Herbs & Supplements

Should I take it?

As a plant, uva ursi generally stays small--only reaching a maximum height of about 2 feet, and often remaining as a ground cover under certain growing conditions. It grows slowly, but it thrives in areas such as canyon walls and rocky seacoasts that are hostile to other types of vegetation. Its small dark green leaves may turn a brownish color in the autumn, but they do not fall off the plant. White or pink flowers that bloom in the summer are followed by clusters of orange or red berries. Although the berries are edible for humans, they are not used much as food due to their somewhat bitter taste. They are said to attract bears, though, which may be why the plant was given the Latin name for "bearberry". Only the green leaves are harvested in the late summer or fall and dried for use in medicine. Native Americans are believed to have used dried uva ursi leaves like tobacco. In some countries, it has been used for tanning leather.

One of the chemical in uva ursi is hydroquinone, which was approved in 1982 by the U.S. Food and Drug Administration (FDA) as a topical agent for lightening freckles and other areas of darkened skin. Based on information from recent studies, however, the FDA has retracted approval and recommended that hydroquinone be removed from the market.

Dosage and Administration

Note: Because it has the potential to cause kidney, liver, or stomach damage, uva ursi should be taken no longer than 5 days at a time. Its oral use should be limited to only a few times a year, as well.

Although dosing for uva ursi varies, a commonly suggested dose range to treat urinary tract infections (UTIs) is 2,000 mg (2 grams) to 4,000 mg (4 grams) per day. Whether the recommended amounts of uva ursi actually reach high enough levels in the urine to be useful for treating UTIs is questionable since the antibacterial action of uva ursi is diminished or cancelled when the urine has a high acid content. Many foods and beverages may make the urine acidic. However, bacteria usually need a low-acid (alkaline) environment, so they release a substance known as urease to lower the acid content of urine.

Tea may be made from uva ursi by soaking up to 3,000 mg (3 grams) of the dried leaves in about 5 ounces of cold water for at least 12 hours to decrease the amount of tannins. After the solid particles are strained out, the tea may be heated or consumed cold up to four times a day. In the past, cool uva ursi tea has also been used as a skin wash to treat mild skin infections.

Summary

The main use of uva ursi--to treat urinary tract infections--has been replaced by newer, more effective, and safer prescription drugs.

Risks

The high tannin content of uva ursi may cause kidney, liver, or stomach damage--especially for individuals who already have medical conditions of the kidney, liver or stomach. Higher rates of certain cancers may be attributed to high or long-term use of products containing tannins. These effects may be more likely for children under the age of 12 years more than they are for adults, so the use of uva ursi is not recommended for children or for breast-feeding women. Pregnant women may suffer a miscarriage, early onset of labor, or rapid delivery if they take uva ursi.

Side Effects

A single dose of 30,000 mg (30 grams) of uva ursi taken at one time has caused death. Single doses of 6,000 mg (6 grams) have been associated with seizures. Long-term use of uva ursi may damage vision permanently. Smaller doses may cause discolored urine, nausea, or ringing in the ears.

Interactions

Drugs or foods that acidify the urine may decrease antibacterial effects of uva ursi, but urinary alkalizers (drugs or foods that reduce urine acid levels) may increase its antibacterial activity. The tannin content in uva ursi might interfere with the absorption of drugs and nutrients from food.

Last Revised August 1, 2008