Due to a lack of information regarding safety, children, people with kidney disease, pregnant women, and breast-feeding mothers should not take Uva Ursi.
People with high blood pressure should consult a doctor before using Uva Ursi.
Because Uva Ursi requires an alkaline urine for its antimicrobial properties to work, those taking Uva Ursi should avoid eating acidic foods like citrus, pineapple, tomato.
Prescription drugs such as ammonium chloride, non-prescription products such as vitamin C, herbals such as rose hips, and foods such as cranberry juice may all make the urine more acidic in nature.
Potentially, taking a urine acidifier may lessen or destroy the antibacterial effects of Uva Ursi.
Alternatively, urinary alkalizers, drugs such as antacids, Bicitra, K-lyte, Polycitra, and sodium bicarbonate; herbals such as alfalfa and peppermint; and foods such as molasses, raisins, spinach, and some dried beans reduce the acid levels in urine, which may increase Uva Ursi’s antibacterial effects.
Uva Ursi should only be taken for short periods (no longer than a week), and not repeated more than five times in one year.
While some people with sensitive stomachs develop nausea and vomiting with Uva Ursi, the herb appears to be quite safe for most people when taken at commonly recommended doses. However, high doses can cause a disconcerting, although apparently harmless, greenish-brown discoloration of the urine.
Extremely high doses of Uva Ursi, in the range of 10 times greater than the commonly recommended amount, can cause vomiting, ringing in the ears, shortness of breath, convulsions, and collapse in some cases. Liver damage is also a risk with high doses taken over extended periods of time.