Cranberry Extract

Supplements · Immune & Antimicrobial Herbs · Supplement, Typed Supps

A tart red berry with real, Cochrane-reviewed evidence for preventing recurrent UTIs — as long as the product actually contains enough of its active compound.

Stage by stage

Intake (Capsule or concentrated juice): Taken orally, once or twice daily.
Small intestine (Absorbed): Proanthocyanidins (PACs) absorbed alongside digestion.
Bloodstream (Circulates): Carried systemically toward the urinary tract.
Bladder (Uroepithelium): PACs inhibit E. coli adhesion to the bladder wall, reducing recurrent infection risk.

What the evidence supports

Reducing recurrent UTI risk in women prone to them — moderate evidence. A 2023 Cochrane review of 50 trials (nearly 8,900 participants) found cranberry products reduced symptomatic, culture-verified UTIs in women with recurrent UTIs, in children, and in people susceptible after certain procedures. The benefit appears concentrated in products delivering at least about 36mg/day of proanthocyanidins (PACs); a 2024 dose-response meta-analysis found an 18% risk reduction at or above that threshold, and no significant effect below it.
Treating an existing, active UTI — insufficient evidence. Cranberry has not been shown to treat an existing infection. Its evidence base is specifically for prevention, and it should not replace antibiotics for a diagnosed UTI.
Benefit from low-PAC or short-duration (under 12 weeks) use — limited evidence. Meta-analyses suggest the effect requires both a meaningful PAC dose (≥36mg/day) and roughly 12–24 weeks of sustained use; many commercial cranberry juices and low-dose capsules don't clearly meet either threshold.

Typical dose

Products standardized to at least 36mg proanthocyanidins (PAC) per day, taken for 12–24 weeks in studied protocols

Upper limit: No established UL

Timing

No specific food requirement; daily consistency over months matters most.

Time to effect

12–24 weeks: The clearest reduction in recurrent UTI risk in trials was seen with sustained daily use over roughly twelve to twenty-four weeks, not a single dose after symptoms start.

Common myth

“Drinking cranberry juice will treat a UTI you already have.” In reality: The evidence supports prevention with a sustained, adequately dosed PAC intake over months — not treatment of an active infection, and not the dilute, sugary juice cocktail most people picture.