY, Jolly K. Self-care and adherence to medication: a survey in the hypertension outpatient clinic. BMC Complement Altern Med. 2008;8:4.PubMedCentralPubMedCrossRefGoogle Scholar
  16. 16.
    Cherniack EP. Complementary medicine use is not associated with non-adherence to conventional medication in the elderly: a retrospective study. Complement Ther Clin Pract. 2011;17(4):206–8.PubMedCrossRefGoogle Scholar
  17. 17.
    Krousel-Wood MA, Muntner P, Joyce CJ, Islam T, Stanley E, Holt EW, et al. Adverse effects of complementary and alternative medicine on antihypertensive medication adherence: findings from the cohort study of medication adherence among older adults. J Am Geriatr Soc. 2010;58(1):54–61.PubMedCentralPubMedCrossRefGoogle Scholar
  18. 18.
    Harbig P. Methods for Improving Compliance with Medicine Intake (MICMI). 2012. Available at: Accessed Nov 2013.
  19. 19.
    Harbig P, Barat I, Lund Nielsen P, Damsgaard EM. Instantaneous detection of nonadherence: quality, strength, and weakness of an electronic prescription database. Pharmacoepidemiol Drug Saf. 2012;21(3):323–8.PubMedCrossRefGoogle Scholar
  20. 20.
    Halpern MT, Khan ZM, Schmier JK, Burnier M, Caro JJ, Cramer J, et al. Recommendations for evaluating compliance and persistence with hypertension therapy using retrospective data. Hypertension. 2006;47(6):1039–48.PubMedCrossRefGoogle Scholar
  21. 21.
    Olesen C, Harbig P, Barat I, Damsgaard EM. Absence of ‘over-the-counter’ medicinal products in on-line prescription records: a risk factor of overlooking interactions in the elderly. Pharmacoepidemiol Drug Saf. 2013;22(2):145–50.PubMedCrossRefGoogle Scholar
  22. 22.
    Vik SA, Maxwell CJ, Hogan DB. Measurement, correlates, and health outcomes of medication adherence among seniors. Ann Pharmacother. 2004;38(2):303–12.PubMedCrossRefGoogle Scholar
  23. 23.
    Barat I, Andreasen F, Damsgaard EMS. The consumption of drugs by 75-year-old individuals living their own homes. Eur J Clin Pharmacol. 2000;56(6–7):501–9.PubMedCrossRefGoogle Scholar
  24. 24.
    Stjernberg L, Berglund J, Halling A. Age and gender effect on the use of herbal medicine products and food supplements among the elderly. Scand J Prim Health Care. 2006;24(1):50–5.PubMedCrossRefGoogle Scholar
  25. 25.
    Raji MA, Kuo YF, Al Snih S, Sharaf BM, Loera JA. Ethnic differences in herb and vitamin/mineral use in the elderly. Ann Pharmacother. 2005;39(6):1019–23.PubMedCrossRefGoogle Scholar
  26. 26.
    Brownie S. Predictors of dietary and health supplement use in older Australians. Aust J Adv Nurs. 2006;23(3):26–32.PubMedGoogle Scholar
  27. 27.
    Osterberg L, Blaschke T. Adherence to medication. N Engl J Med. 2005;353(5):487–97.PubMedCrossRefGoogle Scholar
  28. 28.
    Coleman CI, Limone B, Sobieraj DM, Lee S, Roberts MS, Kaur R, et al. Dosing frequency and medication adherence in chronic disease. J Manag Care Pharm. 2012;18(7):527–39.PubMedGoogle Scholar

Copyright information

© Koninklijke Nederlandse Maatschappij ter bevordering der Pharmacie 2013

Authors and Affiliations

  • Charlotte Olesen
    • 1
    Email author
  • Philipp Harbig
    • 1
  • Ishay Barat
    • 2
  • Else Marie Damsgaard
    • 1
  1. 1.Department of GeriatricsAarhus University HospitalAarhus CDenmark
  2. 2.Department of Medicine/GeriatricsHorsens HospitalHorsensDenmark

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