Garlic - western medicine

The medicinal properties of garlic are now scientifically recognised. It is widely available in different forms in Britain as over-the-counter supplements, particularly to treat the blood conditions and as an antiviral medicine.

Active compounds

Photograph of cloves of garlic.
Image: Cloves of garlic.

Various sulphur-containing compounds occur in garlic. One such compound is called alliin. Crushing or chopping garlic may also promote enzyme reactions and allow other compounds to form. Studies show that these compounds may be responsible for various effects including pain relief, antiworm, antibacterial, antifungal, antiviral, antioxidant, anticancer, blood glucose lowering, blood pressure lowering and liver protection.

Other research shows that garlic may help lower cholesterol, prevent blood clots and spasms, act as an expectorant and alleviate swellings, sores and acne.


Garlic is generally a very safe plant. Occasional reports show that adverse effects have occurred in humans. These include a burning sensation in the mouth and intestine, sickness, and odour from the breath and the body. It may also cause a reaction in the skin of some people, possibly due to the sulphur-containing compounds. Because of this, garlic should not be placed directly on the skin.

Garlic may interfere with some prescribed medicines. For example, those used for preventing blood clots could be enhanced by garlic. There may also be an increased risk of bleeding with the use of garlic in patients undergoing surgery.

Few experimental or clinical studies have been conducted to assess the use of garlic in pregnant or breastfeeding women. In traditional medicine it has been reputed to promote abortion and contractions of the uterus. Consumption of garlic by breastfeeding women may alter the taste and smell of breast milk and so alter the feeding behaviour of babies.

This information is provided for general interest only. It is not intended as guidance for medicinal use. Further information on using herbal medicines is available.