Search
SectionsIndexFirst Aid
  • Blood Disorders
  • Bone, Joint, and Muscle Disorders
  • Brain, Spinal Cord, and Nerve Disorders
  • Cancer
  • Children's Health Issues
  • Digestive Disorders
  • Disorders of Nutrition
  • Drugs
  • Ear, Nose, and Throat Disorders
  • Eye Disorders
  • Fundamentals
  • Heart and Blood Vessel Disorders
  • Hormonal and Metabolic Disorders
  • Immune Disorders
  • Infections
  • Injuries and Poisoning
  • Kidney and Urinary Tract Disorders
  • Liver and Gallbladder Disorders
  • Lung and Airway Disorders
  • Men's Health Issues
  • Mental Health Disorders
  • Mouth and Dental Disorders
  • Older People's Health Issues
  • Skin Disorders
  • Special Subjects
  • Women's Health Issues
ABCDEFGHI
JKLMNOPQR
STUVWXYZ
  • Emergencies
  • Cardiac Arrest
  • Choking
  • Drowning
  • Injuries
  • Altitude Illness
  • Bee Stings
  • Bites, Animal
  • Bites, Human
  • Bites, Snake
  • Burns
  • Electrical Injuries
  • Eye, Blunt Injury to
  • Eye, Chemical Burns of
  • Fractures
  • Frostbite
  • Head Injury
  • Heatstroke
  • Hypoithermia
  • Lightning Injuries
  • Shock
  • Sprains and Strains
  • Wounds
In This Topic
Special Subjects
Medicinal Herbs and Nutraceuticals
Garlic
Back to Top
Resources
  • About The Merck Manual Home Health Handbook Online Version
  • Anatomical Drawings
  • The One-Page Merck Manual of Health
  • Multimedia
  • Pronunciations
  • Selected Links
  • Weights and Measures
  • Common Medical Tests
  • Drug Names: Generic and Trade
  • Resources for Help and Information
Manuals available online
'/professional/index.html' + bookPageLink
 
'/home/index.html'
These and other Manuals available
in print, online, and as mobile applications.

See more at MerckManuals.com
Sections in Patients & Caregivers
  • Blood Disorders
  • Bone, Joint, and Muscle Disorders
  • Brain, Spinal Cord, and Nerve Disorders
  • Cancer
  • Children's Health Issues
  • Digestive Disorders
  • Disorders of Nutrition
  • Drugs
  • Ear, Nose, and Throat Disorders
  • Eye Disorders
  • Fundamentals
  • Heart and Blood Vessel Disorders
  • Hormonal and Metabolic Disorders
  • Immune Disorders
  • Infections
  • Injuries and Poisoning
  • Kidney and Urinary Tract Disorders
  • Liver and Gallbladder Disorders
  • Lung and Airway Disorders
  • Men's Health Issues
  • Mental Health Disorders
  • Mouth and Dental Disorders
  • Older People's Health Issues
  • Skin Disorders
  • Special Subjects
  • Women's Health Issues
Chapters in Special Subjects
  • Medical Decision Making
  • Surgery
  • Complementary and Alternative Medicine (CAM)
  • Travel and Health
  • Nonspecific Symptoms
  • Disorders of Unknown Cause
  • The Science of Medicine and Clinical Trials
  • Limb Prosthetics
  • Common Imaging Tests
  • Medicinal Herbs and Nutraceuticals
  • Hospital Care
  • Drug Use and Abuse
Topics in Medicinal Herbs and Nutraceuticals
  • Overview of Medicinal Herbs and Nutraceuticals
  • Black Cohosh
  • Chamomile
  • Chondroitin Sulfate
  • Chromium
  • Coenzyme Q10
  • Cranberry
  • Creatine
  • Dehydroepiandrosterone (DHEA)
  • Echinacea
  • Feverfew
  • Fish Oil
  • Garlic
  • Ginger
  • Ginkgo
  • Ginseng
  • Glucosamine
  • Goldenseal
  • Green Tea
  • Kava
  • Licorice
  • Melatonin
  • Milk Thistle
  • S-Adenosyl-L-Methionine (SAMe)
  • Saw Palmetto
  • St. John's Wort
  • Valerian
  • Zinc
 
  • Merck Manual
  • >
  • Patients & Caregivers
  • >
  • Special Subjects
  • >
  • Medicinal Herbs and Nutraceuticals
  • 4
 
Garlic

Share This

Garlic has long been used in cooking and in medicine. When a garlic bulb is cut or crushed, an amino acid byproduct called allicin is released. Allicin is responsible for garlic's strong odor and medicinal properties.

Medicinal Claims: Garlic reduces the normal clotting tendency of particles in the blood that help stop bleeding (platelets). Because garlic stops microorganisms (such as bacteria) from reproducing, it can be used as an antiseptic and antibacterial. In large doses, garlic can slightly reduce blood pressure, overactivity of the intestine, and blood sugar levels. Advocates suggest that garlic lowers levels of low-density lipoprotein (LDL)—the bad—cholesterol. However, at least one well-designed study did not support this beneficial effect. Most studies have used aged garlic extracts. Preparations formulated to have little or no odor may be inactive and need to be studied.

Possible Side Effects: Garlic usually has no harmful effects other than making the breath, body, and breast milk smell like garlic. However, consuming large amounts can cause nausea and burning in the mouth, esophagus, and stomach.

Garlic may interact with drugs that prevent blood clots (such as warfarinSome Trade Names
COUMADIN
), increasing risk of bleeding. Thus, garlic should not be eaten or taken as a supplement 1 week before surgery or before a dental procedure.

Last full review/revision February 2009 by Ara DerMarderosian, PhD

Buy the Book

Mobile Versions

Pronunciations

esophagus

warfarin

Back to Top

Previous: Fish Oil

Next: Ginger

Audio
Figures
Photographs
Pronunciations
Sidebar
Tables
Videos

Copyright     © 2010-2013 Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Whitehouse Station, N.J., U.S.A.    Privacy    Terms of Use