Dietary And Herbal Supplements Have Potential Harmful Drug Interactions

Certain herb and dietary supplements (HDS) can produce potentially dangerous drug interference, especially among people taking medication for cardiovascular or nervous system issues.

25 Oct 2012 --- These findings are part of an extensive new research review published in the International Journal of Clinical Practice.

The research team analyzed 54 review articles and 31 original studies. They established that the largest problems were caused by interactions between prescribed drugs and HDS that had ingredients such as St John's Wort, calcium, iron, ginkgo, and magnesium.

Over the past few years, consumer use of HDS has risen at a great pace. Many patients with chronic disease or cancer use them and take them simultaneously with prescribed medication.

Co-author Dr Hsiang-Wen Lin from the College of Pharmacy, China Medical School, Taiwan, says, "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."

Important results of the study include:

- Using 213 HDS entities and 509 prescribed medications, 882 HDS-drug interactions were covered in terms of their components and severity.

- Warfarin, insulin, aspirin digoxin, and ticlopidine had the largest number of documented interactions with HDS.

- Over 42 percent of the drug interactions were produced by the HDS changing the pharmacokinetics of the prescribed drugs (the process by which a drug is taken in, distributed, broken down and eliminated by the body).

- More than 26 percent of the total were classified as major interactions.

- There were 152 contraindications, the most common of which involved the gastrointestinal system, neurological system, and andrenal/genitourinary diseases.

- The biggest number of contraindications came from flaxseed, echinacea, and yohimbe.

Dr. Lin explains:

   "Our extensive review clearly shows that some HDS ingredients have potentially harmful drug interactions that are predominately moderate in their severity. It also showed that herbal and botanical remedies were more likely to have documented drug interactions and contraindications than the other dietary supplements, such as vitamins, minerals and amino acids."


In an editorial on this research, Professor Edzard Ernst, Emeritus Professor, University of Exeter, believes that the authors conducted an extensive overview of an interesting and potentially critical subject.

He says:

    "Survey after survey shows that large proportions of the population are trying 'natural' remedies for illness-prevention, all sorts of ailments, diseases or for states of reduced well-being. Most experts therefore agree that the potential for such interactions is substantial."


Professor Ernst thinks despite the amount of interactions between HDS and prescribed drugs, this research is just a small starting point.

He believes these study results are a call for more intense research, increased education and awareness of possible HDS prescriptions by patients and healthcare professionals, as well as government input on this crucial public health issue.

Ernest concludes, "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."