Bears snack on its fruits, Native Americans smoke it, and women take it for UTIs. Clinical evidence only partly supports traditional uses of uva ursi and brings up some safety concerns. Read on for a breakdown of uva ursi uses, benefits and side effects.
What Is Uva Ursi?
Arctostaphylos uva-ursi is a woody shrub from the Heath family of plants (Ericaceae). Common names for this plant are bearberry, crowberry, kinnikinnick, and pinemat manzanita .
Both “Arctostaphylos” (Greek) and “uva ursi” (Latin) mean bear’s grape; supposedly, bears love snacking on uva ursi fruits. Native to North American mountains, uva ursi prefers higher northern areas of Europe, America, and Asia .
Uva ursi is just one type of bearberry, the other ones being:
- Arctostaphylos adenotricha (found in the Sierra Nevada)
- Arctostaphylos coactilis (located on the costs of California)
- Arctostaphylos cratericola (found in the high mountains of Guatemala)
Uva ursi grows as a short, dense bush, with evergreen leaves lasting for a couple of years. Leaves are thick, shiny, and oval with rounded tips. In late spring, uva ursi blooms tiny white-to-pink flowers. Fruits are bright red glossy berries that last until early winter.
- May prevent UTIs
- Lightens the skin
- May relieve allergies
- Fights bacteria and viruses
- May help reduce blood pressure
- May not treat UTIs
- Not well studied in humans
- Not suitable for long-term consumption
- Some metabolites may be toxic
Traditional and Modern Uses
According to some records, famous Welsh Physicians of Myddfai used uva ursi back in the 13th century. French botanist Carolus Clusius first described it in 1601, and its medicinal use spread to the rest of Europe by the 18th century.
Folks around the globe have been using uva ursi to treat UTIs, inflammation, and stones in the bladder and kidneys, diabetes, and venereal diseases.
Traditional medicine uses creams and lotions with uva ursi (bearberry) for skin lightening. Nowadays, UTIs and skin issues remain the top uses of this herb [3, 4, 5].
Native American people add dried uva ursi leaves to tobacco and other herbs to make a smoking mix or “kinnikinnick.” Swedish and Russian folks use it for skin processing.
Uva ursi found its way to many gardens and urban areas. Its dense bushes and evergreen leaves are attractive and easy to cultivate.
In herbal medicine, only the dried uva ursi leaves have value. Commercial mixtures and loose teas often contain the entire plant, but that indicates poor product quality.
The main active ingredient is arbutin (5 – 12%), a complex sugar-bound molecule. Enzymes in the gut transform arbutin into hydroquinone, responsible for its main medicinal actions. Standardized uva ursi leaf extracts should contain 420 mg or 20% of arbutin [6, 7, 8+].
Uva ursi leaves are also rich in tannins such as corilagin (10 – 20%), which clean and shrink body tissues (tannins in wine and berries shrink your mouth). Other components include [9, 10, 11, 3]:
- Phenolic acids: gallic, p-coumaric and syringic acid
- Flavonoids: catechin, quercetin
- Enzymes: beta-glucosidase (arbutase)
- Triterpenes: ursolic acid, α-amyrin,
- Minerals: iron, selenium, manganese
- Other: allantoin, resin, wax, fatty acids
Autumn is the best season to harvest the leaves and get the peak arbutin content. Experts recommend using wild (indigenous) plants for the best product quality .
Mechanism of Action
According to limited research, arbutin and its metabolite, hydroquinone, may [13, 14, 15, 16]:
- Prevent the growth of bacteria
- Reverse oxidative damage
- Soothe inflammation
- Protect the nerves
They also inhibit tyrosinase, a crucial enzyme that makes the skin pigment melanin [17, 18].
Although the majority of research about uva ursi focuses on those two compounds, corilagin has also shown the above effects. Astringent (shrinking) and antibacterial properties of corilagin may contribute to the impact of uva ursi on UTIs and other infections [19, 20, 21].
Health Benefits of Uva Ursi
No valid clinical evidence supports the use of uva ursi for any of the conditions in this section. Below is a summary of low-quality clinical trials and cell-based research, which should spark further investigation. However, you shouldn’t interpret them as supportive of any health benefit.
1) Urinary Tract Infections (UTIs)
Each year, approximately 150 million people suffer from urinary tract infections (UTIs). The resistance of bacteria that cause UTIs, such as E. coli and E. faecalis, to common antibiotics poses huge challenges and makes research about complementary approaches like uva ursi important .
In a clinical trial of 57 women with frequent UTIs, uva ursi prevented bladder inflammation. After a one-month treatment (540 mg/day of the dry extract), the women were free of symptoms for one year and reported no side effects .
- Coli and other UTI-causing bacteria couldn’t survive in the urine samples of patients who took uva ursi extract or arbutin (100 – 1,000 mg) [24+, 25].
