Cranberry

© Steven Foster

This fact sheet provides basic information about cranberry—common 

names, what the science says, potential side effects and cautions, and 

resources for more information.

Common Names—cranberry, American cranberry, bog cranberry

Latin Name—Vaccinium macrocarpon

Cranberries are the fruit of a native plant of North America. These red 

berries are used in foods and in herbal products. Historically, cranberry 

fruits and leaves were used for a variety of problems, such as wounds, 

urinary disorders, diarrhea, diabetes, stomach ailments, and liver 

problems. More recently, cranberry has been used as a folk or traditional 

remedy for urinary tract infections or Helicobacter pylori (H. pylori) infections 

that can lead to stomach ulcers, or to prevent dental plaque. Cranberry has 

also been reported to have antioxidant and anticancer activity.

The berries are used to produce beverages and many other food products, 

as well as dietary supplements in the form of extracts, capsules, or tablets.

What the Science Says

• There is some evidence that cranberry can help to prevent urinary 

tract infections; however, the evidence is not definitive, and more 

research is needed. Cranberry has not been shown to be effective as 

a treatment for an existing urinary tract infection.

• Research shows that components found in cranberry may prevent 

bacteria, such as E. coli, from clinging to the cells along the walls of 

the urinary tract and causing infection. There is also preliminary 

evidence that cranberry may reduce the ability of H. pylori bacteria 

to live in the stomach and cause ulcers.

• Findings from a few laboratory studies suggest that cranberry may 

have antioxidant properties and may also be able to reduce dental 

plaque (a cause of gum disease).

• NCCAM is funding studies of cranberry, primarily to better 

understand its effects on urinary tract infection. The Office of 

Dietary Supplements and other National Institutes of Health (NIH) 

agencies are also supporting cranberry research; for example, the 

National Institute on Aging is funding a laboratory study of

potential anti-aging effects. 
Side Effects and Cautions

• Drinking cranberry juice products appears to be safe, although excessive amounts could 

cause gastrointestinal upset or diarrhea.

• People who think they have a urinary tract infection should see a health care provider for 

proper diagnosis and treatment. Cranberry products should not be used to treat infection.

• There are some indications that cranberry should be used cautiously by people who take 

blood-thinning drugs (such as warfarin), medications that affect the liver, or aspirin.

• Tell all your health care providers about any complementary health practices you use. Give 

them a full picture of what you do to manage your health. This will help ensure 

coordinated and safe care. For tips about talking with your health care providers about 

complementary and alternative medicine, see NCCAM’s Time to Talk campaign at 

nccam.nih.gov/timetotalk/. 

Sources

Cranberry. Natural Medicines Comprehensive Database Web site. Accessed at www.naturaldatabase.com on May 11, 2009.

Cranberry (Vaccinium macrocarpon). Natural Standard Database Web site. Accessed at www.naturalstandard.com on 

May 11, 2009.

Jepson RG, Craig JC. Cranberries for preventing urinary tract infections. Cochrane Database of Systematic Reviews. 

2008;(1):CD001321.

Klein MA. Cranberry (Vaccinium macrocarpon) Aiton. In: Coates P, Blackman M, Cragg G, et al., eds. Encyclopedia of Dietary 

Supplements. New York, NY: Marcel Dekker; 2005:143-149.

For More Information

Visit the NCCAM Web site at nccam.nih.gov and view Using Dietary Supplements Wisely

(nccam.nih.gov/health/supplements/wiseuse.htm).

NCCAM Clearinghouse

Toll-free in the U.S.: 1-888-644-6226

TTY (for deaf and hard-of-hearing callers): 1-866-464-3615

E-mail: info@nccam.nih.gov

PubMed®

Web site: www.ncbi.nlm.nih.gov/sites/entrez

NIH Office of Dietary Supplements

Web site: www.ods.od.nih.gov

NIH National Library of Medicine’s MedlinePlus

Cranberry Listing: www.nlm.nih.gov/medlineplus/druginfo/natural/958.html

This publication is not copyrighted and is in the public domain. Duplication is encouraged.

NCCAM has provided this material for your information. It is not intended to substitute for the medical 

expertise and advice of your primary health care provider. We encourage you to discuss any decisions 

about treatment or care with your health care provider. The mention of any product, service, or therapy 

is not an endorsement by NCCAM.

National Institutes of Health

♦♦♦

U.S. Department of Health and Human Services

D291

Created September 2005

Updated April 2012