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From the National Institutes of HealthNational Institutes of Health

Cranberry


What is it?

Cranberry is a small, evergreen shrub grown throughout North America. Cranberry has a long history of use among native American Indian tribes, primarily for treating urinary conditions. Juice and extracts from the fruit (berry) are used as medicine.

Cranberry is most commonly used for prevention and treatment of urinary tract infections (UTIs). Cranberry JUICE seems to help prevent UTIs, but so far it doesn’t seem to be effective in treating UTIs.

Cranberry is also used for neurogenic bladder (a bladder disease), as well as to deodorize urine in people with urinary incontinence (difficulty controlling urination). Some people use cranberry to increase urine flow, kill germs, speed skin healing, and reduce fever.

Some people use cranberry for type 2 diabetes, chronic fatigue syndrome (CFS), scurvy, inflammation of the lining around the lung (pleurisy), and cancer.

In foods, cranberry fruit is used in cranberry juice, cranberry juice cocktail, jelly, and sauce. Cranberry juice cocktail is approximately 26% to 33% pure cranberry juice, sweetened with fructose or artificial sweetener.

How effective is it?

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.

The effectiveness ratings for CRANBERRY are as follows:

Possibly effective for...

  • Preventing urinary tract infections (UTIs). Research shows that drinking cranberry juice cocktail can help prevent repeated UTIs in older women and pregnant women. Additional research shows that drinking cranberry juice can also help prevent UTIs in hospitalized patients. Some clinical research also supports the use of cranberry-containing capsules for preventing repeated UTIs.

Possibly ineffective for...

  • Treating type 2 diabetes. Taking cranberry supplements by mouth doesn’t seem to lower blood sugar.

Insufficient evidence to rate effectiveness for...

  • Benign prostatic hyperplasia (BPH). Some research shows that taking dried cranberry capsules, three times daily for 6 months, might improve urinary symptoms and lower blood levels of PSA.
  • Reducing urinary odor in people with bladder control problems. Developing research suggests cranberry juice cocktail might be effective for odor control in these people, but cranberry juice must be taken regularly.
  • Skin healing.
  • Pleurisy.
  • Cancer.
  • Chronic fatigue syndrome (CFS).
  • Other conditions.
More evidence is needed to rate cranberry for these uses.

How does it work?

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People used to think that cranberry worked for urinary tract infections by making the urine acidic and, therefore, unlikely to support the growth of bacteria. But researchers don’t believe this explanation any more. They now think that some of the chemicals in cranberries keep bacteria from sticking to the cells that line the urinary tract where they can multiply. Cranberry, however, does not seem to have the ability to release bacteria which are already stuck to these cells. This may explain why cranberry is possibly effective in preventing urinary tract infections, but possibly ineffective in treating them.

Cranberry, as well as many other fruits and vegetables, contains significant amounts of salicylic acid, which is an important ingredient in aspirin. Drinking cranberry juice regularly increases the amount of salicylic acid in the body. Salicylic acid can reduce swelling, prevent blood clots, and can have antitumor effects.

Are there safety concerns?

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Cranberry is LIKELY SAFE for most people. Cranberry juice and cranberry extracts have been used safely in research. Cranberry juice is LIKELY SAFE for children. But drinking too much cranberry juice can cause some side effects such as mild stomach upset and diarrhea. Drinking more than 1 liter per day for a long period of time might increase the chance of getting kidney stones.

Special precautions & warnings:

Pregnancy and breast-feeding: Cranberries and cranberry juice are safe to consume during pregnancy and breast-feeding. But don't use dietary supplements that contain cranberry products. It is not known if these are safe to use during pregnancy and breast-feeding.

Aspirin allergy: Cranberries contain significant amounts of salicylic acid. Salicylic acid is similar to aspirin. Avoid drinking large quantities of cranberry juice if you are allergic to aspirin.

Diabetes: Some cranberry juice products are sweetened with extra sugar. If you have diabetes, stick with cranberry products that are sweetened with artificial sweeteners.

Kidney stones: Cranberry juice and cranberry extracts contain a large amount of a chemical called oxalate. In fact, there is some evidence that some cranberry extract tablets can boost the level of oxalate in the urine by as much as 43%. Since kidney stones are made primarily from oxalate combined with calcium, healthcare providers worry that cranberry might increase the risk of kidney stones. If you have a history of kidney stones, avoid taking cranberry extract products or drinking a lot of cranberry juice.