Hydroquinone, the primary metabolite of arbutin, is more efficient against bacteria in alkaline urine (pH ~ 8). Baking soda (6 – 8 g) may alkalize urine and boost the antibacterial action of uva ursi [21, 4, 25].
That said, uva ursi failed to cure UTIs in a much larger clinical study (382 women). By the 4th day of infection, patients reported no difference in symptoms and antibiotic use .
A review of clinical data and traditional uses also questioned the ability of uva ursi (bearberry) to treat UTIs. The authors suggested it for short-term prevention and emphasized the need for large well-designed trials. A team of German doctors has already announced one [4, 26].
Cell experiments have also suggested the antibacterial action of uva ursi extract against the most common causes of UTI, such as E. Coli, S. saprophyticus, and E. faecalis [26, 27, 3].
Corilagin and other tannins from uva ursi leaves may decrease inflammation, tighten the urinary tract walls, and help combat UTI-causing bacteria [19, 28].
Animal and Cellular Research (Lacking Evidence)
No clinical evidence supports the use of uva ursi for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies listed below should not be interpreted as supportive of any health benefit.
2) Other Urinary Tract Issues
In a study on rats, researchers observed the ability of uva ursi extract to dissolve kidney stones and clean the urinary tract. Once again, the authors pointed to the role of alkaline pH in these effects .
Enhanced urination (diuretic effect) is one of the body’s mechanisms to get rid of bacteria in the urinary system. Herbs and substances with this action may also help with UTIs and prevent kidney stone build-up .
Uva ursi was able to increase urine flow in rats while maintaining the electrolyte balance .
3) Inflammation and Allergies
In studies on mice with allergies, uva ursi extract and arbutin were able to [14, 32, 33]:
- Sooth the animals’ skin
- Decrease inflammation and swelling
- Relieve allergic reactions
- Support standard treatment with NSAIDs and corticosteroids
A cream with uva ursi extract (1 – 2%) showed similar results when applied to animals’ skin. It couldn’t decrease swelling on its own, but it boosted the effects of a corticosteroid cream .
4) Microbial Infections
Antibacterial effects of uva ursi (bearberry) aren’t limited to urinary tract infections. In a cell study, uva ursi extract reduced the growth of MRSA – a dangerous type of bacteria (S. aureus) resistant to common antibiotics. When combined with antibiotics, uva ursi boosted their potency 100 – 2,000 times .
Corilagin found in uva ursi leaves may inhibit the growth of Helicobacter Pylori, which causes stomach ulcers .
According to cellular studies, corilagin may prevent the spreading of the HIV-1 virus by blocking its 2 essential enzymes – protease and reverse transcriptase. Corilagin was effective even against the drug-resistant HIV strains, making it a promising herbal add-on. However, clinical studies are needed to investigate its anti-HIV effects in the human body [37, 38].
5) High Blood Pressure
One of the major components of uva ursi leaves, corilagin, was able to reduce high blood pressure in rats. It blocked the release of noradrenaline and relaxed blood vessels [39, 40, 41].
Many drugs for high blood pressure work by stimulating urination (diuretics). Uva ursi extract showed this effect in rats, but its effects on blood pressure haven’t been researched yet .
6) Liver Protection
In animal studies, researchers noticed the potential of corilagin, which is abundant in uva ursi leaves, to protect the liver against [42, 43, 44, 28, 45, 46]:
- Parasitic infections
- Potentially toxic drugs (Tylenol)
- Bleeding caused by injuries
- Impaired bile acid flow
However, whole uva ursi herb or extract may not have the same effects as isolated components. No studies have observed the liver-protective effects of uva ursi.
Limitations and Caveats
- Clinical data on the benefits of uva ursi for UTIs is minimal and conflicting.
- It has shown other medical properties in animal and cell studies only.
- Many studies used isolated components, not the extract.
Only one clinical trial showed the benefits of uva ursi for UTI prevention. We may question its results due to a small sample size and the possible contribution of dandelion extract .
Skin Benefits of Uva Ursi
Cosmetic products with uva ursi extract and its chief components, arbutin and hydroquinone, have a long history of use for skin lightening and spot removal [3, 5].
A review of 30 clinical trials proclaimed arbutin an efficient depigmenting (lightening) agent .
The same goes for ts metabolite, hydroquinone, but, due to safety concerns, some health experts suggest limiting its use to hair dyes and nail care products [48, 49, 50, 51].
In test tubes, uva ursi leaves, arbutin, and hydroquinone inhibited the production of melanin [52, 17, 18].
Uva ursi extract may not have the same effects in cosmetic products as arbutin or hydroquinone. Clinical trials should examine its skin-lightening potential.
Uva Ursi Side Effects & Precautions
This list does not cover all possible side effects. Contact your doctor or pharmacist if you notice any other side effects. In the US, you may report side effects to the FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada, you may report side effects to Health Canada at 1-866-234-2345.
In clinical trials, uva ursi leaf extract and its chief component, arbutin, didn’t cause any notable side effects [8, 23, 25].
