Are there any complementary and alternative medicines that should be avoided in patients on cancer chemotherapy?

This Q&A focuses on complementary therapies and alternative medicines  (CAMs) with pharmacological activity such as herbal medicines, vitamins and minerals, and summarises information on common characteristics of CAMs that clinicians need to consider when using together with cancer chemotherapy. It includes recommendations on commonly used CAMs that should be avoided or used with caution in patients on cancer chemotherapy.

  • The effects of many complementary and alternative medicines (CAMs) in patients on cancer chemotherapy are not well documented due a lack of well-designed safety and efficacy studies.
  • Understanding the common characteristics of CAMs can help patients and clinicians make informed decisions. This includes looking at whether the CAM is an antioxidant, has anticoagulant or hormonal effects, or is likely to have pharmacokinetic interactions with cancer chemotherapy.
  • This Q&A discusses the following:
  • – CAMs with antioxidant properties, e.g. vitamins A, C and E and their potential interactions with chemotherapy drugs.
  • – The hormonal effects of phytoestrogens and their use in patients with gynaecological cancers
  • – Examples of CAMs with anticoagulant effects and those with pharmacokinetic interactions with chemotherapy drugs e.g. garlic, echinacea, ginkgo, ginseng, St John’s Wort.
  • More research is needed before definitive recommendations can be made. In the meantime, clinicians should discuss the (lack of) evidence and any theoretical concerns they have with patients before coming to a decision.