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Research · Supplements

Cranberry

A 2023 Cochrane review of 50 trials found cranberry products cut symptomatic, culture-verified UTIs by 30%, with moderate certainty. Benefit appeared in women with recurrent UTIs, children and people after procedures. Older adults in care, pregnant women and people with bladder emptying problems showed little or no difference. Small studies on urinary oxalate and warfarin disagree.

Add to Bio HackChecked 2026-11-09
Status
Dietary supplement and food in the US. Not approved by the FDA as a drug for any use.
Also called
Vaccinium macrocarpon, cranberry juice, cranberry extract, cranberry capsules, cranberry tablets, cranberry proanthocyanidins, PACs, Pacran
Taken for
UTI, urinary tract infections, bladder health, urinary tract health, recurrent cystitis

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help1

Reported risks2

What people take it for, and what was found

Shown to help1

Strong

Preventing urinary tract infections

Shown to lower symptomatic UTIs by about 30% against placebo or no treatment, including in women with recurrent UTIs and in children. Antibiotics gave similar results.

The numbers and sources
Effect
In a Cochrane review of 50 trials (8,857 people), cranberry products reduced symptomatic, culture-verified UTIs against placebo or no treatment (26 studies, 6,211 people, RR 0.70, 95% CI 0.58 to 0.84, moderate certainty). The risk fell in women with recurrent UTIs (RR 0.74, 95% CI 0.55 to 0.99, 1,555 women), in children (RR 0.46, 504 children) and in people susceptible after an intervention (RR 0.47, 1,434 people). Against antibiotics there was little or no difference (RR 1.03, 95% CI 0.80 to 1.33, 385 people) [1]. A separate meta-analysis of 7 trials in 1,498 healthy women found a 26% lower risk (RR 0.74, 95% CI 0.55 to 0.98) [2]. In 373 women with a recent UTI, one 240 mL cranberry drink a day for 24 weeks gave 39 clinical UTI episodes against 67 on placebo (rate ratio 0.61, 95% CI 0.41 to 0.91), and time to culture-positive UTI did not differ [3]. In 150 women with recurrent UTI, 500 mg of whole cranberry powder a day for 6 months lowered culture-confirmed UTI risk (RR 0.48, 95% CI 0.26 to 0.87) [4].
Population
Women with recurrent UTIs, children, people after catheterization or surgery, older adults in care, pregnant women and adults with neurogenic bladder [1]. Healthy women aged 18 and over with a history of UTI [2][3][4].
Sources
[1], [2], [3], [4]
Caveats
Heterogeneity across all trials was high (I² 69%) [1]. Most trials in the healthy-women meta-analysis were small, and 2 had high loss to follow-up or selective reporting [2]. It was unclear whether juice and tablets or different PAC doses differ, at very low certainty [1].

Doses studied

Trials used juice, tablets and capsules. The Cochrane review found no difference in UTI risk between low, moderate and high doses of proanthocyanidins (PACs) [1]. One trial used one 240 mL serving of cranberry drink a day for 24 weeks [3], another 500 mg of whole cranberry powder a day for 6 months [4], and another 8 oz of 27% cranberry juice twice a day [5].

Risks

Reported risks1

Limited

Urinary oxalate and kidney stone risk factors

Small trials found cranberry tablets and juice mostly raised urinary oxalate, while one found it fell. New stones were not measured.

The numbers and sources
Effect
In 5 healthy volunteers, cranberry concentrate tablets for 7 days raised urinary oxalate by an average of 43.4% [6]. In 15 adults, cranberry tablets for 14 days raised median urinary oxalate by 0.10 mmol a day, and by 1.15 mmol a day when the tablets contained vitamin C [7]. In 24 adults, including 12 calcium oxalate stone formers, 1 L of cranberry juice a day for 7 days raised urinary oxalate from 26.4 to 29.2 mg a day and calcium oxalate saturation by 18%, and lowered urinary uric acid [8]. In 20 men in a crossover trial, 500 mL of cranberry juice a day for 2 weeks lowered oxalate excretion and raised citrate against water [9]. A US Pharmacopeia safety review called the stone data contradictory [10].
Population
Small groups of healthy adults and stone formers [6][7][8][9].
Sources
[6], [7], [8], [9], [10]
Caveats
These studies measured urine chemistry, not stones. All are small and short. No controlled trial measuring new stones was located.

Mixed results1

Limited

Warfarin interaction

Small trials found mostly no change in INR with cranberry in people on warfarin, though one raised INR 30% in healthy men.

The numbers and sources
Effect
In 12 healthy men, 2 weeks of cranberry before a single 25 mg dose of warfarin raised the area under the INR curve by 30%, with no change in warfarin blood levels [11]. In 30 patients on stable warfarin, 240 mL of cranberry juice a day for 2 weeks did not change warfarin levels, and mean INR differed from placebo on only 1 day of the trial [12]. In 10 men on warfarin, 240 mL twice a day for 7 days did not change prothrombin time [13]. A systematic review of food and supplement interactions listed cranberry among the products linked to higher bleeding risk with warfarin [14]. A US Pharmacopeia review found no interaction at 240 to 480 mL of juice a day, with case reports mostly in seriously ill people or people on other medicines [10].
Population
Healthy men [11]. Patients on long-term warfarin [12][13]. Published case reports and studies [10][14].
Sources
[11], [12], [13], [14], [10]
Caveats
The controlled studies are small and short. Case reports cannot give a rate.