Are there interactions with medications?

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Moderate

Be cautious with this combination.

Warfarin (Coumadin)
Warfarin (Coumadin) is used to slow blood clotting. Cranberry might increase how long warfarin (Coumadin) is in the body, and increase the chances of bruising and bleeding. Be sure to have your blood checked regularly. The dose of your warfarin (Coumadin) might need to be changed.

Minor

Be watchful with this combination.

Medications changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates)
Some medications are changed and broken down by the liver. Cranberry might decrease how quickly the liver breaks down some medications. Taking cranberry along with some medications that are broken down by the liver can increase the effects and side effects of some medications. Before taking cranberry, talk to your healthcare provider if you take any medications that are changed by the liver.

Some medications that are changed by the liver include amitriptyline (Elavil), diazepam (Valium), zileuton (Zyflo), celecoxib (Celebrex), diclofenac (Voltaren), fluvastatin (Lescol), glipizide (Glucotrol), ibuprofen (Advil, Motrin), irbesartan (Avapro), losartan (Cozaar), phenytoin (Dilantin), piroxicam (Feldene), tamoxifen (Nolvadex), tolbutamide (Tolinase), torsemide (Demadex), warfarin (Coumadin), and others.

Are there interactions with herbs and supplements?

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There are no known interactions with herbs and supplements.

Are there interactions with foods?

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There are no known interactions with foods.

What dose is used?

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The following doses have been studied in scientific research:

BY MOUTH:
  • For preventing urinary tract infections (UTIs): Cranberry juice 1-10 oz per day has been used. However, the ideal dose has not yet been determined.
  • For preventing UTIs in children: 15ml/kg daily as 30% cranberry concentrate has been used.
  • For use as a urinary deodorizer for incontinent patients: 3-6 oz per day of cranberry juice.
  • For type 2 diabetes: Six capsules (equivalent to 240 mL cranberry juice cocktail) daily for 12 weeks. Encapsulated formulations are often taken in doses of 300-400 mg twice daily.
Approximately 1500 grams of fresh fruit produces 1 liter of juice. Cranberry juice cocktail is approximately 26% to 33% pure cranberry juice, sweetened with fructose or artificial sweetener.

Other names

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Agrio, Airelle à Gros Fruits, Airelle Canneberge, Airelle Européenne, Airelle Rouge, American Cranberry, Arándano, Arándano Americano, Arándano Rojo, Arándano Trepador, Atoca, Atoka, Bearberry, Canneberge, Canneberge à Feuillage Persistant, Canneberge d'Amérique, Canneberge Européenne, Cocktail au Jus de Canneberge, Cranberry Extract, Cranberry Fruit, Cranberry Fruit Juice, Cranberry Juice, Cranberry Juice Cocktail, Cranberry Juice Concentrate, Cranberry Powder, Cranberry Powdered Extract, Craneberry, Da Guo Yue Jie, Da Guo Yue Ju, Da Guo Suan Guo Man Yue Ju, European Cranberry, Extrait de Canneberge, Große Moosbeere, Gros Atoca, Grosse Moosbeere, Jus de Canneberge, Jus de Canneberge à Base de Concentré, Jus de Canneberge Frais, Kliukva, Kliukva Obyknovennaia, Kranbeere, Large Cranberry, Man Yue Ju, Man Yue Mei, Moosebeere, Mossberry, Oomi No Tsuruko Kemomo, Oxycoccus hagerupii, Oxycoccus macrocarpos, Oxycoccus microcarpus, Oxycoccus palustris, Oxycoccus quadripetalus, Petite Cannberge, Pois de Fagne, Pomme des Prés, Ronce d'Amerique, Sirop de Canneberge, Small Cranberry, Trailing Swamp Cranberry, Tsuru-Kokemomo, Vaccinium hagerupii, Vaccinium macrocarpon, Vaccinium microcarpum, Vaccinium oxycoccos, Vaccinium palustre.

Methodology

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To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.methodology (http://www.nlm.nih.gov/medlineplus/druginfo/natural/methodology.html).

References

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To see all references for the Cranberry page, please go to http://www.nlm.nih.gov/medlineplus/druginfo/natural/958.html.

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Last reviewed - 01/17/2012

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Page last updated: 27 September 2012