Background: The use of herbal medicinal products (HMPs) is common among older adults; however, little is known about concurrent use with prescription drugs, as well as potential interactions associated with such combinations.

Objective: The aim of this systematic review was to identify and evaluate the literature on concurrent prescription and HMP use among older adults to assess prevalence, patterns, potential interactions and factors associated with this use.

Methods: Systematic searches were conducted in the MEDLINE, PsycINFO, EMBASE, CINAHL, AMED, Web of Science and Cochrane databases from inception to May 2017 for studies reporting concurrent use of prescription medicines with HMPs in adults ≥ 65 years of age. Quality was assessed using the Joanna Briggs Institute checklists. And the Evidence for Policy and Practice Information and Co-ordinating Centre (EPPI-Centre) three-stage approach to mixed method research was used to synthesise data.

Results: Twenty-two studies were included. A definition of HMPs or what was considered an HMP was frequently missing. Prevalence of concurrent use by older adults varied widely between 5.3 and 88.3%. Prescription medicines most combined with HMPs were antihypertensive drugs, β-blockers, diuretics, antihyperlipidemic agents, anticoagulants, analgesics, antihistamines, antidiabetics, antidepressants and statins. The HMPs most frequently used were Ginkgo biloba, garlic, ginseng, St John's wort, Echinacea, saw palmetto, evening primrose oil and ginger. Potential risks of bleeding due to the use of Ginkgo biloba, garlic or ginseng with aspirin or warfarin was the most reported herb-drug interaction. Some data suggest being female, and having a lower household income and less than a high-school education were associated with concurrent use.

Conclusion: The prevalence of concurrent prescription drugs and HMP use among older adults is substantial and potential interactions have been reported. Knowledge of the extent and manner in which older adults combine prescription drugs will aid healthcare professionals in appropriately identifying and managing patients at risk. Systematic Review Registration Number: PROSPERO 2014:CRD42014009091.