Cranberry

Bog cranberry, highbush cranberry, marsh apple, mountain cranberry, mooseberry, moss berry, trailing swamp cranberry, Vaccinium macrocarpon

The useful components of cranberry are obtained from the juice of the ripe cranberry fruit. It contains substances called proanthocyanidins that appear to prevent Escherichia coli, a common pathogen in urinary tract infections (UTIs), from adhering to the epithelial cells lining the bladder wall. Cranberry is available as capsules and tablets of concentrated extract, concentrated liquids, syrups, tinctures, juices, and sweetened juices, in products such as Cran-Actin, Cranberry-Plus, Emergen-C Cranberry, and Ultra Cranberry.

Reported uses

Cranberry is used to prevent UTIs, particularly in women prone to recurrent infection. It’s also used to prevent kidney stones and to treat asthma, fever, and active UTI. It’s used as a urine deodorizer in urinary incontinence. Cranberries are also eaten as a food.

Administration

Capsules: 300 to 500 mg by mouth two to three times a day

Cranberry juice, unsweetened: 8 to 16 oz (240 to 480 ml) a day to treat infection

Cranberry tincture: 3 to 5 ml three times a day.

Hazards

Adverse effects associated with the use of cranberry include diarrhea and irritation if large quantities are ingested. Cranberry may decrease the effectiveness of weakly alkaline drugs, such as many antidepressants and prescription painkillers. There are no reported precautions for the use of cranberry at this time.

Clinical considerations

Tinctures may contain up to 45% alcohol. Patients with a history of alcohol abuse or liver disease or those taking metronidazole or disulfiram should be cautioned to avoid use of alcohol-containing preparations.

Contrary to early investigations focusing on cranberry’s ability to acidify the urine, its ability to prevent bacteria from adhering to the bladder wall seems to be more important in preventing UTIs. Only the unsweetened, unprocessed form of cranberry juice is effective.

Cranberry is safe for use in pregnant and breast-feeding patients.

When consumed regularly, cranberry may be effective in reducing the frequency of bacteriuria with pyuria in women with recurrent UTIs.

Advise patient to notify the health care provider if signs or symptoms of a UTI appear. Explain that an appropriate antibiotic is usually needed to treat an active UTI.

If patient has diabetes, inform him that cranberry juice contains sugar but that sugar-free cranberry supplements and juices are available.

Tell patient to remind prescriber and pharmacist of any herbal or dietary supplement that he’s taking when obtaining a new prescription.

Advise patient to consult his health care provider before using an herbal preparation because a treatment with proven efficacy may be available.

Research summary

Most of the research on cranberry to prevent UTIs has been conducted on commercial cranberry beverages, not dried cranberry powder.

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