Herb & supplement monograph

Cranberry Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Cranberry interacts with medications. The heart of this page is the interaction list — every drug Cranberry is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Cranberry is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

Check Cranberry against your medication

Add one medication

✓ Supplement

Cranberry

1 Your medication

Start typing any prescription or over-the-counter drug name.

Reviewed by licensed pharmacists Sourced from Natural Medicines

On this page

Cranberry Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Cranberry drug interaction appears low for most people. None of the listed interactions are rated major, and even the moderate ones rest mostly on theoretical or lab-based evidence rather than confirmed effects in people.

Interactions deserving the most attention

The interaction that deserves the most attention involves warfarin, a blood thinner with a narrow safety margin; the research is conflicting, but case reports have linked cranberry juice to a stronger blood-thinning effect and serious bleeding. There is also a single case report of muscle breakdown and abnormal liver tests in a person combining cranberry juice with atorvastatin, possibly because cranberry may slow an enzyme the body uses to clear that drug and many others. An animal study suggests a similar effect with the blood pressure medicine nifedipine, though this has not been seen in humans.

What the rest of the list means

The long list of interacting medications does not mean each combination is harmful. Most entries come from cranberry's possible effect on enzymes that process many drugs, a concern based largely on lab research. In fact, human studies of medicines like diclofenac found no meaningful change, showing several predicted effects simply do not occur in people.

Check your medications against Cranberry

Based on HelloPharmacist’s Cranberry interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Cranberry

714 medications have a known interaction with Cranberry, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Cranberry using our pharmacist-reviewed interaction data.

AI summaries are generated from our Cranberry interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Cranberry combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Cranberry affects

Every type of medication (drug category) Cranberry is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 6 drug categories Cranberry interacts with

Atorvastatin (lipitor)Cytochrome P450 3a4 (cyp3a4) SubstratesNifedipine (procardia)Warfarin (coumadin)Cytochrome P450 2c9 (cyp2c9) SubstratesDiclofenac (voltaren, Others)

Atorvastatin (Lipitor)

Theoretically, cranberry might increase levels and adverse effects of atorvastatin.
In one case report, a patient taking atorvastatin experienced upper back pain, rhabdomyolysis, and abnormal liver function after drinking cranberry juice 16 ounces daily for 2 weeks. Theoretically, this may have been caused by inhibition of cytochrome P450 3A4 (CYP3A4) enzymes by cranberry juice, as atorvastatin is a CYP3A4 substrate. Creatinine kinase and liver enzymes normalized within 2 weeks of stopping cranberry juice. Patients taking atorvastatin should avoid large quantities of cranberry juice.

Likelihood Possible Evidence D

Cytochrome P450 3A4 (Cyp3A4) Substrates

Theoretically, cranberry might increase the levels and adverse effects of CYP3A4 substrates.
A case of upper back pain, rhabdomyolysis, and abnormal liver function has been reported for a patient taking atorvastatin, a CYP3A4 substrate, in combination with cranberry juice 16 ounces daily for 2 weeks. Creatinine kinase and liver enzymes normalized within 2 weeks of stopping cranberry juice. Also, animal research suggests that cranberry juice, administered intraduodenally 30 minutes prior to nifedipine, a CYP3A4 substrate, inhibits nifedipine metabolism and increases the area under the concentration-time curve by 1.6-fold compared to control.

Likelihood Possible Evidence D

Nifedipine (Procardia)

Theoretically, cranberry might increase the levels and adverse effects of nifedipine.
Animal research suggests that cranberry juice, administered intraduodenally 30 minutes prior to nifedipine treatment, inhibits nifedipine metabolism and increases the area under the concentration-time curve by 1.6-fold compared to control. This interaction has not been reported in humans.