Long-term observations have also suggested a decent safety of uva ursi leaves. Doctors reported a single case of retina (eye tissue) damage in a woman who used uva ursi for three years [3, 53].
In our body, arbutin turns into hydroquinone, which has caused some safety concerns. In some animal studies, it increased the risk of kidney cancer. However, this effect was limited to one strain of older male rats and had no human consequences [54, 18].
Injecting hydroquinone damaged bone marrow of some lab animals, but oral consumption did not. A review of safety studies suggested that hydroquinone is safe for humans in the amounts present in uva ursi leaves [55, 6].
Due to some signs of long-term hydroquinone toxicity, experts recommend limiting uva ursi treatment to 1 week and up to 5 times per year [21, 3].
Children under 12 years and pregnant women should avoid it [3, 56, 57].
Safety in Cosmetics
In clinical trials, patients reported no side effects after using a cream with hydroquinone (2 – 4%) for up to 3 months. Skin toxicity studies also voice its safety, but one review suggested limiting its use to hair dyes and nail care products [50, 58, 54, 51].
According to the Scientific Committee on Consumer Safety (SCCS), arbutin in cosmetic products is safe in concentrations up to 0.5% (body lotions) and 2% (face creams) .
Herb-drug interactions can be dangerous and, in rare cases, even life-threatening. Always consult your doctor before supplementing and let them know about all drugs and supplements you are using or considering.
Uva ursi extract may inhibit CYP enzymes, which metabolize different drugs and chemicals in the body. The following medicines may thus interact with uva ursi [60, 61]:
- Statins (high-cholesterol drugs)
- SSRIs (antidepressants)
- Azoles (antifungal drugs)
- Some antibiotics and antiviral drugs
Drugs and herbs that enhance urination (diuretics) – including uva ursi leaves – may provoke the side effects of lithium, used for bipolar disorder. Due to its diuretic action, uva ursi may enhance the effects of drugs for high blood pressure [62, 31].
Uva Ursi Dosage & Supplements
Uva ursi supplements have not been approved by the FDA for medical use. In general, regulatory bodies aren’t assuring the quality, safety, and efficacy of supplements. Speak with your doctor before supplementing.
Pills with dry uva ursi (bearberry) leaf extract are the most common form of supplementation. Some products are standardized to 20% arbutin. Uva ursi is also available as:
- Loose tea (dried leaves)
- Tea bags
- Liquid extract (tincture)
Uva ursi is also popular in cosmetics. Different skin-lightening serums and creams contain uva ursi leaf extract and its main components – arbutin and hydroquinone.
The below doses may not apply to you personally. If your doctor suggests using a grape seed extract supplement, work with them to find the optimal dosage according to your health condition and other factors.
In clinical trials, doses ranged from 400-1,000 mg of arbutin, which equals 2-5 g of a standardized uva ursi leaf extract (20% of arbutin) [8+, 23+, 6, 25+].
For other forms, experts recommend the following doses [21+, 3+]:
- Infusion (tea): 3 g of dried leaves in 150 ml of water, 3 – 4 times per day for 1 week
- Powdered leaves: up to 1,750 mg/day, divided into 2 – 3 doses
- Liquid extract (tincture): 1.5-4 ml/day (max. 8 ml/day)
Combinations With Other Herbs
In a successful clinical trial (UTI prevention), women took a supplement with uva ursi leaf and dandelion root extracts .
People often combine uva ursi with other herbs that stimulate urination, relieve inflammation, and help combat UTIs. Corn silk, nettle and parsley leaves, horsetail, and marshmallow root are frequent in those mixtures. However, studies haven’t tested the safety and efficacy of these combinations.
Cranberry juice (or extract) is a popular natural remedy for UTIs, but you shouldn’t combine it with uva ursi leaves. It makes urine acidic, potentially weakening the antibacterial effects of uva ursi .
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Users mostly take pills with uva ursi leaf extract to treat or prevent UTIs. The majority of them reported positive results and no side effects. Some users experienced no benefits, with a few cases of nausea and headache.
People also use lightening serums and creams with uva ursi extract or arbutin to remove dark spots and soften the skin. They have reported mix results.
Arctostaphylos uva-ursi is the most popular type of bearberry, used in traditional medicine to treat urinary tract issues, diabetes, inflammation, and skin spots. Only the leaves have medicinal value; they contain arbutin and corilagin with antimicrobial, anti-inflammatory, and antioxidant properties.
Clinical trials haven’t confirmed the ability of uva ursi to treat UTIs, but it may prevent them. It’s potential to help with kidney stones, allergies, and high blood pressure was tested in animal and cell-based studies only.
Cosmetic products with uva ursi extract or its components can lighten the hair and skin. You may want to avoid skin products with isolated hydroquinone.
Clinical trials revealed no significant side effects of uva ursi leaves or extract. Due to some safety concerns, experts recommend limiting their use to one week, up to five times per year. Pregnant women and children under 12 years should avoid uva ursi, while others should consult with their doctor before supplementing.