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Herb library · Herb · Vaccinium macrocarpon, Vaccinium oxycoccos

Cranberry

A North American bog berry, sold mostly for urinary tract infections. Cranberry products may lower the chance of repeat UTIs in women, though findings are inconsistent; cranberry is not a substitute for care when you already have a UTI.

Traditional use

Native Americans and later European settlers used cranberry in dyes, food and medicine; the fruit and leaves were thought to help the bladder, stomach, blood and liver, as well as wounds and scurvy. Today it is promoted mainly for UTIs and repeat UTIs, partly because of interest in options besides antibiotics.

What studies show

  • Limited

    Repeat UTIs in women: many studies, not all high quality. In general, cranberry products may lower the overall risk of symptomatic repeat UTIs in women by about 25 percent, but inconsistent findings leave its effectiveness in question. Since 2020 the FDA has let labels say there is "limited" evidence for this in healthy women ("limited and inconsistent" for cranberry juice drinks).

  • Insufficient

    A UTI you already have: cranberry is not recommended for an existing UTI in any group of people.

  • Limited

    Other higher-risk groups: results were inconsistent in older people in long-term care and in pregnant women, and studies in women having gynecologic surgery or people with multiple sclerosis found no benefit.

Be careful of

Cautions

  • ConditionIf you think you have a UTI, see a clinician for diagnosis and care. Don't use cranberry products instead of it.
  • AmountGenerally safe by mouth, but very large amounts can cause stomach upset and diarrhea, especially in young children.
  • InteractionEvidence conflicts on whether cranberry interacts with the blood thinner warfarin.
  • PregnancyFood amounts appear safe in pregnancy and breastfeeding, but the evidence is not conclusive for larger amounts.
  • Ask a clinicianTalk with a clinician or pharmacist before using this if you take prescription medicines, are pregnant or breastfeeding, or are giving it to a child.

From the old books

What herbals and dispensaries of the past printed. History, in their words.

“A split cranberry, secured in position by a daub of starch, is recommended for boils on the tip of the nose, when a poultice can not be retained in place.”
Harvey Wickes Felter and John Uri Lloyd, King's American Dispensatory (1898), vol. 1, p. 463. See the page of King's American Dispensatory, vol. 1, p. 463 (opens in a new tab) · Read the full passage from King's American Dispensatory, vol. 1, p. 463

Sources

  1. Cranberry: Usefulness and Safety (opens in a new tab) · NCCIH · read September 25, 2026

Reviewed September 25, 2026.