Herb library · Herb · Allium sativum
Garlic
A kitchen bulb also sold as a supplement, mostly for cholesterol and blood pressure. A great deal of research exists; supplements may lower LDL cholesterol a little in people with high cholesterol, and the other effects studied are small or unclear.
Traditional use
Cultivated worldwide and used in food and for health for thousands of years. Ancient writings from Egypt, Greece, and India describe its use for headache, pneumonia, throat conditions, and digestive complaints. Today garlic supplements are sold for cholesterol, blood pressure, blood sugar, cancer risk, and immune function.
Traditional energetics
Galenic (hot or cold, dry or moist)
Hot and dry in the fourth degree. Culpeper's Complete Herbal (1814), p. 218 (opens in a new tab)
What studies show
- Limited
Cholesterol: garlic supplements may lower total and LDL cholesterol to a small extent in people who have high cholesterol. This is the most studied use.
- Limited
Blood pressure: limited evidence suggests supplements may lower blood pressure a little in people with high blood pressure.
- Limited
Blood sugar: supplements may lower blood sugar to a small extent in people with diabetes.
- Limited
Cancer risk: eating garlic does not seem to lower the risk of stomach cancer, and whether it affects the risk of colorectal cancer is uncertain.
- Insufficient
Colds and immune function: very little research. A 2022 review found only two small studies suggesting a possible benefit, both with weaknesses.
Be careful of
Cautions
- NoteTaken by mouth, garlic has been used safely in studies lasting up to 7 years. Side effects include breath and body odor, stomach pain, gas, and nausea.
- InteractionGarlic supplements may raise the risk of bleeding. Tell your clinicians you take them, especially before surgery or if you take anticoagulants or aspirin.
- NoteFresh raw garlic may not be safe on the skin: it can cause severe irritation and chemical burns.
- AllergySome people are allergic to garlic.
- PregnancyGarlic may not be safe by mouth in amounts larger than food amounts during pregnancy or breastfeeding. Little is known about using it on the skin then.
- Ask a clinicianTalk with a clinician or pharmacist before using this if you take prescription medicines, are pregnant or breastfeeding, or are giving it to a child.
From the old books
What herbals and dispensaries of the past printed. History, in their words.
“Many authors quote many diseases this is good for; but conceal its vices.”
“The odor imparted to the breath by garlic and onions, may be very much diminished by chewing roasted coffee grains, or parsley leaves and seeds.”
In scripture
Where the Bible names this plant, and which plant scholars think is meant.
We remember the fish, which we ate in Egypt for nothing; the cucumbers, and the melons, and the leeks, and the onions, and the garlic;
Garlic (Allium sativum), the plant on this page, which is not disputed. Tristram (1898) notes it was much grown in Egypt and Syria. H. B. Tristram, The Natural History of the Bible (1898), p. 448 (opens in a new tab)
Sources
- Garlic: Usefulness and Safety (opens in a new tab) · NCCIH · read September 25, 2026
Reviewed September 25, 2026.