Cranberry
Summary
A 2023 Cochrane review of 50 trials found cranberry products cut symptomatic, culture-confirmed UTIs by about 30% (moderate certainty, grade B), with benefit in women with recurrent UTIs, children and people after medical procedures. There was little or no benefit in older adults in care homes or in pregnant women.
Key facts
- Fruit of Vaccinium macrocarpon, used as juice, dried powder or extract; proanthocyanidins (PACs) are the compounds studied[1][2]
- Symptomatic UTIs: risk down about 30% overall (B), including in women with recurrent UTIs (B); no benefit in care-home residents or pregnancy (no effect)[2][3]
- Juice and capsule doses varied; the largest US capsule trial gave 72 mg PACs per day for 1 year. Cochrane found no difference between low, moderate and high PAC doses[2][3]
- None set; cranberry is a food, not a nutrient[1]
- Stomach upset and diarrhea in very large amounts; GI effects not clearly different from placebo in trials[1][2]
- 6 graded human outcomes on this page
- October 10, 2026
How it works
ProposedProanthocyanidins (PACs) in cranberry stop P-fimbriated E. coli from sticking to the cells lining the bladder, which is the proposed reason it lowers UTI risk. Processing into tablets or capsules can lower PAC content.[1][2]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Symptomatic, culture-confirmed UTIs (all groups) | Improved | Grade B | Systematic review · n = 6,211 · 2023 Children and adults at risk of UTI in 26 pooled RCTs Form: cranberry juice, tablets, capsules or powder · Dose: Varied across trials · Duration: Varied across trials Cranberry products lowered UTI risk vs placebo, water or no treatment (RR 0.70, 95% CI 0.58–0.84; moderate certainty), with substantial heterogeneity (I² 69%). | 37947276 (opens PubMed)Source [2] |
| UTIs in women with recurrent UTIs | Improved | Grade B | Systematic review · n = 1,555 · 2023 Women with recurrent UTIs in 8 RCTs Form: cranberry products · Dose: Varied across trials · Duration: Varied across trials Risk fell about a quarter (RR 0.74, 95% CI 0.55–0.99; I² 54%). | 37947276 (opens PubMed)Source [2] |
| UTIs after a medical procedure | Improved | Grade B | Systematic review · n = 1,434 · 2023 People susceptible to UTI because of an intervention, in 6 RCTs Form: cranberry products · Dose: Varied across trials · Duration: Varied across trials Risk fell by about half (RR 0.47, 95% CI 0.37–0.61; I² 0%). | 37947276 (opens PubMed)Source [2] |
| UTIs in children | Improved | Grade C | Systematic review · n = 504 · 2023 Children in 5 RCTs Form: cranberry products · Dose: Varied across trials · Duration: Varied across trials Risk fell by about half (RR 0.46, 95% CI 0.32–0.68; I² 21%). | 37947276 (opens PubMed)Source [2] |
| UTIs in care-home residents, pregnancy and bladder-emptying problems | No effect | No effect | Systematic review · n = 2,718 · 2023 Older adults in care (3 RCTs, 1,489), pregnant women (3 RCTs, 765) and adults with neuromuscular bladder dysfunction (3 RCTs, 464) Form: cranberry products · Dose: Varied across trials · Duration: Varied across trials Little or no difference: RR 0.93 in care-home residents, 1.06 in pregnancy and 0.97 with bladder-emptying problems. | 37947276 (opens PubMed)Source [2] |
| Bacteriuria plus pyuria in nursing-home residents | No effect | No effect | RCT · n = 185 · 2016 Women aged 65+ in 21 Connecticut nursing homes Form: cranberry capsules · Dose: 2 capsules daily, 72 mg PACs in total · Duration: 1 year No difference vs placebo (29.1% vs 29.0%; OR 1.01). Symptomatic UTIs (10 vs 12 episodes), deaths and hospitalizations also did not differ. | 27787564 (opens PubMed)Source [3] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Cranberry juice or juice cocktail | Varies[1] | No human absorption data in our sources.[1] | Very large amounts can upset the stomach; 1 L/day raised urinary oxalate.[1][5] | Recurrent UTI trials (FDA allows only a "limited and inconsistent" evidence claim on juice labels) |
| Cranberry capsules or tablets standardized to PACs | Varies[1] | No human absorption data in our sources. Processing can reduce PAC content.[1] | GI effects not clearly different from placebo in pooled trials.[2] | UTI trials, including 72 mg PACs/day in nursing homes |
| Dried whole cranberry powder | Varies[1] | No human absorption data in our sources.[1] | No specific tolerance data in our sources.[1] | Some UTI trials in the Cochrane review |
Studied doses
Doses studied in human trials ranged from daily juice servings to standardized capsules, and Cochrane found no difference in UTI risk between low, moderate and high PAC doses. The largest US capsule trial used 72 mg of PACs per day for 1 year.[2][3]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Who should be careful
- Kidney stones
- In a metabolic study, 1 L of cranberry juice a day raised urinary calcium and oxalate and increased calcium oxalate saturation by 18%, while lowering uric acid.[5]
- An active UTI
- Cranberry is not a substitute for diagnosis and antibiotics when a UTI is suspected; NCCIH advises seeing a clinician.[1]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Safety
Cranberry is generally considered safe by mouth; the main cautions are very large amounts and kidney stones.
