Discover the importance of safety when using herbs. Learn about the potential side effects and risks of incorrect usage.
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Overview
All herbs and herbal supplements should be prescribed by a qualified therapist who knows your health concerns. While herbs are seen as natural, they are not always safe for some people or situations.
Even herbs you have used before may not be okay now, as they may:
- interact with your cancer treatment
- interfere with or make your cancer treatment less effective
- make side effects of treatment worse.
Always take your herbs as prescribed just like you would other medicines. Taking the wrong dose (e.g. a higher dose) or combination, or using the wrong part of the plant, may be poisonous (toxic) or cause side effects, including damage to the liver or kidneys.
Not all Ayurvedic and Chinese medicines have been screened for harmful substances including pesticides, harmful heavy metals such as lead and mercury, or prescription medicine ingredients.
Make sure herbs and supplements you take are prescribed for you or approved by your treatment team, and from a TGA-approved source.
For information on the effects of specific herbs and plants, visit:
- Memorial Sloan Kettering Cancer Center – and search for “herbs” or download the About Herbs app to your smartphone
- Cancer Choices – for a supplement and other therapies database.
For safety of essential oils, see Aromatherapy.
Many pharmacies, chemists, supermarkets and health food shops sell herbal preparations. For more information on the safety, labelling and regulation of these products, visit tga.gov.au.
Tips for using herbal medicines
There are things you can do to use herbal products safely:
- Buy herbal products from a qualified therapist or reputable supplier.
- Ask for any preparation your therapist makes to be clearly labelled in English with your name, date, quantity, ingredients, dose, directions, any safety information, and the therapist’s contact details.
- If you buy products online, choose a reputable pharmacy website and check that the products have an AUST L, AUST L(A) or AUST R number, showing it has been approved by the Therapeutic Goods Administration (TGA). Visit tga.gov.au and search for “Buying health products online”.
- Avoid products from other countries bought online. They aren’t covered by the same quality and safety regulations as those sold in Australia. They may not include the ingredients that are listed on the label and the quality and dosage can vary from very low to high.
- Follow instructions on how to prepare and take herbs. Like any medicine, taking the right dose of herbal remedies at the right time is important for safety.
- Check the label for any warnings about side effects and drug interactions. Talk to your doctor and complementary therapist about possible side effects and what to do if you experience them or feel otherwise unwell.
- Ask your doctor, pharmacist or complementary therapist to check for interactions between your cancer, the conventional treatments and herbal therapies.
- Never self-prescribe herbal medicines, even if you think they are safe. Always check with a qualified and experienced practitioner.
- Report adverse reactions to any kind of medicine or herbal remedy to your therapist or doctor. If the reaction is serious, call Triple Zero (000) or go to the emergency department.
Taking care with herbs and supplements
Some common herbs and supplements have been shown to cause harmful interactions with cancer treatments, including surgery, radiation therapy and chemotherapy. Ask your surgeon or oncologist whether you need to stop taking any herbs or supplements before treatment. It is also important to take care with vitamin and mineral supplements.
| St John’s wort | Used for mild to moderate depression. Shown to stop some chemotherapy drugs and other medicines working properly. May increase skin reactions to radiation therapy. If you are feeling depressed, ask your doctor about other treatments. |
| ginseng | May need to be avoided for some hormone-sensitive cancers, such as breast or prostate cancer. |
| echinacea | Should be avoided with some immunotherapy treatments. May increase the risk of bleeding, especially during chemotherapy. |
| curcumin/ turmeric | Can affect drug metabolism (e.g. tamoxifen) if used with some treatments (e.g. cyclophosphamide, doxorubicin). May also help some other treatments. Interactions depend on the drug, so talk to a qualified practitioner. |
| black cohosh | Often used for menopause symptoms (e.g. hot flushes), but not proven to help. Clinical trials show it’s relatively safe, but shouldn’t be used if you have liver damage. No evidence supports its use for people with cancer. |
| fish oil, ginkgo biloba and garlic supplements | May have a blood-thinning effect, which can cause bleeding. This could be harmful for those people with low platelet levels (e.g. from chemotherapy) or having surgery. |
| green tea | Has been shown to stop the cancer drug bortezomib from working properly. |
Tell your complementary therapists and other health professionals about any and all herbs and supplements you use before, during or after cancer treatment. This will help them give you the best possible care.
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A/Prof Geraldine McDonald, Director Patient Experience and Wellbeing, Peter MacCallum Cancer Centre, VIC; Laura Carman, 13 11 20 Consultant, Cancer Council Victoria; A/Prof Christine Carrington, Senior Consultant Pharmacist Cancer Services, Princess Alexandra Hospital and Metro South Health and The University of Queensland, QLD; Kellie Giannarelli, Consumer; Dr Suzanne Grant, Senior Research Fellow, Integrative Oncology, NICM Health Research Institute, Chris O’Brien Lifehouse, NSW; Vivienne Hansen, Bush and Western Herbal Medicine Practitioner, WA; Karla Jaji, Administration Officer, Nepean Cancer and Wellness Centre, NSW; Dr Laura Kirsten, Senior Clinical Psychologist, Nepean Cancer Services, Nepean Blue Mountains Local Health District, NSW; A/Prof Judith Lacey, Director of Supportive Care and Integrative Oncology, Chris O’Brien Lifehouse, NSW; Adjunct Professor Danforn Lim, Western Sydney University and University of Technology Sydney, NSW; Dr David Mizrahi, Senior Research Fellow and Accredited Exercise Physiologist, The Daffodil Centre, University of Sydney and Cancer Council NSW; Professor Avni Sali AM, Founder and Director, National Institute of Integrative Medicine, VIC; Gillian Thompson, Consumer; A/Prof Kate Webber, Medical Oncologist, Monash Health, VIC; Tanya Wells, Integrative Oncology Consultant and Naturopath, Melbourne Integrative Oncology Group, VIC; Prof Kate White, Professor Cancer Nursing, Cancer Care Research Unit, The Daffodil Centre, University of Sydney and Cancer Council NSW.
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