Arthritis patients need more information on herb-drug interactions

A number of surveys have previously highlighted the lack of consideration given to potential herb-drug interactions. Rheumatology outpatients may be at particularly high risk of interactions with conventional drugs because they are likely to be taking several drugs at the same time and to have other ailments, say the authors of the new study.

The UK team anonymously surveyed 238 outpatients with arthritis from three clinics in the West of England. The patients were asked about their treatment and whether they had used any herbal or over the counter remedies within the past six months.

The participants were also asked whether they knew of any possible side effects of the remedies they were taking, interactions with their conventional treatment, and whether they had sought the advice of a healthcare professional before taking the remedy.

Forty-four per cent of patients had used a herbal or over the counter remedy within the preceding six months, according to the letter published in this month's issue of the Annals of the Rheumatic Diseases​ (vol64, p790).

Around a third had taken cod liver oil, and one in five had taken glucosamine and/or chondroitin. Around one in 10 had used evening primrose oil.

The survey was carried out prior to the revelation of health risks associated with arthritis drug Vioxx and other Cox-2 inhibitors. Use of natural remedies is expected to increase further following their withdrawal from the market. There are also growing concerns about the long-term safety of other prescription and over-the-counter pain relievers.

However the survey suggests that doctors need to be aware of this increased use of natural remedies. The researchers found that one in 10 of those surveyed were taking supplements that could interact with conventional drugs.

These included echinacea, which boosts the risk of liver toxicity when taken with arthritis drugs, and ginkgo biloba, garlic, and devil's claw, all of which increase the risk of bleeding disorders when taken with non-steroidal anti-inflammatory drugs or steroids.

Twenty four of the 26 patients who had put themselves at risk were unaware that they had done so, and 10 of them had sought advice from a healthcare professional before opting for complementary treatment.

"Doctors may not recognise the potential adverse effects associated with herbal remedies, and patients may be reluctant to report either the use of herbal remedies or adverse effects,"​ say the researchers.

Author Dr Wendy Holden from the Nuffield Orthopaedic Centre in Oxford told NutraIngredients.com: "The risks are similar for anyone taking anti-inflammatory drugs. Most people who have come off Vioxx have just been switched to another anti-inflammatory, although some have come off them altogether which reduces their risk of interactions."​

Both patients and prescribers need more information education on the risks and potential interactions of alternative remedies, claim the authors.