Bearberry

What Is Bearberry?

Bearberry is a low, trailing evergreen shrub of the heath family whose leaves are a traditional remedy for bladder and urinary tract infections. It is also known as uva-ursi and kinnikinnick.

Bearberry grows around the northern hemisphere, on dunes, rocky slopes and open forest floors. It is the most widespread of the manzanitas and the only one that grows outside North America ^{36Reference 36Parker et al. · 2009Arctostaphylos uva-ursi (Linnaeus) Sprengel — species description, habitat and distribution; genus description — floraView study →}. Europeans have used the leaf as an antiseptic since the 1200s, and Native American peoples smoked it and used it for urinary complaints ^{33,37Reference 33Bone K · 2013Principles and Practice of PhytotherapyReference 37Crane · 1991Arctostaphylos uva-ursi, kinnikinnick — distribution, botanical and ecological characteristics, fire response and uses — species databaseView study →}.

The leaf’s main constituent is arbutin. In the body arbutin is turned into hydroquinone, which is excreted in the urine ^{3,4Reference 3Schindler et al. · 2002RCTUrinary excretion and metabolism of arbutin after oral administration of Arctostaphylos uvae ursi extract in healthy humans — a randomised crossover pharmacokinetic studyView study →Reference 4Quintus et al. · 2005Urinary excretion of arbutin metabolites after oral administration of bearberry leaf extracts — pharmacokinetic studyView study →}. Two trials have tested the leaf in women with uncomplicated urinary tract infections ^{1,2Reference 1Gágyor et al. · 2021RCTHerbal treatment with uva ursi extract versus fosfomycin in women with uncomplicated urinary tract infection in primary care — a double-blind randomised controlled trial (RCT)View study →Reference 2Moore et al. · 2019RCTUva-ursi extract and ibuprofen as alternative treatments for uncomplicated urinary tract infection in women (ATAFUTI) — a factorial randomised trial (RCT)View study →}.

A related species, Arctostaphylos pungens, looks similar, contains less arbutin, and has been sold as bearberry leaf ^{26Reference 26Panusa et al. · 2015UHPLC-PDA-ESI-TOF/MS metabolic profiling of Arctostaphylos pungens and A. uva-ursi — a comparative study of leaf phenolics (species-adulteration relevance)View study →}.

How Is Bearberry Used?

Bearberry leaf is taken for short courses for urinary tract infections and inflammation of the urinary tract, including cystitis and urethritis.

• Cold infusion — the dried leaf steeped in cold water, which extracts less tannin than hot water.
• Tincture or liquid extract — the usual forms in Western herbal practice.
• Standardised dry extract — tablets dosed by their arbutin content, the form used in the clinical trials ^{1,2Reference 1Gágyor et al. · 2021RCTHerbal treatment with uva ursi extract versus fosfomycin in women with uncomplicated urinary tract infection in primary care — a double-blind randomised controlled trial (RCT)View study →Reference 2Moore et al. · 2019RCTUva-ursi extract and ibuprofen as alternative treatments for uncomplicated urinary tract infection in women (ATAFUTI) — a factorial randomised trial (RCT)View study →}.

Traditional Uses

European Folk Medicine

Bearberry leaves have been used as an antiseptic in Europe since the 1200s ^{33Reference 33Bone K · 2013Principles and Practice of Phytotherapy}.

The British Herbal Pharmacopoeia lists bearberry as a diuretic, urinary antiseptic and astringent, for cystitis, urethritis, painful urination, inflammation of the kidney pelvis and urinary gravel ^{29Reference 29British Herbal Medicine Association · 1983British Herbal Pharmacopoeia}. It has also been used for bed-wetting ^{30Reference 30Hoffmann · 2003Medical herbalism: The science and practice of herbal medicine}.

