Merck Manual

Please confirm that you are a health care professional

honeypot link

Cranberry

By

Laura Shane-McWhorter

, PharmD, University of Utah College of Pharmacy

Reviewed/Revised Jan 2023
View PATIENT EDUCATION

Cranberries are fruit that can be consumed whole or made into food products such as jellies and juices.

Claims

People most often take cranberries to help prevent and relieve the symptoms of urinary tract infections Introduction to Urinary Tract Infections (UTIs) Urinary tract infections (UTIs) can be divided into upper and lower tract infections: Upper tract infections involve the kidneys ( pyelonephritis). Lower tract infections involve the bladder... read more (UTIs). The effectiveness of cranberries in preventing UTIs has not been confirmed. Natural unprocessed cranberry juice contains anthocyanidins (eg, proanthocyanidin), which prevent Escherichia coli from attaching to the urinary tract wall.

Some people take cranberry juice to reduce fever and treat certain cancers; however, there is no scientific proof that it is effective for these uses.

Evidence

The US Food and Drug Administration (FDA) has stated that it authorized (allowed) qualified health claims for a reduced risk of recurrent UTIs in healthy women (see FDA Announces Qualified Health Claim for Certain Cranberry Products and Urinary Tract Infections).

In 1966, the first clinical trial, uncontrolled, evaluating the positive effects of cranberry juice in preventing UTIs was published (1 References Cranberries are fruit that can be consumed whole or made into food products such as jellies and juices. (See also Overview of Dietary Supplements and National Institutes of Health (NIH): Cranberry... read more ). Since that time numerous trials have been performed evaluating different populations, severity of medical conditions, dosages, time, and form of supplement in juice or extract capsule/tablet.

The majority of evidence suggests that cranberry juice or extract can have a small, yet significant effect on preventing the recurrence of UTIs over 12 months, but that supplementation cannot treat UTIs (2 References Cranberries are fruit that can be consumed whole or made into food products such as jellies and juices. (See also Overview of Dietary Supplements and National Institutes of Health (NIH): Cranberry... read more ). However, a 2012 Cochrane review of 24 studies (4473 participants) placed some doubt on the effectiveness of the supplement, indicating a small trend toward fewer UTIs with supplementation, but that the finding was not statistically significant (3 References Cranberries are fruit that can be consumed whole or made into food products such as jellies and juices. (See also Overview of Dietary Supplements and National Institutes of Health (NIH): Cranberry... read more ). A 2017 meta-analysis of 28 studies (4947 participants) found that UTIs are decreased significantly by 33% (4 References Cranberries are fruit that can be consumed whole or made into food products such as jellies and juices. (See also Overview of Dietary Supplements and National Institutes of Health (NIH): Cranberry... read more ). A different meta-analysis of randomized controlled trials in women at risk for UTIs also found that cranberry reduced UTI risk by 26% (5 References Cranberries are fruit that can be consumed whole or made into food products such as jellies and juices. (See also Overview of Dietary Supplements and National Institutes of Health (NIH): Cranberry... read more ).

Standardization of cranberry products and specifying proanthocyanidin (PAC) content may help to clarify results and resolve the discrepancy. Physiologic differences in the urinary tract and proper hygiene of female individuals studied also could contribute to the variability in response. Due to concern for antibiotic resistance, the American Urological Association 2019 guidelines in women with recurrent UTIs has stated that clinicians may offer cranberry prophylaxis, although this is a Grade C evidence level recommendation (6 References Cranberries are fruit that can be consumed whole or made into food products such as jellies and juices. (See also Overview of Dietary Supplements and National Institutes of Health (NIH): Cranberry... read more ).

Adverse Effects

No adverse effects are known. However, because most cranberry juice is highly sweetened to offset its tart taste, people with diabetes should not consume cranberry juice unless it is artificially sweetened. Because cranberry increases urinary acidity, it may promote stone formation in patients with uric acid kidney stones.

Drug Interactions

Cranberry products may increase the effects of warfarin. Cranberry may increase the effect of the statin atorvastatin and the antihypertensive nifedipine.

References

  • 1. Papas PN, Brusch CA, Ceresia GC: Cranberry juice in the treatment of urinary tract infections. Southwest Med 47(1):17-20, 1966. PMID: 5900988

  • 2. Jepson RG, Craig JC: A systematic review of the evidence for cranberries and blueberries in urinary tract infection prevention. Mol Nutr Food Res 51(6): 738-745, 2007. doi: 10.1002/mnfr.200600275

  • 3. Jepson RG, Williams G, Craig JC: Cranberries for preventing urinary tract infections. Cochrane Database Syst Rev 10:CD001321, 2012. doi: 10.1002/14651858.CD001321.pub5

  • 4. Luís Â, Domingues F, Pereira L: Can cranberries contribute to reduce the incidence of urinary tract infections? A systematic review with meta-analysis and trial sequential analysis of clinical trials. J Urol 198(3):614-621, 2017. doi: 10.1016/j.juro.2017.03.078

  • 5. Fu Z, Liska D, Talan D, et al: Cranberry reduces the risk of urinary tract infection recurrence in otherwise healthy women: a systematic review and meta-analysis. J Nutr 147(12):2282-2288, 2017. doi: 10.3945/jn.117.254961

  • 6. Anger J, Lee U, Ackerman AL, et al: Recurrent uncomplicated urinary tract infections in women; AUA/CUA/SUFU guideline. J Urol 202(2):282-289, 2019. doi: 10.1097/JU.0000000000000296

More Information

The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

Drugs Mentioned In This Article

Drug Name Select Trade
AZO Cranberry, Cranberry, Ellura, TheraCran , TheraCran HP, TheraCran HP for Kids, TheraCran One
Coumadin, Jantoven
Atorvaliq, Lipitor
Adalat, Adalat CC, Afeditab CR, Nifediac CC, Nifedical XL, Procardia, Procardia XL
View PATIENT EDUCATION
NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
quiz link

Test your knowledge

Take a Quiz! 
iOS ANDROID
iOS ANDROID
iOS ANDROID
TOP