Table 7.

Potential harmful effects of complementary and alternative medicine

CAM	Potential harmful effects and interactions
Fish oil14,15	Inhibits platelet aggregation and fibrinogen. Decreases plasma viscosity and increases bleeding time
Evening primrose14,16	Inhibits platelet aggregation. Decreases effect of phenytoin resulting in poor control of epilepsy
Garlic14,17,18	Inhibits platelet aggregation, decreases plasma viscosity and increases bleeding time. It is fibrinolytic and potentiates coumadin. Also, it interacts with hypoglycaemics and MAOI
Cranberry juice19	Interacts with warfarin causing unstable INR
Aloe14,20,21	Potentiation of cardiac glycosides and anti-arrythmics. It is cathartic, can cause electrolyte disturbances and predisposes to hypokalaemic cardiac dysrythmias
Vitamin E14,22	Inhibits platelet aggregation
Echinacea18	Inhibits cytochrome CYP3A4. Potentiates barbiturate toxicity and hepatotoxicity of amiodarone, steroids, methotrexate and halothane. Causes immunosuppression and decreases efficacy of cyclosporine and steroids
Ginseng14,17,18	Inhibits platelet aggregation and platelet activating factor. It has negative inotropic and anti-arrythmic activity. Decreases warfarin effect. Interacts with MAOI and antidepressants. Can cause hypertension and has anxiolytic activity
St John's Wort14,17,18,23–26	Potent inducer of hepatic cytochrome P-450, CYP3A4 and P-glycoprotein: interacts with and reduces the activity of cyclosporine, indinavir, digoxin, amitriptyline and oral contraceptives. It binds to GABA and benzodiazepine receptors; has anxiolytic activity and may lead to prolonged postoperative sedation
Ginkgo biloba14,17,18	Inhibits platelet aggregation and platelet activating factor. Inhibits fibrinogen, decreases plasma viscosity and has anti-arrythmic activity. Interacts with anticonvulsants, MAOI and barbiturate anaesthetics
Valerian18	Binds with GABA and benzodiazepine receptors. It is anxiolytic, causes muscle relaxation and has potential for CNS depression
Ginger14,18	Inhibits platelet aggregation and thromboxane synthetase. Positive inotropic effect; can cause hyperglycaemia and interacts with warfarin
Kava14,18	Inhibits platelet aggregation, cyclooxygenase and arachidonic acid. Binds GABA receptors and has anxiolytic and muscle relaxing activity
Melatonin14	Anxiolytic, risk of peri-operative excessive sedation
Ephedra14,18,27	It is sympathomimetic; can cause hypertension, cardiovascular and cerebrovascular accidents. Interacts with ephedrine, halothane, oxytocin, MAOI, cardiac glycosides
Saw palmetto18,28	Causes cyclooxygenase inhibition, platelet dysfunction, tachycardia and angina.