Checked, no increase found1

Moderate

Digestive side effects in trials

Gastrointestinal side effects were probably about as common as on placebo, though the estimate allows up to a 77% higher risk.

The numbers and sources
Effect
Gastrointestinal side effects probably did not differ between cranberry and placebo or no treatment (10 studies, 2,166 people, RR 1.33, 95% CI 1.00 to 1.77, moderate certainty) [1].
Population
People in RCTs of cranberry products [1].
Sources
[1]
Caveats
The interval runs from no difference to a 77% higher risk [1].

Claims tested and not found

  1. That cranberry prevents UTIs in older adults living in care. Three studies in 1,489 elderly institutionalized men and women found little or no difference (RR 0.93, 95% CI 0.67 to 1.30, low certainty) [1].
  2. That cranberry prevents UTIs in pregnancy. Three studies in 765 pregnant women found little or no difference (RR 1.06, 95% CI 0.75 to 1.50, low certainty) [1].
  3. That cranberry prevents UTIs in people with bladder emptying problems. Three studies in 464 adults with neuromuscular bladder dysfunction found little or no difference (RR 0.97, 95% CI 0.78 to 1.19, low certainty) [1].
  4. That cranberry juice prevents a second UTI in young women after an acute UTI. In 319 college women, recurrence over 6 months was 20.0% on cranberry juice and 14.0% on placebo [5].

Sources

  1. Williams G, Hahn D, Stephens JH, et al. Cranberries for preventing urinary tract infections. Cochrane Database of Systematic Reviews. 2023. https://doi.org/10.1002/14651858.CD001321.pub6
  2. Fu Z, Liska D, Talan D, et al. Cranberry Reduces the Risk of Urinary Tract Infection Recurrence in Otherwise Healthy Women: A Systematic Review and Meta-Analysis. The Journal of Nutrition. 2017. https://doi.org/10.3945/jn.117.254961
  3. Maki KC, Kaspar KL, Khoo C, et al. Consumption of a cranberry juice beverage lowered the number of clinical urinary tract infection episodes in women with a recent history of urinary tract infection. The American Journal of Clinical Nutrition. 2016. https://doi.org/10.3945/ajcn.116.130542
  4. Stonehouse W, Benassi-Evans B, Bednarz J, et al. Whole cranberry fruit powder supplement reduces the incidence of culture-confirmed urinary tract infections in females with a history of recurrent urinary tract infection: A 6-month multicenter, randomized, double-blind, placebo-controlled trial. The American Journal of Clinical Nutrition. 2025. https://doi.org/10.1016/j.ajcnut.2025.01.022
  5. Barbosa-Cesnik C, Brown MB, Buxton M, et al. Cranberry Juice Fails to Prevent Recurrent Urinary Tract Infection: Results From a Randomized Placebo-Controlled Trial. Clinical Infectious Diseases. 2011. https://doi.org/10.1093/cid/ciq073
  6. Terris MK, Issa MM, Tacker JR. Dietary supplementation with cranberry concentrate tablets may increase the risk of nephrolithiasis. Urology. 2001. https://doi.org/10.1016/S0090-4295(00)00884-0
  7. Redmond EJ, Murphy CF, Leonard J, et al. The influence of dietary supplementation with cranberry tablets on the urinary risk factors for nephrolithiasis. World Journal of Urology. 2019. https://doi.org/10.1007/s00345-018-2344-1
  8. Gettman MT, Ogan K, Brinkley LJ, et al. Effect of cranberry juice consumption on urinary stone risk factors. The Journal of Urology. 2005. https://doi.org/10.1097/01.ju.0000165168.68054.f8
  9. McHarg T, Rodgers A, Charlton K. Influence of cranberry juice on the urinary risk factors for calcium oxalate kidney stone formation. BJU International. 2003. https://doi.org/10.1046/j.1464-410X.2003.04472.x
  10. Madden E, McLachlan C, Oketch-Rabah H, et al. Safety of Cranberry: Evaluation of Evidence of Kidney Stone Formation and Botanical Drug-Interactions. Planta Medica. 2021. https://doi.org/10.1055/a-1497-6241
  11. Mohammed Abdul MI, Jiang X, Williams KM, et al. Pharmacodynamic interaction of warfarin with cranberry but not with garlic in healthy subjects. British Journal of Pharmacology. 2008. https://doi.org/10.1038/bjp.2008.210
  12. Ansell J, McDonough M, Zhao Y, et al. The absence of an interaction between warfarin and cranberry juice: a randomized, double-blind trial. The Journal of Clinical Pharmacology. 2009. https://doi.org/10.1177/0091270009337510
  13. Mellen CK, Ford M, Rindone JP. Effect of high-dose cranberry juice on the pharmacodynamics of warfarin in patients. British Journal of Clinical Pharmacology. 2010. https://doi.org/10.1111/j.1365-2125.2010.03674.x
  14. Tan CSS, Lee SWH. Warfarin and food, herbal or dietary supplement interactions: A systematic review. British Journal of Clinical Pharmacology. 2021. https://doi.org/10.1111/bcp.14404

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