Cranberry Extract for UTIs: What the Evidence Says and How to Choose

Think you have a UTI? Get it checked and treated by a clinician. Don't use cranberry in place of proven treatment for an infection (NCCIH).

What is cranberry extract?

The American cranberry (Vaccinium macrocarpon) is an evergreen shrub that grows in boggy, wet ground across the Northeast and upper Midwest of North America (NCCIH). Native peoples and later European settlers used the berries as food, dye and medicine.

Cranberry extract supplements are made from dried, powdered or concentrated fruit or juice. The compounds researchers care most about are proanthocyanidins, or PACs. Cranberry PACs have an unusual "A-type" chemical link that appears to help keep E. coli bacteria from gripping the bladder lining (Howell et al., BMC Infectious Diseases, 2010). The idea is that bacteria that can't hold on have a harder time starting an infection. Processing fruit into pills can lower PAC content, which is one reason products differ (NCCIH).

Does cranberry extract work for UTIs?

For preventing repeat infections in some groups, the evidence is moderately good. For treating an infection you already have, there is no good evidence.

The 2023 Cochrane review (Williams et al.) pooled 50 trials with 8,857 people. Across 26 trials that could be combined, cranberry products cut the risk of a symptomatic, lab-confirmed UTI by about 30 percent compared with placebo or no treatment, with moderate certainty. The results varied by group:

• Women with recurrent UTIs: about 26 percent fewer infections.
• Children: roughly half as many infections.
• People prone to UTIs because of a medical intervention: roughly half as many.
• Little or no benefit: older adults living in care facilities, pregnant women, and people whose bladders don't empty fully because of nerve or muscle conditions.

Compared with preventive antibiotics in two trials, cranberry may make little or no difference to infection risk. In three small trials against probiotics, cranberry may have done better. A companion Cochrane review in 2023 searched for trials of cranberry as a treatment for an active UTI and found none that qualified (Jepson et al.).

NCCIH describes the same picture: a likely drop in repeat UTIs of about a quarter, with some inconsistent results. Since 2020 the FDA has allowed cranberry supplements to carry a qualified claim that "limited" evidence suggests daily use could lower the chance of repeat UTIs in healthy women. Juice drinks must call their evidence "limited and inconsistent."

How to choose a cranberry supplement: PACs and labels

Milligrams of cranberry on a label tell you little on their own. A PAC amount is more useful. In a placebo-controlled study, three different extracts each standardized to 36 mg of PACs, measured by the BL-DMAC method, made volunteers' urine better at keeping E. coli from sticking for 6 to 12 hours after one dose (Howell et al., Natural Product Communications, 2015). In another study, that urine effect grew with dose and lasted up to 24 hours at 72 mg of PACs a day (Howell et al., 2010).

Those are lab tests on urine, not infection counts. When Cochrane compared low, moderate and high PAC doses in actual trials, it couldn't show that one worked better than another. A reasonable approach:

• Prefer products that state PACs per serving and name the test method.
• Follow the label. The FDA's qualified claim is about daily use.
• Check the label for added sugar if you choose a liquid or juice.

Side effects, interactions and who should be careful

Cranberry is generally considered safe by mouth. Very large amounts can cause stomach upset and diarrhea, especially in young children (NCCIH). In Cochrane's trials, stomach side effects were about as common with cranberry as with placebo.

• Warfarin: evidence on an interaction is conflicting (NCCIH). Memorial Sloan Kettering lists case reports of bleeding, including two deaths in older adults who drank cranberry juice with warfarin. If you take warfarin, talk to your prescriber before using cranberry.
• Kidney stones: cranberry contains oxalate, a compound found in the most common type of kidney stone (Memorial Sloan Kettering). In five volunteers, cranberry concentrate tablets raised urine oxalate by an average of 43 percent in a week (Terris et al., Urology, 2001). A liter of juice a day raised calcium oxalate saturation by 18 percent in another study (Gettman et al., Journal of Urology, 2005). If you've had calcium oxalate stones, ask your doctor first.
• Salicylates: drinking 750 mL of cranberry juice a day for two weeks raised salicylic acid in urine and slightly in blood (Duthie et al., 2005). If you've been told to avoid salicylates, mention cranberry to your clinician.
• Other drugs: Memorial Sloan Kettering reports that blood levels of the transplant drug tacrolimus dropped with cranberry extract, and cranberry may change levels of other medicines processed by liver enzymes.
• Pregnancy: food amounts appear safe, but larger amounts aren't well studied, and Cochrane found no clear benefit for UTI prevention in pregnancy.

Find it at William's

We carry cranberry in capsule, tablet and liquid form:

• Nature's Way cranberry fruit, 180 vegan capsules: capsules of cranberry fruit.
• Nature's Way cranberry premium blend, 60 tablets: cranberry fruit solids combined with vitamin C.
• Natural Factors CranRich 500 mg, 90 capsules: a cranberry concentrate with no sugar or artificial sweeteners, taken one to three times a day.
• Nature's Way CranRx liquid cranberry, a 16 fl oz bottle: each serving has 1,000 mg of whole cranberry concentrate standardized to PACs, plus vitamin C, D-mannose and hibiscus extract.

Our product pages don't list PAC amounts for every item, so check the label in store. People exploring urinary support often also ask about uva ursi and probiotics; see those guides for what the evidence shows.

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