Botanical Name(s):

Vaccinium macrocarpon. Family: Ericaceae

Other Name(s):

bearberry, craneberry

General Description:

The cranberry is an evergreen plant native to the northeastern United States. It has been used traditionally for the prevention and treatment of urinary tract infections. Although it has fallen in and out of favor in medicine, cranberry is currently recognized as an effective agent to help prevent uncomplicated urinary tract infections, particularly in older women.

Cranberries are considered a foodstuff and are used in commercial quantities for cooking. They are most notably recognized as a garnish for salad and used in gelatin salad, cranberry sauce and jelly, and cranberry cocktail. Cranberry cocktail is most often used as a source of cranberry to prevent urinary tract infections. However, potent cranberry extracts are available and can be taken as pills by those who do not like the tartness or flavor of cranberry juice.

Cranberry contains a variety of constituents (anthocyanin, catechin, triterpenoids, quinic acid) that have been shown to decrease the adherence of bacteria to the bladder walls, therefore decreasing the likelihood of urinary tract infections.

Medically Valid Uses:

Drinking cranberry juice regularly can help prevent urinary tract infections from developing. Cranberry juice prevents bacteria from clinging to the bladder walls and increases the acidity of the urine. Cranberry is most useful as a preventive measure rather than a cure for an existing urinary tract infection. However, its use, along with standard treatment for a urinary tract infection, can hasten improvement. Constituents in cranberries have the following properties:

  • They inhibit certain chemicals necessary for E. coli (a common urinary infectious agent) to attach to the bladder wall.

  • They increase the acidity of urine (decrease the pH).

  • They increase the amount of formaldehyde produced in the presence of methenamine (a drug used to treat urinary tract infections).

Unsubstantiated Claims:

Please note that this section reports on claims that have NOT yet been substantiated through scientific studies.

Cranberry juice is also claimed to help cure yeast infections. When consumed regularly, it is claimed to help prevent recurrences of yeast infections.

The high levels of vitamin C in cranberry juice may help reduce the frequency and severity of upper respiratory infections. In addition, cranberry may help relieve postnasal drip.

Cranberry juice may also help prevent kidney stones by reducing the amount of calcium in the urine and decreasing the pH (increasing the acidity) of the urine. High levels of urinary calcium have been linked to the development of kidney stones as has consistently high pH (alkaline) urine.

Dosing Format:

Cranberry is found in the form of berries, capsules (concentrated cranberry extracts), juice and tea. For over-the-counter cranberry concentrates, follow the instructions on the package. Cranberry juice is generally recommended in amounts ranging from 6 to 10 ounces per day, usually divided between meals.

Side Effects, Toxicity and Interactions:

There are no known side effects or significant food or drug interactions associated with cranberry.

Additional Information:

Click here for a list of reputable Web sites with general information on nutrition.


  1. Ahuja S, Kaack B, Roberts J. Loss of fimbrial adhesion with the addition of Vaccinium macrocarpon to the growth medium of P-fimbriated Escherichia coli. J Urol. 1998;159(2):559-62.

  2. Foxman B, Geiger AM, Palin K, Gillespie B, Koopman JS. First-time urinary tract infection and sexual behavior. Epidemiology. 1995;6(2):162-8.

  3. Fleet JC. New support for a folk remedy: cranberry juice reduces bacteriuria and pyuria in elderly women. Nutr Rev. 1994;52(5):168-70.

  4. Avorn J, Monane M, Gurwitz JH, Glynn RJ, Choodnovskiy I, Lipsitz LA. Reduction of bacteriuria and pyuria after ingestion of cranberry juice [see comments]. JAMA. 1994;271(10):751-4.

  5. Schmidt DR, Sobota AE. An examination of the anti-adherence activity of cranberry juice on urinary and nonurinary bacterial isolates. Microbios. 1988;55(224-225):173-81.

  6. Sobota AE. Inhibition of bacterial adherence by cranberry juice: potential use for the treatment of urinary tract infections. J Urol. 1984;131(5):1013-6.

  7. Kinney AB, Blount M. Effect of cranberry juice on urinary pH. Nurs Res. 1979;28(5):287-90.

  8. Nahata MC, McLeod DC. Lack of effect of ascorbic acid, hippuric acid, and methenamine (urinary formaldehyde) on the copper-reduction glucose test in geriatric patients. J Am Geriatr Soc. 1980;28(5):230-3.

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