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Some Herbal Supplements May Interact Badly with Prescription Meds, Study Finds

Patients taking antidepressants — as well as those taking herbal supplements to manage symptoms of depression — should be aware of potentially dangerous interactions between herbs and drugs, the authors of a new study conclude.

January 30, 2018

Certain herbal supplements, like St. John’s wort or ginkgo biloba, may pose serious health risks if taken alongside prescription medications, a new study finds. Though these risks are well known among doctors, the authors say, increased patient awareness — and more robust discussion of interactions between supplements and prescription medications — is necessary to avoid unwanted side effects and health ramifications.

The study1, published Monday in the British Journal of Clinical Pharmacology, analyzed 49 case reports of adverse drug reactions (ADRs), as well as two observational studies comprising an additional 15 ADRs. The subjects included patients being treated with prescription medications for depression, anxiety, heart disease, cancer, and kidney transplants. Possible interactions were assessed using Stockley’s Herbal Medicine Interactions and the Roussel Uclaf Causality Assessment Method, a tool for measuring drug-induced liver injury.

Of the 64 cases studied, 51 percent showed “probable” signs of herb-drug interaction, the authors said. Only 8 percent of the interactions were found to be “highly probable,” but less than 4 percent of cases were considered “doubtful.” Patients taking antidepressants, in particular, often experienced worsening symptoms when they combined prescription medications with herbal supplements. In addition, patients with physical ailments who took herbal supplements to treat co-occurring depression frequently experienced blood-clotting issues and other potentially dangerous side effects, the authors said.

The results highlight the need for larger, more robust studies on the potential risks associated with combining medications with herbal supplements, the authors conclude. “This approach will inform drug regulatory agencies and pharmaceutical companies about the need to update information in package inserts of medicines to avoid untoward adverse effects, based on available data,” they write.

The study’s conclusions don’t rule out the use of supplements entirely. Some, like ginkgo and ginseng, have shown positive effects on ADHD symptoms, while herbal remedies like St. John’s wort may help with milder forms of depression when taken properly. The key goal of the study, the authors say, is patient awareness — it’s vitally important that patients disclose to their doctor every medication or supplement they take regularly, so he or she can account for any interactions and keep astride of any possible side effects.

1 Awortwe, Charles, et al. “Critical Evaluation of Causality Assessment of Herb-Drug Interactions in Patients.” British Journal of Clinical Pharmacology, 2018, doi:10.1111/bcp.13490.

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