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Botanical illustration of Cranberry
MedicinalSourced entry

Cranberry

Vaccinium macrocarpon

A North American berry best known for helping prevent repeated urinary tract infections. A Cochrane review found it probably lowers the risk in some groups, but it doesn't treat an existing UTI.

Safety at a glance

Tap a box to read the safety notes below. “Nothing recorded” means our sources don't cover it, not that it's safe.

Cranberry may interact with some medicines. If you take any medicine, read Interactions with medicines below and talk to your doctor or pharmacist before using it.

What is Cranberry?

Plant family
Ericaceae, the heather family
Parts used
The fruit
Where it grows
Wet habitats in the northeastern and north-central parts of North America
Genus
Vaccinium
Species
macrocarpon

Also called

American Cranberry, Large Cranberry

Traditionally used for

  • Preventing repeated UTIs (some evidence)
  • Mild bladder infection symptoms (traditional)

Traditionally described as

  • Contains proanthocyanidins (PACs)

Health topics

Where Cranberry appears in symptom search, and why. Being listed doesn't mean it's a proven treatment.

How it's prepared

Common ways Cranberry is prepared or sold. This isn't advice on how to take it; see Safety below.

  • Capsule

    Cranberry is also sold as tablets and capsules, though processing can lower the amount of its active compounds.[1]Health agency

  • Extract

    The European Medicines Agency's monograph covers juice pressed from the fruit, taken by mouth.[2]Health agency

Safety

Interactions with medicines

  • Don't use cranberry products with the blood thinner warfarin, because they may strengthen its effect. Avoid them with tacrolimus too: cranberry juice lowered tacrolimus levels in a kidney transplant patient.[2]Health agency

Who should avoid it

  • Cranberry medicines aren't recommended for men, children or teens under 18, or pregnant women, whose urinary symptoms need medical care. People with kidney problems and repeated UTIs need medical supervision.[2]Health agency

  • If you think you have a UTI, see a health care provider for diagnosis and treatment. Don't use cranberry products instead of a proven treatment.[1]Health agency

Side effects

  • Nausea, diarrhea, indigestion, hives and rash have been reported.[2]Health agency

  • Cranberry taken by mouth is generally thought to be safe, but very large amounts can cause an upset stomach and diarrhea, especially in young children.[1]Health agency

Pregnancy

  • Cranberry seems safe in the amounts found in food during pregnancy and breastfeeding, but there isn't enough evidence for larger amounts. The European Medicines Agency doesn't recommend cranberry medicines at these times.[1]Health agency

Toxicity testing

  • Cranberry concentrate is high in oxalate, which may raise the risk of urinary stones in people who've had them before.[2]Health agency

What does the research say?

Traditional use

These are traditional uses, not proven treatments.

  • Native Americans and later European settlers used cranberry for dyes, food and medicine. The fruit and leaves were thought to help bladder, stomach, blood and liver problems, wounds, diabetes and scurvy. Today it's mainly promoted to prevent urinary tract infections (UTIs).[1]Health agency

  • Based on long-standing use, the European Medicines Agency recognizes cranberry juice as a traditional herbal medicine for adult women, to ease symptoms of mild repeated bladder infections and to help prevent them, after a doctor has ruled out serious conditions. This rests on long use, not on proof from clinical trials.[2]Health agency

Laboratory & animal research

Lab and animal results show what might be worth studying in people. They don't show that the herb has these effects in humans.

  • Cranberries contain proanthocyanidins (PACs), compounds that stop some E. coli bacteria from sticking to the bladder wall. This is thought to be how cranberry may help prevent UTIs. Processing cranberries into tablets or capsules can lower their PAC content.[1]Health agency

Research in people

  • A 2023 Cochrane review of 50 trials with 8,857 people found that cranberry products probably lower the risk of UTIs with symptoms by about 30%. They probably helped women with repeated UTIs, children, and people at risk because of a medical procedure. There may be little or no benefit in older people in care homes, pregnant women, or adults whose bladder doesn't empty fully because of nerve problems.[3]Review or trial

    Technical detail: overall RR 0.70 (95% CI 0.58 to 0.84), moderate certainty; women with recurrent UTI RR 0.74; children RR 0.46; intervention-related susceptibility RR 0.47; institutionalized elderly RR 0.93; pregnancy RR 1.06; neuromuscular bladder dysfunction RR 0.97.

  • Cranberry isn't recommended for treating a UTI you already have. Since 2020, the US Food and Drug Administration has let makers say there is "limited" evidence that certain amounts of cranberry supplements taken daily may lower the risk of repeated UTIs in healthy women.[1]Health agency

In short

Avoid with warfarin or tacrolimus. See a doctor for UTI symptoms.

Sources

  1. [1] Cranberry: Usefulness and Safety — National Center for Complementary and Integrative Health (NIH)Government health agency
  2. [2] European Union herbal monograph on Vaccinium macrocarpon Aiton, fructus — European Medicines Agency, Committee on Herbal Medicinal Products (HMPC)Government health agency
  3. [3] Cranberries for preventing urinary tract infections · DOI: 10.1002/14651858.CD001321.pub7Review or clinical trial

This information is educational and traditional in nature, and is not a substitute for professional medical advice. Unfamiliar word? See what these words mean.