Cranberry Extract (PAC-standardised) and medications.
Cranberry Extract (PAC-standardised) is classified as a targeted supplement in the Distil database, evidence Grade B. The page below lists every medication we have explicitly assessed it against.
Cranberry extract standardised for proanthocyanidins is taken to prevent recurrent urinary tract infections. The PACs stop P-fimbriated E. coli from sticking to the bladder wall, so the mechanism is anti-adhesive rather than antimicrobial. Evidence is Grade B for recurrent UTIs in women and for intervention-related UTIs after catheterisation, with around a quarter to a half reduction in recurrence depending on the group. Dose is the catch: you need at least 36mg of PACs a day, sustained for three to six months, and most over-the-counter capsules and gummies fall well below that and simply do not work. Choose a PAC-standardised tablet or capsule, not juice, which carries a heavy sugar load. Benefit was not shown in institutionalised elderly adults or in neuromuscular bladder dysfunction. On interactions, monitor INR if combined with warfarin, and avoid high-volume juice. Exclude it in pregnancy, where trials showed no benefit, and in anyone with a calcium oxalate kidney stone history, since cranberry raises urinary oxalate.
Below are the 2 documented pairs we have explicitly assessed for Cranberry Extract (PAC-standardised): 2 amber. The pairs cluster around 1 mechanism: Additive anticoagulation. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not listed here is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by medication, and the missing-item form at the bottom of the page routes any uncatalogued medication into our next curation pass.
Documented interactions
Last reviewed 14 June 2026. Each interaction below is assessed against PubMed-indexed evidence.
Additive anticoagulation
Amber Does interact with Acenocoumarol?
Cranberry, mainly as large volumes of juice, can occasionally raise the effect of acenocoumarol, a vitamin-K-based blood thinner in the same family as warfarin, and push your INR up. The signal comes from the related drug warfarin rather than from acenocoumarol directly. If you take acenocoumarol, keep your cranberry intake steady rather than starting or stopping it suddenly, and tell your anticoagulant clinic so your INR can be watched.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does interact with Warfarin sodium?
Cranberry can occasionally push warfarin's blood-thinning effect higher, mainly when taken as large volumes of cranberry juice. Standardised cranberry extract at studied doses appears safer than high-volume juice, but tell your GP either way and ask whether INR monitoring should be a little tighter for the first few weeks.
Evidence: Supported by human study data.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope. Use the checker below to surface any medication, and submit a missing item if you take something we have not catalogued.
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