Likelihood Possible Evidence D

Warfarin (Coumadin)

Theoretically, cranberry might increase the levels and adverse effects of warfarin. However, research is conflicting.
There is contradictory evidence about the effect of cranberry juice on warfarin. Case reports have linked cranberry juice consumption to increases in the international normalized ratio (INR) in patients taking warfarin, resulting in severe spontaneous bleeding and excessive postoperative bleeding. Daily consumption of cranberry sauce for one week has also been linked to an increase in INR in one case report. In a small study in healthy young males, taking a high dose of 3 grams of cranberry juice concentrate capsules, equivalent to 57 grams of fruit daily, for 2 weeks produced a 30% increase in the area under the INR-time curve after a single 25-mg dose of warfarin. However, 3 very small clinical studies in patients stabilized on warfarin reported that cranberry juice 250 mL once or twice daily for 7 days (27% cranberry juice or pure cranberry juice) or 240 mL once daily for 14 days does not significantly increase INR or affect plasma warfarin levels. The reasons for these discrepant findings are unclear. It is possible that the form and dose of cranberry may play a role, as cranberry extracts and juices contain different constituents. Additionally, an in vitro study evaluating 5 different cranberry juices found varying effects, with only a cranberry concentrate, and not diluted cranberry juices, inhibiting CYP2C9. However, this concentrate did not inhibit CYP2C9 activity in humans.

Likelihood Possible Evidence B

Cytochrome P450 2C9 (Cyp2C9) Substrates

Theoretically, cranberry might increase the levels and adverse effects of CYP2C9 substrates. However, research is conflicting.
There is contradictory evidence about the effect of cranberry on CYP2C9 enzymes. In vitro evidence suggests that flavonoids in cranberry inhibit CYP2C9 enzymes. However, clinical research shows that cranberry juice does not significantly affect the levels, metabolism, or elimination of the CYP2C9 substrates flurbiprofen or diclofenac. Also, in patients stabilized on warfarin, drinking cranberry juice 250 mL daily for 7 days does not significantly increase the anticoagulant activity of warfarin, a CYP2C9 substrate. Additional pharmacokinetic research shows that cranberry juice does not increase peak plasma concentrations or area under the concentration-time curve of warfarin.

Likelihood Unlikely Evidence B

Diclofenac (Voltaren, Others)

Theoretically, cranberry might modestly increase the levels and adverse effects of diclofenac.
In vitro evidence suggests that cranberry juice inhibits diclofenac metabolism by human liver microsomes. However, drinking cranberry juice does not seem to affect diclofenac metabolism in humans.

Likelihood Unlikely Evidence B

Monograph

Cranberry: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

Cranberry is best known for helping to prevent repeated urinary tract infections (UTIs) in some people, and the evidence here is moderate but mixed. It is not a reliable treatment for an active UTI, which usually needs antibiotics. For most people cranberry products are well tolerated, but check with a pharmacist before relying on them, especially if you have frequent infections.

Scientific name: Vaccinium macrocarpon
Family: Ericaceae
Part used: Fruit (berry) and fruit juice
Common forms: Capsules, tablets, softgels, powder, juice, dried berries, liquid extract

People commonly use it for

Urinary tract infection prevention
Bladder health
Antioxidant support
Source of vitamin C

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

Generally well tolerated as a food or supplement, but it is not a substitute for medical treatment of infections.

PregnancyLikely Safe

When consumed in amounts commonly found in the diet. There is insufficient reliable information available about the safety of cranberry when used ther...

Read the full pregnancy detail

BreastfeedingLikely Safe

When consumed in amounts commonly found in the diet. There is insufficient reliable information available about the safety of cranberry when used ther...

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Cranberry is a small, tart red berry that grows on a low, trailing evergreen shrub native to North America. The most studied type is the American cranberry, Vaccinium macrocarpon. The berries are harvested in wet bogs and are used as food, juice, and dietary supplements.

People take cranberry as juice, dried fruit, or in concentrated capsules and tablets. The supplements usually contain dried cranberry powder or extract. Cranberry is most popular for supporting urinary tract and bladder health, and it is also valued as a source of vitamin C and plant antioxidants.

How it works

Cranberries contain plant compounds called proanthocyanidins (PACs), especially A-type PACs. Laboratory research suggests these compounds may make it harder for certain bacteria, such as E. coli, to stick to the lining of the urinary tract. If bacteria cannot attach, they may be flushed out more easily.

Cranberries also supply other antioxidants like flavonoids and vitamin C, which may help protect cells from damage. It is worth remembering that much of this is based on laboratory and test-tube studies, and effects seen in the lab do not always translate into clear benefits in people.

Effectiveness

Does Cranberry work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 25 uses evaluated

1 Possibly effective 24 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

Possibly Effective Urinary tract infections (UTIs)