• Complementary medicines can cause unwanted effects as well as beneficial effects. 
  • It is important to tell all your healthcare professionals about all the medicines you are taking, including complementary medicines.
  • Discuss the possible benefits and harms of using complementary medicines with your healthcare professionals before you start taking them.

Complementary medicines include vitamins and minerals, natural and herbal medicines, alternative and holistic remedies, traditional remedies, homeopathic preparations and aromatherapy (essential) oils. 

It is important to tell all your healthcare professionals about any complementary medicines you are taking. This is because complementary medicines can interact with other medications, and can increase the risk of side effects.

Complementary medicines can interact with other medicines

People often think complementary medicines are safe and will not cause any problems because they come from natural sources. This is not always the case. 

Natural substances can still be harmful. And, while the source of some complementary medicines is ‘natural’, the products themselves may be made in similar ways to conventional medicines.

Complementary medicines can cause side effects. They can also interact with prescription medicines, alcohol and other drugs, and other complementary medicines to cause side effects.

For these reasons, it’s important to tell all your healthcare professionals about all the medicines you are taking, including prescribed medicines, over-the-counter medicines and complementary medicines.

For example, some complementary medicines can interfere with cancer treatments. If you are about to receive cancer treatment, talk to your doctor, nurse or pharmacist about any other medicines you are taking or thinking of trying.

Interactions with prescription medicines

Interactions between complementary medicines and prescription medicines can occur. For example: 

  • the medicines may have similar active ingredients that act in the same way, or 
  • the complementary medicine may increase or reduce the effectiveness of the prescription medicine.

Some interactions between complementary medicines and prescription medicines that could put your health at risk include: 

  • Echinacea may interact with antipsychotic or antidepressant medications. 
  • Ginseng may decrease the effectiveness of many medications, including calcium channel blockers, chemotherapy and HIV medications, some blood pressure and cholesterol-lowering medications, and some antidepressants. 
  • Goldenseal interacts with many medications. 
  • Ginkgo biloba may increase the risk of bleeding in people taking the anticoagulant medicine warfarin.
  • St John’s wort can reduce the effectiveness of many over-the-counter and prescription medications used to treat blood pressure and heart problems, HIV, cancer, depression and anxiety. It can also reduce the effectiveness of anaesthetics, immunosuppressant medications and oral contraceptives. 

Side effects of complementary medicines

Some examples of complementary medicines that can cause side effects include: 

  • echinacea – different types of side effects have been reported, including abdominal pain, swelling, shortness of breath, nausea, itchy skin, rash, redness of the skin and hives 
  • feverfew – can cause nausea, digestive problems and bloating
  • asteraceae plants (from the daisy family, including feverfew, echinacea, dandelion and chamomile) – side effects include allergic dermatitis, asthma and hay fever. 

The way some complementary medicines are used also needs to be considered. Some side effects may be caused by the way the medicine is used, rather than the medicine itself. 

For example, some people who take blood thinning medicine after an essential oil massage have reported significant bruising. In this case, it was most likely the massage, rather than the essential oils, that was the cause of the bruising.

Report using complementary medicines

To avoid putting your health at risk, tell your healthcare professionals if you are using complementary medicines. They will need to know: 

  • the type and name of any complementary medicines you are taking
  • how often you take the medicine and the dose
  • the amount of active ingredient in each dose – it may be easier to bring the medicine with you (you need to use the botanical names of herbal medicines and essential oils to avoid confusion caused by the common names)
  • how long you have been taking the medicine and why you are taking it
  • the health benefits that you expect from taking the medicine
  • whether the medicine has worked for you.

Make sure you tell your healthcare professionals about any changes to complementary medicines you are taking.

If your healthcare professional does not support you taking the complementary medicine and advises you to stop taking it, don’t assume that they are biased against complementary medicines. Ask why they have made this recommendation. There may be good medical reasons why you should not take a particular complementary medicine, such as when there is an increased risk of interactions with other medicines or side effects. 

Many people don’t report using complementary medicines

About half the people who use complementary medicines do not tell all their healthcare professionals. The reasons for this may include: 

  • their healthcare professionals do not ask them whether they use complementary medicines
  • they do not think that healthcare professionals will know much about complementary medicines 
  • they think that products are ‘natural’ and ‘safer’
  • they are concerned that their healthcare professionals will be judgemental or negative
  • they are worried that healthcare professionals will discourage use of complementary medicines.

Check with your doctor before using complementary medicines

Talk to your doctor about the benefits and risks of your chosen complementary medicine before you start taking it. It is important that you have a correct diagnosis before you treat any condition, otherwise the benefits of appropriate treatment might be delayed and put your health at risk.

It is strongly recommended that you consult your healthcare professional before taking complementary medicines if you are: 

  • pregnant 
  • intending to become pregnant
  • breastfeeding
  • scheduled for an operation or medical investigation
  • a child
  • an older person
  • diagnosed with a serious disease (or have been previously).

Surgery and tests and complementary medicines

Ask your healthcare professional what to do about all your medicines if you need to have an investigation or surgery.

If you are scheduled for any medical investigation or surgery, you may need to stop taking your complementary medicines or adjust the doses some time before the procedure is scheduled to take place. 

Choose complementary medicines carefully

For your safety and effectiveness of treatment, avoid self-prescribing any medicine, including complementary medicines. Always see a registered health practitioner. 

If you decide to buy complementary medicines ‘over the counter’, read the labels on all packages and containers. Choose products that are made to Australian standards and have an ‘Aust L’ or ‘Aust R’ number on the package. This means the medicine meets Australian manufacturing and safety standards and is less likely to be contaminated.

Medicines bought in other countries or bought online may not be made to the same standard.

Where to get help

  • In an emergency, call triple zero (000)
  • Your GP (doctor)
  • Nurses, especially specialist nurses such as diabetes educators or cancer nurses
  • Pharmacists
  • Other healthcare professionals, such as registered complementary therapists
  • Medicines Line Tel. 1300 MEDICINE (1300 633 424) – for information on prescription, over-the-counter and complementary medicines 
  • Adverse Medicine Events (AME) Line Tel. 1300 134 237 – to report and discuss possible side effects from your medicine
  • Victorian Poisons Information Centre Tel. 13 11 26 – seven days a week, 24 hours a day – for advice about poisonings, suspected poisonings, bites and stings, mistakes with medicines and poisoning prevention advice.
  • NURSE-ON-CALL Tel. 1300 60 60 24 – for expert health information and advice (24 hours, 7 days)

More information

Complementary and alternative care

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Alternative systems and therapies

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This page has been produced in consultation with and approved by: NPS MEDICINEWISE

Last updated: May 2019

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