Do cranberry and d-mannose supplements prevent urinary infections?

Cranberry has the best evidence of the three. The latest Cochrane review found that cranberry products reduced the risk of symptomatic, culture-verified urinary tract infections (UTIs) in women with recurrent infections, in children, and in people prone to UTIs after a procedure. D-mannose did not beat placebo in a large 2024 trial, and bearberry (uva-ursi) is a traditional herb whose safety depends on the dose and on who takes it. None of them is a treatment for an infection you already have.

This guide covers what each ingredient was tested for, what dose the studies used, and how supplements we reviewed compare. It is general information and not medical advice. A suspected UTI needs a urine test and a clinician.

Does cranberry prevent urinary tract infections?

For some people, probably yes. The 2023 Cochrane review (updated from a review first published in 1998) included 50 studies and 8,857 randomized participants. Across 26 studies that could be pooled (6,211 participants), cranberry products cut the risk of symptomatic, culture-verified UTIs with a risk ratio of 0.70 (95% CI 0.58 to 0.84), in moderate-certainty evidence.

The result depended on who took it:

• Women with recurrent UTIs: risk ratio 0.74 (95% CI 0.55 to 0.99), from 8 studies and 1,555 participants.
• Children: risk ratio 0.46 (5 studies, 504 participants).
• People susceptible after an intervention: risk ratio 0.47 (6 studies, 1,434 participants).
• Older people in institutions, pregnant women, and adults with incomplete bladder emptying: little or no benefit.

The NIH's National Center for Complementary and Integrative Health (NCCIH) summarizes this as a possible 25 percent lower risk of symptomatic recurrent UTIs in women, with inconsistent findings across studies. It also states that cranberry is not recommended as a treatment for an existing UTI in any population.

What is the catch with cranberry capsules?

There are three catches.

First, the active ingredient is thought to be proanthocyanidins (PACs), which may keep bacteria from sticking to the bladder wall. NCCIH notes that processing cranberries into tablets or capsules can reduce the PAC concentration, which can lower a product's potential effectiveness. A capsule is not automatically equivalent to the juice or extract in a trial.

Second, the Cochrane authors could not show that dose matters. They found no difference in UTI risk between low, moderate and high PAC doses, and the certainty was very low on whether tablets and juice differ. So "30% PAC" on a label is not a guarantee of anything, but a label that hides the amount is a bigger problem.

Third, the compared groups are narrow. Compared with antibiotics, cranberry products made little or no difference to symptomatic, culture-verified UTIs in two studies (385 participants), so the review does not argue that cranberry replaces a prescription. And since 2020 the FDA has allowed a label claim that there is "limited" evidence that specified daily amounts of cranberry supplements may reduce the risk of recurrent UTIs in healthy women, per NCCIH. "Limited" is the official word.

If you take warfarin or another blood thinner, NCCIH says evidence about an interaction with cranberry is conflicting, so talk to your provider first.

Does d-mannose prevent UTIs?

The largest placebo-controlled trial we found says no. The 2024 MERIT trial in JAMA Internal Medicine enrolled 598 women with recurrent UTIs across 99 UK primary care centers. They took 2 g of d-mannose powder or a matching placebo daily for 6 months. A medically attended UTI occurred in 150 of 294 women (51.0%) on d-mannose and 161 of 289 (55.7%) on placebo, a difference of -5% (95% CI -13% to 3%, P = 0.26). No secondary outcome differed either. The authors concluded that d-mannose should not be recommended for prophylaxis in this patient group.

A 2026 overview of 27 systematic reviews of non-antibiotic prevention in women with recurrent UTIs agrees in tone. It found that cranberry and methenamine hippurate are supported by systematic reviews, as is vaginal estrogen after menopause, while reviews of probiotics, d-mannose, herbal medicine, acupuncture and vaccines concluded that stronger evidence is needed.

That is a statement about one dose in one group of women. It does not prove that d-mannose never helps anyone, but it removes the case for paying a premium for it as a UTI shield.

What about bearberry (uva-ursi)?

