A new paper that investigates the potentially harmful interactions between "natural" remedies and medications finds interactions are substantially underreported and current knowledge is still "woefully incomplete." The review appears in the latest issue of the International Journal of Clinical Practice.
"Consumer use of HDS [herbs and dietary supplements] has risen dramatically over the past two decades" says review co-author Dr Hsiang-Wen Lin, from the College of Pharmacy in Taiwan. "In the USA, for example, it is estimated that more than 50 per cent of patients with chronic diseases or cancer use them and that many patients take them at the same time as prescribed medication."
Lin's review analysed dozens of previous studies and found that the greatest problems were caused by interactions between prescribed drugs and supplements that included ingredients such as St John's Wort, magnesium, calcium, iron or ginkgo.
"Despite their widespread use, the potential risks associated with combining HDS with other medications, which include mild-to-severe heart problems, chest pain, abdominal pain and headache, are poorly understood," Lin reports.
Some of the review's other key findings included:
- Warfarin, insulin, aspirin and ticlopidine had the greatest number of reported interactions with herbs and dietary supplements.
- Around half of the drug interactions were caused by the herbs and dietary supplements altering the pharmacokinetics of the prescribed drugs (typically, how the drug is absorbed, distributed, metabolized and eliminated by the body).
- Flaxseed, Echinacea and yohimbe had the largest number of documented interactions.
According to Lin, herbal and botanical remedies are more likely to have drug interactions than other dietary supplements, such as vitamins, minerals and amino acids.
Commenting on the review, Professor Edzard Ernst, chair in complementary medicine at the University of Exeter, notes that large proportions of the population are trying "natural" remedies for illness-prevention and all sorts of ailments. "The potential for such interactions is substantial," he warns. "Despite this consensus and despite the considerable amount of documented harm generated by such interactions, our current knowledge is still woefully incomplete."
Ernst believes that the number of interactions between HDS and prescribed drugs could be under-reported and just the tip of the iceberg. Increased awareness of possible HDS interactions by physicians and patients is warranted, he added, along with greater government control of the supplement industry. "We have to become vigilant and finally agree to monitor this sector adequately. Each individual doctor can contribute to this process by routinely including questions about alternative medicine use in their medical history taking," he concluded.
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Source: International Journal of Clinical Practice