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Use of herbal remedies and potential drug interactions in rheumatology outpatients
  1. W Holden1,
  2. J Joseph2,
  3. L Williamson3
  1. 1Nuffield Orthopaedic Centre, Windmill Road, Headington, Oxford, UK
  2. 2Nicosia Polyclinic, Nicosia, Cyprus
  3. 3Great Western Hospital, Swindon, UK
  1. Correspondence to:
    Dr W Holden
    wendy.holdennoc.anglox.nhs.uk

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Although the use of complementary and alternative therapies by rheumatology outpatients is increasingly acknowledged,1 little attention has been given to the safety of these treatments. Herbal and over the counter remedies are currently exempt from legislation governing conventional drugs such as quality control and post-marketing surveillance. The European Parliament has approved a directive proposed by the European Commission on traditional herbal medicines.2 Once this directive comes into force, legislation in the UK will follow and may lead to a registration scheme for traditional herbal remedies. It has been suggested that transitional licensing agreements will take at least 5½ years to establish.3 Until that time, it is probable that there will be an increase in the thousands of reports of adverse effects associated with herbal remedies,4 as well as more evidence of harmful interactions with conventional drugs. Rheumatology outpatients may be at particularly high risk of interactions with conventional medication because of high rates of polypharmacy and comorbidity.

Gingko biloba, devil’s claw, ginger, and garlic may have antiplatelet or other anticoagulant effects,5–8 and have been associated with haemorrhagic complications.9 These remedies may therefore exacerbate the gastrointestinal bleeding risk of non-steroidal anti-inflammatory drugs (NSAIDS) or corticosteroids. Echinacea may be hepatotoxic8 and exacerbate this adverse effect of disease modifying antirheumatic drugs (DMARDS).

Our aim was to quantify the proportion of rheumatology outpatients who were taking herbal or over the counter remedies and to assess the number at potential risk of harmful interactions with their conventional rheumatological drugs. We also looked at the patients’ perceived risk of the remedies they used and whether or not they had sought advice from a healthcare professional before starting the remedy.

Two hundred and thirty eight follow up rheumatology outpatients in three centres (Oxford, Swindon, Cirencester) completed an anonymous questionnaire about their rheumatological diagnosis, conventional drug treatment, and use of herbal and over the counter remedies during the past 6 months. Patients were asked whether they were aware of any side effects from the remedies, interactions with their prescription drug, and whether they had sought advice from a doctor or pharmacist before starting the remedy.

One hundred and five (44%) patients had used herbal or over the counter remedies in the past 6 months. The most commonly used remedies were cod liver oil (83/238 (35%)), glucosamine and/or chondroitin (50/238 (21%)), and evening primrose oil (26/238 (11%)). Twenty six (11%) patients were taking remedies that might interact with conventional drugs. Five of 120 (4%) patients receiving DMARDS were at increased risk of hepatotoxicity by also taking echinacea. Twenty four of 238 (10%) patients were at increased risk of bleeding disorders by also taking ginkgo biloba, garlic, or devil’s claw with NSAIDS or corticosteroids. Twenty four of 26 patients at risk of harmful interactions were unaware of this, and 10/26 had sought advice from a health professional before starting the remedy.

Doctors may not recognise potential adverse effects associated with herbal remedies, and patients may be reluctant to report either the use of herbal remedies or adverse effects.1,10 Healthcare workers should remember to be particularly vigilant to ask about herbal remedies when taking a drug history. Both patients and prescribers need more education on the risks and potential interactions of these preparations.

REFERENCES

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