Contraindications and Precautions
Patients with bleeding abnormalities should avoid therapeutic doses of garlic. Although usual dietary intakes are likely to be safe prior to major surgery, suspend the use of high-dose garlic supplements 1 week before, as garlic may increase bleeding risk.
If being used as part of a topical application, a test patch is advised before more widespread application.
Garlic is not recommended at doses greater than usual dietary intakes.
Practice Points / Patient Counselling
• Garlic is both a food and a therapeutic medicine capable of significant and varied pharmacological activity.
• It has antioxidant, antimicrobial, antiplatelet, antithrombotic, antihypertensive, lipid-lowering, anti-atherosclerotic and vasoprotective activity.
• It also enhances microcirculation and may have hypoglycaemic, anti-inflammatory and immunostimulant activity.
• Garlic is used as a treatment for many common infections, to reduce the incidence of colds, improve peripheral circulation and manage hyperlipidaemia and hypertension.
• Increased consumption of garlic has been associated with a decreased risk of stomach and colorectal cancer, according to a review of the epidemiological evidence.
• Several important drug interactions are possible with garlic (refer to significant interactions).
Answers to Patients’ Frequently Asked Questions
What will this herb do for me?
Garlic has many different actions in the body and is used to treat conditions such as elevated blood pressure, cholesterol levels, poor peripheral circulation and common infections such as the common cold, flu and athletes foot. Research suggests it may be effective in all of these conditions; however, in some cases, the effect is small.
When will it start to work?
This varies greatly, depending on the reason for use. For example, garlic has been shown to improve microcirculation within 5 hours of ingestion, whereas slowing down of the atherosclerotic process or cancer protective effects are likely to require several years’ continuous use.
Are there any safety issues?
When garlic is taken at doses above the usual dietary levels, it may interact with a number of medications. Also, it should not be taken by people with bleeding disorders and use should stop at least 2 weeks before major surgery.