The term ‘complementary medicines’ encompasses many medicinal products, and may include herbal preparations, vitamins, minerals, nutritional supplements and traditional medicines such as those from Chinese, Ayurvedic (Hindu), and Aboriginal cultures. Complementary medicines are also often called ‘alternative’ or ‘natural’ medicines. ‘CAM’ is normally used to refer to all substances which can be categorised as complementary and alternative medicine.

The Therapeutic Goods Administration does not require scientific evidence of efficacy in order to list complementary medicines, such as is required for registered medicines; instead, their availability may be based on acceptance of traditional knowledge, potential health benefits, and evidence that they will “do no harm”.

Half of Australians use CAMs, spending above $2.3 billion annually, the majority being women between 40 and 60 years of age, well educated, and well paid. The widespread use of CAMs may be driven by a number of factors, including:

  • a desire for good health and wellbeing
  • a desire for some self-control in the management of their health
  • a lack of trust in orthodox medicine
  • a deep-rooted belief that complementary medicines are safer than prescription medicines, because they are ‘natural’

These perceptions are enhanced by the many media reports of serious adverse effects associated with commonly used medications.

Adverse Effects

Although, in many cases, convincing scientific evidence to support the safety and efficacy of CAMs is lacking, their use in patients with cardiovascular disease is widespread, increasing the potential for interactions with prescription medicines. In addition, though widely perceived to be natural and therefore safe, many CAMs do have side effects. When used in combination with prescription medicines, the risk of adverse effects may increase. This can be very important in patients with cardiovascular disease, where:

  • they may be taking medications with a narrow therapeutic index (e.g. warfarin)
  • they may be taking multiple medications
  • they may be frail and elderly
  • kidney/liver function may be impaired

Table 1 provides just a small sample of some of the potential effects and problems when CAMs are used in patients with cardiovascular disease. Information available varies in quality, relying on actual case reports or results from animal studies and human clinical trials. Many interactions may be theoretical only or of limited clinical significance.

Table 1. Uses and Interactions of some CAMs. **Should be stopped 7-14 days before surgery.

CAM Common Uses Adverse Effect of Interaction
Angelica (dong quai) Gynaecological disorders ↑ Risk of bleeding with anticoagulants (e.g. warfarin), antiplatelet drugs (e.g. aspirin, clopidogrel), NSAIDs (e.g. ibuprofen) **
Bilberry Circulatory problems, diarrhoea **
Capsicum Shingles, trigeminal/diabetic neuralgia **
Celery Arthritis, gout, fluid retention **
Chamomile Insomnia, eczema, colic **
Coenzyme Q10 Congestive Cardiac Failure (CCF), Hypertension (HT), statin adverse effects ↓ Effect of warfarin, Additive antihypertensive effects
Evening primrose oil Atopic eczema, premenstrual syndrome (PMS), rheumatoid arthritis (RA), multiple sclerosis **
Fish oil Cardiovascular disease, atrial fibrillation (AF), RA, high triglycerides **
Garlic High cholesterol, HT, heart disease **
Ginger High cholesterol, motion sickness **
Ginkgo Poor circulation, cognitive disorders **
Ginseng Immune system, cognitive function **
Glucosamine Osteoarthritis ↑ Effect of warfarin
Grapefruit juice Weight loss, cardiovascular health ↑ Effect of statins, calcium channel blockers (CCB)
Green tea Cognitive performance, weight loss ↓ Effect of warfarin (contains vitamin K)
Guarana Weight loss, enhanced athletic performance, cognitive function ↑ Heart rate, BP, additive effect with diuretics **
Hawthorn CCF, HT May potentiate digoxin, antihypertensives, nitrates, erectile dysfunction medicines
Red clover Menopausal symptoms, benign prostate hypertrophy (BPH), bone mineral density (BMD) **
Saw palmetto BPH, increased sexual vigour **
St John’s Wort Depression, seasonal affective disorder (SAD), PMS, menopausal mood symptoms ↓ Effect of pre-op medications (e.g. midazolam, fentanyl, propofol), CCB, warfarin, and statins
↓ Levels of digoxin/amiodarone
↑ Effect of clopidogrel


Surgery Risk

Risks associated with the use of CAMs in patients undergoing planned surgery should be identified and assessed. A number of CAMs may increase the risk of complications during or after surgery. Those with antiplatelet or anticoagulant effects can increase the risk of bleeding, when used in combination with antiplatelet medications such as aspirin or clopidogrel, anticoagulants (warfarin), or NSAIDs with antiplatelet activity. CAMs which need to be treated with caution include fish oil, chamomile, dong quai, ginkgo, ginger, guarana and ginseng. Others, such as St John’s Wort, commonly used for depression and other mood disorders, may interfere with the action of pre-operative or anaesthetic medications.

The use of CAMs must always be discussed with medical practitioners before planned surgery; some may need to be ceased 7-14 days beforehand as indicated in Table 1.

Numerous complementary medications are purported to be beneficial in patients with cardiovascular disease, though the evidence is not always convincing. Coenzyme Q10 is one such medication, widely advocated to reduce or prevent side effects such as myalgia in patients on ‘statin’ therapy. Its routine use is probably not warranted, but it may have a place in patients who do develop myalgia whilst on a statin. Garlic may be of benefit in patients with hypertension, whilst evidence for the use of ginseng and ginkgo in cardiovascular disease is not convincing. There is, however, compelling evidence for the beneficial effects of fish oil for primary and secondary prevention of heart disease, AF, and hypertriglyceridaemia.

An Ethical Dilemma for Pharmacists

Some consumers may insist on purchasing a CAM, even when scientific evidence for its benefit is lacking, and there is potential for adverse effects and interactions with their prescription medications. In these situations, consumers should be fully informed of any potential risks, and strongly encouraged to keep their GP, cardiologist, or any other relevant health professionals up-to-date with any complementary medicines they are taking. This may be particularly important if surgery is planned in the future.

A respect for the consumer’s right to have some self-control in the decision-making about their health management will encourage good communication, and increase the likelihood of disclosure of any alternative therapies to enable suitable management.


  1. Pharmaceutical Society of Australia. Australian pharmaceutical formulary and handbook: the everyday guide to pharmacy practice. 22nd ed. Deakin West: Pharmaceutical Society of Australia; 2012.
  2. eTG complete [CD-ROM]. Melbourne: Therapeutic Guidelines Limited; 2010 Mar.
  3. Tachjian A, Maria V, Jahangir A. Use of Herbal Products and Potential Interactions in Patients with Cardiovascular Disease. J Am Coll Cardiol. 2010; 55(6): 515–25.