Avoid in individuals with a known allergy or hypersensitivity to Arctostaphylos uva-ursi or its constituents.
Side Effects and Warnings
Uva ursi is generally well tolerated in short-term, traditional doses, but available human trial data is limited. Uva ursi may cause tachycardia (fast heartbeat), cardiac arrhythmias (abnormal heart rate), skin irritations, nausea, vomiting, diarrhea, stomach upset, greenish-brown urine color, irritation and inflammation of the urinary tract mucous membranes, hepatotoxicity (liver damaging), insomnia, convulsions, seizures, irritability, motor restlessness, cyanosis (bluish skin discoloration due to lack of oxygen in the blood), headaches, shortness of breath, or tinnitus (ringing in the ears).
Long-term ingestion of uva ursi has caused bilateral bull's-eye maculopathy, and may be considered a potential retinal toxic herb. Use cautiously in patients with renal (kidney) or hepatic (liver) dysfunction, due to risk of inflammation of the urinary tract and hepatoxicity. Avoid in patients with kidney disease. Use cautiously in patients with gastrointestinal distress because the preparation can be irritating to the mucous membrane of the stomach and the intestine due to high amounts of tannins. Use cautiously in patients taking diuretics, which may promote electrolyte imbalance. Use cautiously in patients suffering from gallstones.
Pregnancy and Breastfeeding
Uva ursi is not recommended in pregnant or breastfeeding women due to a lack of sufficient available evidence. Large amounts of uva ursi may induce labor.
Adults (18 years and older):
There is no proven safe or effective dose for uva ursi. Cystinol akut® is one brand that has been studied. A typical dose taken by mouth is 3 grams of uva ursi (or 400-800 milligrams of hydroquinone derivatives) steeped in water and taken as a tea, or taken in powder form, four times a day for inflammatory conditions. For urinary tract infection (UTI), 250-500 milligrams of uva ursi powdered extract (20% arbutin) has been taken three times a day (for no more than four days). When applied on the skin, a 2% or 5% hydroquinone cream has been used for hyperpigmentation. A topical preparation containing 3% arbutin (glycoside in uva ursi) over a 12-week period has also been used.
Children (younger than 18 years):
There is no proven safe or effective dose of uva ursi in children, and use is not recommended.
Interactions with Drugs
Uva ursi may increase the inhibitory effect of prednisolone on swelling. The arbutin in uva ursi may potentiate the effects of prednisolone and dexamethasone on contact dermatitis. Caution is advised when using uva ursi with corticosteroids (steroids).
Uva ursi may increase urine flow, and may interact with other agents that increase urine flow (diuretics).
The arbutin in uva ursi may increase the anti-inflammatory activity of indomethacin on contact dermatitis, hypersensitivity, and arthritis. Caution is advised when taking uva ursi with non-steroidal anti-inflammatory drugs (NSAIDs) due to theoretical interactions.
Concomitant use of uva ursi and urine acidifiers may result in decreasing the effects of uva ursi.
Concomitant use of uva ursi and products that can alkalinize the urine can enhance the antibacterial activity of uva ursi.
Interactions with Herbs and Dietary Supplements
Combination of uva ursi and aloesin inhibits tyrosinase activity in a synergistic manner by combined mechanisms of noncompetitive and competitive inhibitions.
Herbs containing arbutin, a constituent of uva ursi, may result in increases in serum and urinary levels of hydroquinone and its metabolites. Arbutin is found in sweet marjoram, damiana, and other herbs.
Uva ursi may increase urine flow, and interact with other herbs and supplements with diuretic effects.
Concomitant use of uva ursi and products that can acidify the urine (e.g., vitamin C) can potentially reduce the antibacterial activity of uva ursi.
Concomitant use of uva ursi and products that can alkalinize the urine may enhance the antibacterial activity of uva ursi.