Complementary medicines explained

Complementary medicines are taken by millions of Australians and sold in supermarkets, health food stores, pharmacies and on the internet. Find out more about them, and how to use them safely.


What are complementary medicines?

Complementary medicines include:

  • natural and herbal medicines
  • alternative or holistic remedies
  • traditional remedies
  • homeopathic preparations
  • aromatherapy oils
  • vitamins and minerals (although these can be part of medical treatment too)
  • some nutritional supplements
  • bush medicines.

Like all medicines, complementary medicines can have benefits and side effects, cause allergic reactions, or interact with prescription medicines. They still need to be used with care.

Is it a medicine?

A lot of people don’t realise that complementary products, such as herbal remedies, vitamins, minerals and nutritional supplements, are medicines too.

Medicines are substances that are meant to change the way your body deals with illness or injury, or to maintain your health and wellbeing.

They can come in many forms, such as tablets, liquids, inhalers, drops, patches, creams, lotions, pessaries, suppositories or injections.

You can get them from a pharmacist, with or without prescription, or from supermarkets, health food stores, herbalists, naturopaths and the internet.

Seek advice from a qualified person when choosing a complementary medicine. Ask about:

  • suitable brands or formulations
  • how much to take
  • how often to take the medicine, and
  • what side effects and interactions to look out for.

As with all medicines, tell your health professional about any complementary medicines you are currently taking. That way, you can avoid potentially harmful interactions with your prescription or pharmacy medicines.

What dose should I take?

Many complementary medicines are available in a variety of strengths and they may contain several active ingredients. It can be difficult to work out what is the best option or to compare alternative brands.

If you are choosing a medicine, find out as much as you can about the medicine and its use. Read the label so you know the active ingredients it contains and the amount of each.

If you change from one brand of a complementary medicine to another, be aware that the amount of any active ingredient may be different to your usual brand. This may mean the effect on any prescription medicines you might also take could be different to what you are used to and may trigger an interaction or an effect that you did not have before.

Can I mix complementary and prescription medicines? 

Complementary medicines may not mix well with prescription medicines. They could make your prescribed medicine act more weakly or strongly than your doctor intends. That’s why it is important to tell your health professional about any medicine that you take, complementary or otherwise.

An example: St John’s wort

St John’s wort is a plant (Hypericum perforatum) that grows wild in Europe and Asia and is an introduced weed in North and South America and Australia. It has been used for mental health conditions for centuries, and is available as a herbal preparation in Australian pharmacies.

Make sure you tell your health professional if you are taking St John’s wort so you can avoid interactions with your other medicines.

St John’s wort mostly makes other medicines less effective. This is the case with:

  • birth control pills
  • warfarin and other medicines used to thin the blood
  • epilepsy medicines
  • digoxin, a medicine used for heart conditions
  • HIV medicines
  • cancer medicines
  • medicines used to prevent rejection after an organ transplant
  • asthma medicines

St John’s wort may interact with some antidepressants and migraine medicines and increase the risk of side effects. 

St John’s wort has shown some benefit in clinical trials for mild to moderate depression, but not for more severe depression. Make sure you talk to your health professional if you think you are depressed so you get the best treatment for your situation.

Like all medicines, St John’s wort can also have side effects. The most common side effects of St John’s wort include dry mouth, dizziness, diarrhoea, nausea, increased sensitivity to sunlight, and fatigue.

Learn more about Hypericum on Medicine Finder

How effective are complementary medicines?

Some complementary medicines have been tested in good-quality scientific trials to show that they are effective, but most have not.

Complementary medicines undergo less testing than prescription and pharmacy medicines do before they can be sold in Australia. This means less is known about their effectiveness, side effects and interactions.

Manufacturers of complementary medicines sold in Australia still have to comply with quality and safety standards for their products and have some evidence to back up their claims.

For more information on the Government rules for complementary medicines sold in Australia, see the Therapeutic Goods Administration’s webpage on the regulation of complementary medicines in Australia.

An example: fish oil

One complementary medicine that has been tested is fish oil. 

Scientific trials have shown that fish oils that are high in omega-3 fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) can lower triglycerides and increase high-density lipoprotein (HDL) cholesterol (the good cholesterol). 

Fish oil may be recommended for people with high triglyceride levels. 

Where can I find good information on complementary medicines?

There are thousands of websites about complementary medicines. However, many of these are designed to sell products and the information they provide may not be reliable.

Some good websites with information about complementary medicines include:

Learn more about finding good information about medicines.