This information describes the common uses of Cranberry, how it works, and its possible side effects.

Common Name

Mossberry, Sassamanash, Bounceberry

How It Works

Cranberry juice or extracts have not been shown to treat or prevent cancer. It may be helpful for urinary tract infections (UTIs) in limited populations, but there is not enough evidence to recommend it for UTI prevention.

Cranberries contain compounds known as proanthocyanidins that have been shown to prevent bacteria from attaching to the bladder wall, which could cause UTIs. Human studies suggest it may be helpful for this purpose in some limited populations, including prostate cancer patients, but overall evidence is conflicting. Cranberry may also prevent bacteria from attaching to the stomach lining and areas in the mouth. Although lab studies suggest activity with several types of cancer cells, this has yet to be confirmed in human studies.

In patients who are prone to kidney stones, regular use of cranberry should be limited as it contains oxalates, a compound found in the most common form of kidney stones.

Purported Uses

  • Prevention and treatment of urinary tract infections (UTIs)
    The evidence for this claim is mixed.
  • Anticancer effects
    Lab studies show that cranberry juice extract and isolated compounds can inhibit various types of cancer cells, but this has not been confirmed by clinical trials.
  • Prevention of stomach ulcers
    Cranberry juice may help to prevent or suppress H. pylori infection.
  • Prevention of atherosclerosis
    Although one study in healthy volunteers does not suggest benefit, another study in diabetic men suggests cranberry juice may help to reduce heart disease risk factors.
  • Prevention of gum disease/cavities
    In the lab, cranberry juice prevents bacteria from attaching to one another thereby slowing down plaque formation.

Do Not Take If

  • You are taking warfarin: Because data is mixed on whether cranberry juice may increase bleeding, usage of cranberry juice should be monitored by a healthcare professional, if not avoided. Case reports of bleeding and death in 2 elderly patients who used cranberry juice and warfarin have occurred.

  • You are taking CYP450 substrate drugs: Cranberry may increase blood levels of these drugs or their adverse effects.

  • You are taking UGT substrate drugs: Cranberry may increase the risk of side effects for these drugs.

  • You have a history of kidney stones: Cranberry contains high concentrations of oxalate, a component common to kidney stones.

  • You are taking Tacrolimus: The serum levels of tacrolimus dropped when taken along with cranberry extract. The levels returned to desired range after stopping cranberry intake.

Side Effects

  • Nausea, vomiting and diarrhea have occurred with large amounts of cranberry juice (3 cups daily).

Case reports

  • Increased International Normalized Ratio (INR) and/or bleeding: Several cases were due to suspected interactions between cranberry juice and warfarin.

  • Internal hemorrhage resulting in death: In 2 patients, following concurrent use of warfarin and cranberry juice.