Complementary medicines and safety

Last updated: February 07, 2020

Key points
  • These include herbal medicines (e.g. ginseng, valerian, ginkgo) and dietary supplements (e.g. glucosamine, fish oils, vitamins).
  • Many of these medicines come from 'natural' sources, but that doesn't mean that they are always safe. They have side effects and can interact with prescription and OTC medicines.
  • Homeopathic medicines do not have side effects and don't interact with other medicines.

Info sources

With this topic, more than most, there are many unreliable sources of online informationYou may like to look at our brief guide to evaluating websites about medicines. The following free websites have guides to many herbs and dietary supplements, that often summarise potential interactions, side effects, and warnings:

Ginkgo leaf
✦  Memorial Sloan Kettering website
✦  Mayo Clinic website
✦  Medline Plus
✦  SPS website has a few Q&As about the safety of selected products (use the search engine).

Only use websites where you can be sure of the quality of information such as the ones above, and take care that some products with the same or similar brand name may have different ingredients.

    Asking the right questions 

    If trying to solve a clinical problem related to a complementary medicine, you should ask about the patient's medical history and any other medicines they are taking. However, there are five additional questions that you might find helpful in practice:
    • What are the ingredients of the complementary medicine? Brand names often tell you little, and many products have multiple ingredients. It's helpful to see the original pack so you can read the full list of ingredients and the recommended dose. Some products simply comprise vitamins and minerals within their recommended daily allowance.

    • How long has the patient been taking it? If it was started shortly before the appearance of a new side effect then maybe the medicine is responsible. However, if an alternative medicine has been taken safely alongside existing conventional medicines for years, then an interaction is unlikely. If the patient has not yet started the alternative medicine there is an opportunity to intervene if it might not be safe. 

    • Where did they get it from? Is it a familiar OTC brand bought from a reputable outlet, or a poorly labelled powder sourced from an unfamiliar website? Was it prescribed for them, and if so by whom?

    • Why does the patient want to take it? Has the patient self-diagnosed their medical problem, and would it be helpful for them to see a doctor about it? You may be able to recommend a safer or more evidence-based alternative. Is the patient potentially taking a complementary therapy to treat a side effect from another treatment?

    • Does the patient or a healthcare professional have a particular safety concern? For example, are there symptoms that may be a side effect, or uncertainty about an interaction?

    Generally, you will often be trying to answer the question: "What are the potential risks posed to the patient, taking into account their past medical history and concomitant medicines?"

    You can learn more about this subject, and help make your practice safer, with our 15 minute free e-learning.  Click here to start ➔