Medically Reviewed on 5/6/2022

Generic Name: cranberry

Brand and Other Names: American cranberry, black cranberry, European cranberry, low cranberry, mossberry, Oxycoccus macrocarpus, trailing swamp cranberry, Vaccinium edule, Vaccinium erythrocarpum, Vaccinium macrocarpon, Vaccinium occycoccus, Vaccinium vitis

Drug Class: Herbals

What is cranberry, and what is it used for?

The American cranberry, Vaccinum macrocarpon, is an evergreen shrub that grows in the swamplands of North America. Cranberry is used to prevent urinary tract infections (UTIs) and as a urinary deodorizer for incontinent patients. Cranberry is also used for many other ailments such as type 2 diabetes (diabetes mellitus), chronic fatigue syndrome, and other disorders, however, there is no reliable evidence to support these uses.

Cranberry contains compounds such as flavonoids and proanthocyanidins, and organic acids including salicylate. Cranberry is a rich source of vitamin C, useful as a dietary supplement for scurvy, a condition caused by vitamin C deficiency. Cranberry has antibacterial, antioxidant and anti-inflammatory properties. Cranberry may be eaten as fresh or dried fruit, drunk as juice or juice cocktail, or taken as capsule supplements.

Urinary tract infections are most often caused by Escherichia coli bacteria, and they grow by adhering to the inner lining of the urinary tract. Cranberry prevents the growth of E. coli by preventing their adhesion to the urinary tract surface. Preliminary studies show cranberry may also prevent the adhesion of Helicobacter pylori, which causes peptic ulcers.

Cranberry does not kill bacteria and must not be used instead of antibiotics, it cannot treat an existing infection. Cranberry is useful in preventing UTIs, especially in women predisposed to recurrent UTIs, who have the risk of superinfections and antibiotic resistance with repeated antibiotic courses.

Suggested uses of cranberry include the following:


  • Do not take cranberry if you have a history of kidney stones; cranberry has high oxalate content and can increase the risk of stone formation
  • Cranberry products may be sweetened; use with caution if you are diabetic
  • Use with caution if you have atrophic gastritis, an inflammatory gastric condition or hypochlorhydria, a condition with low level of stomach acid
  • Cranberry may cause hypersensitive reactions
  • Cranberry contains salicylate; use with caution if you have aspirin allergy
  • Interaction with blood thinners such as warfarin can increase the risk of bleeding; use with caution

What are the side effects of cranberry?

Common side effects of cranberry include:

This is not a complete list of all side effects or adverse reactions that may occur from the use of this drug.

Call your doctor for medical advice about serious side effects or adverse reactions. You may also report side effects or health problems to the FDA at 1-800-FDA-1088.

What are the dosages of cranberry?

There isn’t an established standard dose of cranberry.

Suggested dosing:

Urinary Tract Infection (UTI), Prevention


  • Cranberry juice cocktail (26% cranberry juice): 10-16 oz/day orally
  • Cranberry juice: 15 mL twice a day orally


400 mg twice a day orally

Topical use

Urinary Deodorizer for Incontinent Patients

Cranberry juice cocktail

  • 3-6 oz/day orally


How much urine does the average adult pass each day? See Answer


  • Cranberry overdose can cause stomach upset and diarrhea. Discontinue cranberry immediately, and if symptoms persist, seek medical help or contact Poison Control.

What drugs interact with cranberry?

Inform your doctor of all medications you are currently taking, who can advise you on any possible drug interactions. Never begin taking, suddenly discontinue, or change the dosage of any medication without your doctor’s recommendation.

  • Cranberry has no known severe, serious, or moderate interactions with other drugs.
  • Mild Interactions of cranberry include:
    • Warfarin

The drug interactions listed above are not all of the possible interactions or adverse effects. For more information on drug interactions, visit the RxList Drug Interaction Checker.

It is important to always tell your doctor, pharmacist, or health care provider of all prescription and over-the-counter medications you use, as well as the dosage for each, and keep a list of the information.

Check with your doctor or health care provider if you have any questions about the medication.

Pregnancy and breastfeeding

  • There isn’t reliable information on the safety and benefits of cranberry juice or supplements in pregnant or breastfeeding women.
  • Small amounts consumed in foods may be safe, however, check with your doctor. Avoid cranberry juice and supplements.

What else should I know about cranberry?

  • Cranberry is generally recognized as safe, particularly as fresh or dried fruits
  • Studies show limited evidence of cranberry’s efficacy in preventing UTIs, but not its treatment
  • Seek medical help for diagnosis and treatment of urinary tract infections


Cranberry extract is used to prevent urinary tract infections (UTIs) and as a urinary deodorizer for incontinent patients. Cranberry is also used for many other ailments such as diabetes type II, chronic fatigue syndrome, and other disorders. Common side effects of cranberry include stomach upset, reflux, nausea, diarrhea, stomach pain (rare), headaches, elevation of blood glucose levels, kidney stone formation, and increased risk for urinary tract cancer due to oxalate stones. Avoid cranberry juice and supplements if pregnant or breastfeeding.

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You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Medically Reviewed on 5/6/2022