Native American Medicine

Smoking the leaves as a tobacco substitute is the most widely recorded use of kinnikinnick ^{37Reference 37Crane · 1991Arctostaphylos uva-ursi, kinnikinnick — distribution, botanical and ecological characteristics, fire response and uses — species databaseView study →}. The leaf was also added to ceremonial smoking mixtures and used for venereal disease and for inflammation and infection of the urinary tract ^{33Reference 33Bone K · 2013Principles and Practice of Phytotherapy}. The berries can be eaten as food.

Eclectic Medicine

The Eclectics used uva-ursi for chronic bladder irritation, bed-wetting, excessive mucus, blood in the urine, chronic diarrhoea, dysentery, heavy menstrual bleeding, leucorrhoea, diabetes, chronic gonorrhoea and painful, difficult urination (strangury) ^{33Reference 33Bone K · 2013Principles and Practice of Phytotherapy}.

Botany

Bearberry is a prostrate, mat-forming evergreen shrub in the heath family (Ericaceae), usually 10–50 cm tall ^{36Reference 36Parker et al. · 2009Arctostaphylos uva-ursi (Linnaeus) Sprengel — species description, habitat and distribution; genus description — floraView study →}. The genus Arctostaphylos holds 66 species, most of them North American manzanitas. Its name comes from the Greek arktos, bear, and staphyle, bunch of grapes ^{36Reference 36Parker et al. · 2009Arctostaphylos uva-ursi (Linnaeus) Sprengel — species description, habitat and distribution; genus description — floraView study →}. Uva-ursi is Latin for “bear’s grape”.

The leaves are shiny, 1–2.5 cm long and usually oblanceolate to obovate. They are dark green on top and light green underneath, with smooth edges that are often cupped ^{36Reference 36Parker et al. · 2009Arctostaphylos uva-ursi (Linnaeus) Sprengel — species description, habitat and distribution; genus description — floraView study →}.

The flowers are white to pink and urn-shaped, in short clusters (racemes). It flowers from winter to early summer, depending on the region ^{36Reference 36Parker et al. · 2009Arctostaphylos uva-ursi (Linnaeus) Sprengel — species description, habitat and distribution; genus description — floraView study →}. The fruits are round berries, 6–12 mm across, with separate stones inside ^{36Reference 36Parker et al. · 2009Arctostaphylos uva-ursi (Linnaeus) Sprengel — species description, habitat and distribution; genus description — floraView study →}.

The creeping stems root at the nodes after their second year, and bearberry spreads mainly this way rather than from seed ^{37Reference 37Crane · 1991Arctostaphylos uva-ursi, kinnikinnick — distribution, botanical and ecological characteristics, fire response and uses — species databaseView study →}. Most populations have no burl at the base and are killed by fire ^{36Reference 36Parker et al. · 2009Arctostaphylos uva-ursi (Linnaeus) Sprengel — species description, habitat and distribution; genus description — floraView study →}. Where the root crown survives it resprouts, and seed stored in the soil can survive the heat and germinate ^{37Reference 37Crane · 1991Arctostaphylos uva-ursi, kinnikinnick — distribution, botanical and ecological characteristics, fire response and uses — species databaseView study →}.

Distribution

Bearberry is a circumpolar species of the temperate and boreal northern hemisphere, found across Eurasia and in Greenland ^{36,37Reference 36Parker et al. · 2009Arctostaphylos uva-ursi (Linnaeus) Sprengel — species description, habitat and distribution; genus description — floraView study →Reference 37Crane · 1991Arctostaphylos uva-ursi, kinnikinnick — distribution, botanical and ecological characteristics, fire response and uses — species databaseView study →}.

In North America it grows from northern California north to Alaska and across Canada and the northern United States to New England and Newfoundland. It extends south in the Rocky Mountains to New Mexico, along the Atlantic coast to New Jersey and in the Appalachians to Virginia, with rare outlying populations in Georgia ^{37Reference 37Crane · 1991Arctostaphylos uva-ursi, kinnikinnick — distribution, botanical and ecological characteristics, fire response and uses — species databaseView study →}. It also occurs in Guatemala ^{36Reference 36Parker et al. · 2009Arctostaphylos uva-ursi (Linnaeus) Sprengel — species description, habitat and distribution; genus description — floraView study →}.

