Garlic is an herb that is used in cooking and baking. It has also been used to lower blood pressure and help the body fight illness. Garlic can be eaten as a paste, powder, pill, or extract. It can also be made into a tea, eaten plain, or applied to the skin.


300 milligrams 2 to 3 times daily

What Research Shows

Likely Effective

May Be Effective

May Not Be Effective

  • Peripheral arterial occlusive disease —may not improve walking distance H1
  • Preeclampsia—may not prevent I1, I2

Editorial process and description of evidence categories can be found at EBSCO NAT Editorial Process.

Safety Notes

It is likely safe to take garlic in small doses for a short time, but allergic reactions are possible. Raw garlic and large doses of garlic may not be safe. Not enough studies have been done to say whether it is safe to use for a long period or used on the skin by women who are pregnant or breastfeeding.


Talk to your doctor about any supplements or therapy you would like to use. Some can interfere with treatment or make conditions worse.


A. Cardiovascular Disease

A1. . Stabler SN, Tejani AM, et al. Garlic for the prevention of cardiovascular morbidity and mortality in hypertensive patients. Cochrane Database Syst Rev. 2012;(8):CD007653.

A2. Schwingshackl L, Missbach B, et al. An umbrella review of garlic intake and risk of cardiovascular disease. Phytomedicine. 2016;23(11):1127-1133.

B. Common Cold

B1. Lissiman E, Bhasale AL, et al. Garlic for the common cold. Cochrane Database Syst Rev. 2014;(11):CD006206.

C. Diabetes

C1. Ashraf R, Khan RA, et al. Garlic (Allium sativum) supplementation with standard antidiabetic agent provides better diabetic control in type 2 diabetes patients. Pak J Pharm Sci. 2011;24(4):565-570.

C2. Hou LQ, Liu YH, et al. Garlic intake lowers fasting blood glucose: meta-analysis of randomized controlled trials. Asia Pac J Clin Nutr. 2015;24(4):575-582.

D. High Blood Pressure

D1. Wang HP, Yang J, et al. Effect of garlic on blood pressure: a meta-analysis. J Clin Hypertens (Greenwich). 2015;17(3):223-231.

D2. Xiong XJ, Wang PQ, et al. Garlic for hypertension: A systematic review and meta-analysis of randomized controlled trials. Phytomedicine. 2015;22(3):352-361.

D3. Ried K. Garlic Lowers Blood Pressure in Hypertensive Individuals, Regulates Serum Cholesterol, and Stimulates Immunity: An Updated Meta-analysis and Review. J Nutr. 2016 Feb;146(2):389S-396S.

D4. Reinhart KM, Coleman CI, et al. Effects of garlic on blood pressure in patients with and without systolic hypertension: a meta-analysis. Ann Pharmacother. 2008 Dec;42(12):1766-1771.

D5. Ried K, Frank OR, et al. Effect of garlic on blood pressure: a systematic review and meta-analysis. BMC Cardiovasc Disord. 2008 Jun 16;8:13.

E. High Cholesterol

E1. Khoo YS, Aziz Z. Garlic supplementation and serum cholesterol: a meta-analysis. J Clin Pharm Ther. 2009;34(2):133-145.

E2. Shabani E, Sayemiri K, et al. The effect of garlic on lipid profile and glucose parameters in diabetic patients: A systematic review and meta-analysis. Prim Care Diabetes. 2019 Feb;13(1):28-42.

E3. Sun YE, Wang W, et al. Anti-hyperlipidemia of garlic by reducing the level of total cholesterol and low-density lipoprotein: A meta-analysis. Medicine (Baltimore). 2018 May;97(18):e0255.

E4. Posadzki P, AlBedah AM, et al. Complementary and alternative medicine for lowering blood lipid levels: A systematic review of systematic reviews. Complement Ther Med. 2016 Dec;29:141-151.

F. Gingivitis

F1. Zini A, Mann J, et al. The Efficacy of Aged Garlic Extract on Gingivitis-A Randomized Clinical Trial. J Clin Dent. 2018;29(2):52-56.

G. Metabolic Syndrome

G1. van den Driessche JJ, Plat J, et al. Effects of superfoods on risk factors of metabolic syndrome: a systematic review of human intervention trials. Food Funct. 2018 Apr 25;9(4):1944-1966.

H. Peripheral Arterial Occlusive Disease

H1. Jepson RG, Kleijnen J, et al. Garlic for peripheral arterial occlusive disease. Cochrane Database Syst Rev. 2013 Apr 30;(4):CD000095.

I. Preeclampsia

I1. Dante G, Pedrielli G, et al. Herb remedies during pregnancy: a systematic review of controlled clinical trials. J Matern Fetal Neonatal Med. 2013 Feb;26(3):306-312.

I2. Meher S, Duley L. Garlic for preventing pre-eclampsia and its complications. Cochrane Database Syst Rev. 2006 Jul 19;(3):CD006065.

Last reviewed March 2020 by EBSCO NAT Review Board Eric Hurwitz, DC
Last Updated: 6/29/2020

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