A third of older adults in England are concurrently using herbal medicinal products (HMPs) and dietary supplements with prescription medicines and a third of these could be at risk for drug interactions, a new research published in the British Journal of General Practice suggests.
The cross-sectional survey used self-administered questionnaires to establish the prevalence of concurrent use of prescription drugs, HMPs and dietary supplements among 155 community-dwelling older adults registered at 2 general practices in South East England.
The prevalence of concurrent use of HMPs and dietary supplements with prescription medications was 33.6%. Prevalence was higher among women than men (43.4% vs 22.5%; P=.009).
The number of HMPs and dietary supplements being used by individual patients ranged from 1 to 8, with a mean of 3. The most commonly used dietary supplements were cod liver oil, glucosamine, multivitamins and vitamin D. Commonly used HMPs were evening primrose oil, valerian and Nytol Herbal (a combination of hops, gentian and passion flower).
Almost a third of participants (n=16) were found to be at risk for potential adverse herb-drug or supplement-drug interactions.
Just over half of the combinations (50.9%) were assessed as having ‘no interaction’ or ‘no interaction of clinical significance’. However, 21 combinations were categorised as interactions with ‘doubts about the outcome of concurrent use’. Three combinations were rated as ‘potentially hazardous’ and three as ‘significant hazard’.
HMPs with potential risk included flaxseed, evening primrose oil, St John’s wort, peppermint, senna, Echinacea, hawthorn, green tea and ginkgo. The dietary supplements with potential negative interactions were glucosamine, cod liver oil, omega 3 fish oil, calcium carbonate and multivitamins.
Potentially negative consequences included increased risk of bleeding with anticoagulants, increased serum glucose with metformin, and reduced levothyroxine efficacy.