It grows on coastal dunes, in open, acidic temperate and boreal forests, and in high mountains on acidic, sandy or rocky soils, from sea level to 3,100 m ^{36Reference 36Parker et al. · 2009Arctostaphylos uva-ursi (Linnaeus) Sprengel — species description, habitat and distribution; genus description — floraView study →}.

Growing Conditions

Cultivation snapshot for Bearberry

LifeperennialZoneUSDA 2–7

• Hardy, drought-tolerant groundcover, full sun to part shade; prefers acidic, well-drained sandy or gritty soil. Roughly USDA zone 2–7.
• Grows poorly in hot, humid summers; established plants dislike root disturbance.

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Harvesting, Collection & Preparation

Bearberry is usually prepared as an infusion or as a liquid extract.

Cold-water extraction is preferred to preserve the arbutin and to leave behind much of the tannin. Where the astringent action is wanted, a hot infusion is used instead.

Indications

• Bladder and urinary tract infections, cystitis [leaf] ⚠Caution: In a trial against placebo, the leaf extract did not ease urinary symptoms or reduce antibiotic use. Against the antibiotic fosfomycin it cut antibiotic courses by 64% but left a higher symptom burden and more kidney infections (8 vs 2) ^1,2.
• Urethritis, painful urination and urinary gravel [leaf; British Herbal Pharmacopoeia]
• Bed-wetting [leaf; Western herbal and Eclectic use]
• Gonorrhoea and other venereal disease [leaf; Native American and Eclectic use]
• Heavy menstrual bleeding [leaf; Eclectic use]
• Chronic diarrhoea and dysentery [leaf; Eclectic use]
• Skin hyperpigmentation [leaf; topical]

Pharmacology & Research

Bearberry research covers three things: how arbutin reaches the urine, the antibacterial activity of the leaf and its compounds in the laboratory, and two trials of the leaf in women with urinary tract infections ^{1,2,3,4,5,6,7,8Reference 1Gágyor et al. · 2021RCTHerbal treatment with uva ursi extract versus fosfomycin in women with uncomplicated urinary tract infection in primary care — a double-blind randomised controlled trial (RCT)View study →Reference 2Moore et al. · 2019RCTUva-ursi extract and ibuprofen as alternative treatments for uncomplicated urinary tract infection in women (ATAFUTI) — a factorial randomised trial (RCT)View study →Reference 3Schindler et al. · 2002RCTUrinary excretion and metabolism of arbutin after oral administration of Arctostaphylos uvae ursi extract in healthy humans — a randomised crossover pharmacokinetic studyView study →Reference 4Quintus et al. · 2005Urinary excretion of arbutin metabolites after oral administration of bearberry leaf extracts — pharmacokinetic studyView study →Reference 5Cybulska et al. · 2011In vitroExtracts of Canadian First Nations medicinal plants inhibit Neisseria gonorrhoeae isolates with different antibiotic-resistance profiles — in vitro studyView study →Reference 6Deutch · 2017In vitroLimited effectiveness of over-the-counter plant preparations against the urease of Staphylococcus saprophyticus — in vitro studyView study →Reference 7Dell’Annunziata et al. · 2022In vitroIn vitro antibacterial and anti-inflammatory activity of Arctostaphylos uva-ursi leaf extract against Cutibacterium acnes — in vitro studyView study →Reference 8de Arriba et al. · 2013ReviewRisk assessment of free hydroquinone derived from Arctostaphylos uva-ursi folium herbal preparations — reviewView study →}.

