Cranberry (Vaccinium macrocarpon) has been used traditionally since the 17th century to treat a variety of ailments, and from the early 1920s to the present as an herbal treatment for recurring urinary tract infections (UTIs). While much of the initial evidence for the antibacterial properties of cranberry has not been proven, the herb's effectiveness against UTIs is unquestioned and the popularity of cranberry juice for this purpose has soared. Recent scientific studies have shown that cranberry prevents E. coli, the most common cause of UTIs, from adhering to the cells lining the wall of the bladder, thus preventing the bacteria from causing a UTI.

Found in North America and grown in bogs, cranberry is an evergreen shrub that is botanically related to blueberry, buckberry, huckleberry, cowberry, and bilberry. The cranberry bush has upright branches whose leaves are speckled on the underside by tiny dots. Pink flowers blossom and red-black fruits appear during June and July.

The ripe fruit of the cranberry is used in commercial and medicinal preparations.

Cranberry is used to treat and prevent urinary tract infections of the bladder and urethra (the tube that drains urine from the bladder).

Cranberry is available as juice, fresh or frozen berries, cranberry concentrate, fresh berries, dried capsules, and tablets.

The following are recommended doses:

• Juice (containing one-third pure juice): 3 or more fluid ounces per day
• Dried capsules: 6 capsules (equivalent to 3 fluid ounces of cranberry juice cocktail)
• Fresh or frozen cranberries: 1.5 ounces (equivalent to 3 fluid ounces of cranberry juice cocktail)

There are no side effects or precautions reported. Keep in mind that cranberry should not be used as a substitute for antibiotics during a serious urinary tract infection.

No noteworthy interactions (positive or negative) between cranberry and conventional medications are known to have been reported in the literature to date.

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