Medically reviewed on Jun 7, 2018
What is Garlic?
Garlic is a perennial bulb with a tall, erect flowering stem that grows up to 1 m. The leaf blade is flat, linear, solid, and approximately 1.25 to 2.5 cm wide, with a pointed top. The plant produces pink to purple flowers that bloom from July to September in the Northern Hemisphere. The bulb is strong smelling and contains outer layers of thin sheathing leaves surrounding an inner sheath that encloses the clove. Often the bulb contains 10 to 20 cloves that are asymmetrical in shape, except for those closest to the center.
Allium, stinking rose, rustic treacle, nectar of the gods, camphor of the poor, poor man's treacle, da-suan, la-suan.
What is it used for?
Garlic was used as money in ancient Egypt. Its virtues were described in inscriptions on the Great Pyramid of Cheops. Folk uses of garlic have ranged from the treatment of leprosy in humans to managing clotting disorders in horses. Physicians prescribed the herb during the Middle Ages to cure deafness, and the American Indians used garlic as a remedy for earaches, gas, and scurvy. In World War II, garlic extracts were used to disinfect wounds. During the 1800s, physicians routinely prescribed garlic inhalation for the treatment of tuberculosis, and raw garlic applied as a poultice continues to be used by naturopaths today.
Despite the widespread use of garlic for heart/blood vessel health and prevention of the common cold, evidence to support these uses is lacking. Garlic does not appear to lower blood sugar, cholesterol, or blood pressure by a meaningful amount. Extracts of garlic or its chemical constituents may have a role in the prevention of some cancers; however, adequate clinical evidence is lacking.
What is the recommended dosage?
The following doses are recommended: 2 to 5 g of fresh raw garlic; 0.4 to 1.2 g of dried garlic powder; 2 to 5 mg garlic oil; 300 to 1,000 mg of garlic extract (as solid material). Take with food. Clinical trials have evaluated 180 mg of allicin daily for prevention of the common cold, and at least 5.5 g of raw garlic for the prevention of prostate cancer.
Do not use if a known allergy to garlic or its constituents exists.
Garlic may be used safely in pregnancy and breast-feeding at usual doses. However, consumption by breast-feeding mothers may change the infant's behavior during breast-feeding, causing prolonged attachment to the breast and increased sucking. Use to induce menstruation has been documented.
Garlic may affect blood concentrations of anti-HIV drugs; caution is advised. Increasing the effects of warfarin is also possible; caution is advised, especially prior to surgery.
Body odor and bad breath are the most common complaints after consuming garlic preparations. Mild ill effects (eg, bloating, gas, nausea) have been commonly reported with use. Garlic burns have been documented when applied to skin. Consuming large amounts may increase the risk of bleeding after surgery. Allergy, asthma, skin reactions, and severe, whole-body allergic reactions have been reported.
There is little information regarding the toxicology of garlic. Crude garlic fed to rats for 30 days resulted in lower testosterone and altered sperm production.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.