- Stomach upset
- Gastrointestinal side effects probably did not differ from placebo (RR 1.33, 95% CI 1.00–1.77; 10 studies, 2,166 people).[2]
- Large amounts
- Very large amounts can cause stomach upset and diarrhea, particularly in young children.[1]
- Oxalate
- Daily litre-scale juice intake raised calcium oxalate stone risk factors in a small study.[5]
How to read the label
- Label dose vs clinical doseTrials varied widely in dose. The nursing-home trial used 72 mg of PACs a day (the authors equated it to about 20 ounces of juice). Many labels list cranberry powder in milligrams without stating PACs, which cannot be compared.[2][3]
- PAC content can drop in processingTurning cranberries into tablets or capsules can reduce PAC concentration, so the PAC amount matters more than the fruit-powder weight.[1]
- The FDA claim is limitedSince 2020 the FDA has allowed labels to say there is "limited" evidence that specified daily amounts of cranberry supplements may lower recurrent UTI risk in healthy women.[1]
Cost per studied dose, without the sales pitch
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Cost per studied dose
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Frequently asked questions
Does cranberry work for UTIs?
For some groups, yes. A 2023 Cochrane review of 50 trials found about 30% fewer symptomatic, culture-confirmed UTIs overall, with benefit in women with recurrent UTIs, children and people after procedures.[2]
Who does cranberry not help?
Pooled trials found little or no benefit in older adults in care homes, pregnant women and people with bladder-emptying problems. A 1-year US nursing-home trial of capsules also found no effect.[2][3]
How does cranberry compare with antibiotics?
About the same, in limited data: two trials (385 people) found little or no difference in UTI risk between cranberry and preventive antibiotics, with low certainty.[2]
How much cranberry was studied?
Doses varied. The nursing-home trial used 72 mg of PACs daily, and Cochrane found no difference between low, moderate and high PAC doses.[2][3]
Does cranberry interact with warfarin?
The evidence conflicts. A randomized trial of daily cranberry juice found no change in warfarin levels, but NCCIH advises checking with a clinician.[1][4]
Can cranberry cause kidney stones?
It may raise the risk of calcium oxalate stones: 1 L of juice a day raised urinary oxalate and calcium in a small study.[5]
Sources
- [1]Cranberry: Usefulness and Safety (last updated November 2024). NIH National Center for Complementary and Integrative Health, 2024. fact-sheet
- [2]Cranberries for preventing urinary tract infections.. Cochrane Database Syst Rev, 2023. systematic-review
- [3]Effect of Cranberry Capsules on Bacteriuria Plus Pyuria Among Older Women in Nursing Homes: A Randomized Clinical Trial.. JAMA, 2016. RCT
- [4]The absence of an interaction between warfarin and cranberry juice: a randomized, double-blind trial.. J Clin Pharmacol, 2009. RCT
- [5]Effect of cranberry juice consumption on urinary stone risk factors.. J Urol, 2005. crossover-RCT
What changed
- First draft. Every PMID checked against NCBI E-utilities esummary (title and year taken from the record) and abstracts read for the cited rows.
- Adversarial review pass: every number re-read against the Cochrane 2023 abstract (pub7, PMID 37947276) and the trial abstracts; subgroup nulls (care homes, pregnancy, bladder dysfunction) given their own row; warfarin wording matched to the RCT and NCCIH. Page set indexable.