Bearberry leaf (Arctostaphylos uva-ursi) has a long traditional use for lower urinary tract complaints. Its main constituent, arbutin, is converted in the body to hydroquinone, which is why safety is the first question, not the last.

A 2013 toxicology review of bearberry leaf preparations described a therapeutic recommended daily dose as 420 mg of hydroquinone derivatives calculated as anhydrous arbutin. It estimated that this dose leads to a maximum free hydroquinone exposure of 11 micrograms per kilogram of body weight per day, below the 100 micrograms per kilogram per day level it used as a negligible-risk threshold, and concluded that use under the recommended conditions is safe. That is a review of regulated herbal medicines at defined doses, not of any supplement blend, and it does not cover long-term or high-dose use.

For other groups, the NIH's LactMed database says uva-ursi should generally be avoided while breastfeeding because of a lack of data and its potential toxicity. A German trial design (REGATTA) that tested uva-ursi against a single dose of the antibiotic fosfomycin defined its dose as 3 x 2 units of 105 mg arbutin a day for 5 days, which is 630 mg a day for a short course, under medical supervision. That is a very different setting from an over-the-counter capsule taken for weeks.

How do supplements we reviewed use these ingredients?

The FemiPro review is the clearest example, because it holds cranberry and bearberry together. The label lists cranberry extract (30% proanthocyanidins) and bearberry leaf inside a 350 mg blend of four herbs, with no amount per herb. The review points out that a 420 mg arbutin dose alone is larger than the whole 350 mg blend, so the capsule cannot deliver a traditional bearberry dose. It also notes that no trial of the finished capsule is shown, that the sales page sells it for sudden urinary leaks, and that urinary leaks and recurrent infections need a doctor's evaluation.

Several oral-health products list cranberry as well. The research above is about the urinary tract, so a cranberry line in a tooth or gum product does not borrow that evidence:

• DentalPrime: cranberry powder, no amount stated. The review says cranberry is studied mainly for urinary bacterial adhesion, with some early oral research. It does have a 365-day refund window.
• DentiLock: cranberry powder among seven ingredients, none with an amount.
• BioDentex: cranberries in a blend of six named ingredients, none with an amount.
• DentaBiome: cranberry extract, no amount and no percent PAC.

For how we weigh missing doses, see our review method. To see other women's health listings side by side, visit the women's health category.

A short checklist before buying a urinary supplement

• Do you have symptoms now (burning, urgency, fever, back pain, blood in urine)? See a clinician first. Cranberry, d-mannose and bearberry are not treatments.
• Does the label state the cranberry amount and the PAC content, or hide them in a blend?
• Does the product list bearberry or uva-ursi? Check pregnancy, breastfeeding and medicine interactions with a pharmacist, and look for the arbutin amount.
• Is the study cited about the same form, such as juice versus capsule, and the same kind of person?
• Does the page promise to stop recurrent infections or leaks? Treat that as a claim that needs a trial of the exact product.
• Do you know the refund terms? See the ClickBank refund guide.

FAQ

Can cranberry supplements treat a UTI?

No. NCCIH says cranberry is not recommended as a treatment for an existing UTI in any population, and that people who think they have one should see a health care provider. The studies are about preventing future infections.

Is cranberry juice or a cranberry capsule better?

The Cochrane authors rated the evidence on juice versus tablets as very low certainty, so it is unclear. NCCIH adds that processing into tablets or capsules can reduce PAC concentration, so look for a stated PAC amount rather than assuming equivalence.

Is d-mannose worth taking for recurrent UTIs?

The 2024 MERIT trial of 2 g a day for 6 months found no significant difference from placebo (51.0% against 55.7% with a medically attended UTI), and its authors advised against recommending it for prophylaxis in that group. A doctor can discuss options that have better support.

Is bearberry safe to take?

A 2013 toxicology review judged a defined therapeutic dose safe under recommended conditions, but that does not cover every capsule or long-term use, and LactMed advises avoiding uva-ursi while breastfeeding. Ask your doctor or pharmacist before using it, especially if pregnant or on other medicines.