Arbutin is converted to hydroquinone and excreted in the urine in humans, and the leaf is antibacterial in laboratory tests ^{3,4,5,6,7Reference 3Schindler et al. · 2002RCTUrinary excretion and metabolism of arbutin after oral administration of Arctostaphylos uvae ursi extract in healthy humans — a randomised crossover pharmacokinetic studyView study →Reference 4Quintus et al. · 2005Urinary excretion of arbutin metabolites after oral administration of bearberry leaf extracts — pharmacokinetic studyView study →Reference 5Cybulska et al. · 2011In vitroExtracts of Canadian First Nations medicinal plants inhibit Neisseria gonorrhoeae isolates with different antibiotic-resistance profiles — in vitro studyView study →Reference 6Deutch · 2017In vitroLimited effectiveness of over-the-counter plant preparations against the urease of Staphylococcus saprophyticus — in vitro studyView study →Reference 7Dell’Annunziata et al. · 2022In vitroIn vitro antibacterial and anti-inflammatory activity of Arctostaphylos uva-ursi leaf extract against Cutibacterium acnes — in vitro studyView study →}. In the two randomised trials, the leaf did not relieve symptoms better than placebo or match an antibiotic ^{1,2Reference 1Gágyor et al. · 2021RCTHerbal treatment with uva ursi extract versus fosfomycin in women with uncomplicated urinary tract infection in primary care — a double-blind randomised controlled trial (RCT)View study →Reference 2Moore et al. · 2019RCTUva-ursi extract and ibuprofen as alternative treatments for uncomplicated urinary tract infection in women (ATAFUTI) — a factorial randomised trial (RCT)View study →}.

The antioxidant, anti-inflammatory, skin-lightening, diuretic and kidney findings come mostly from cell studies or from isolated arbutin in animals ^{11,12,13,14,15,16,17,18,19,20,21,22Reference 11Lee et al. · 2012In vitroAnti-inflammatory effects of arbutin in lipopolysaccharide-stimulated BV2 microglial cells — in vitro studyView study →Reference 12Kubo et al. · 1990AnimalPharmacological studies on leaf of Arctostaphylos uva-ursi I — combined effect of methanolic extract and prednisolone on immuno-inflammation in mice (animal model)View study →Reference 13Matsuda et al. · 1990AnimalPharmacological study on Arctostaphylos uva-ursi II — combined effects of arbutin and prednisolone or dexamethasone on immuno-inflammation in mice (animal model)View study →Reference 14Boo · 2021ReviewArbutin as a skin-depigmenting agent with antimelanogenic and antioxidant properties — reviewView study →Reference 15Sugimoto et al. · 2004In vitroInhibitory effects of α-arbutin on melanin synthesis in cultured human melanoma cells and a three-dimensional human skin model — in vitro studyView study →Reference 16Matsuo et al. · 1997In vitroAnti-tyrosinase activity constituents of Arctostaphylos uva-ursi — in vitro studyView study →Reference 17Wang et al. · 2004Case reportBull’s-eye maculopathy secondary to herbal toxicity from uva ursi — case reportView study →Reference 18Beaux et al. · 1999AnimalEffect of extracts of Orthosiphon stamineus, Hieracium pilosella, Sambucus nigra and Arctostaphylos uva-ursi in rats — animal diuresis studyView study →Reference 19Nazeer et al. · 2025AnimalToxicological profiling and diuretic potential of arbutin via aldosterone synthase gene inhibition — rat studyView study →Reference 20Zhang et al. · 2021AnimalArbutin attenuates LPS-induced acute kidney injury by inhibiting inflammation and apoptosis via the PI3K/Akt/Nrf2 pathway — rat studyView study →Reference 21Sirinyildiz et al. · 2025AnimalArbutin as a potential nephroprotective agent — dose-related effects in renal ischaemia-reperfusion (rat model)View study →Reference 22Li et al. · 2011In vitroArbutin inhibits TCCSUP human bladder-cancer cell proliferation via up-regulation of p21 — in vitro studyView study →}.

1. Antibacterial & Urinary Antiseptic

The leaf’s arbutin is broken down to hydroquinone, which the liver binds to glucuronide and sulfate before it is excreted in the urine. In 16 healthy volunteers, 65–67% of an oral arbutin dose from a leaf extract was recovered in the urine as hydroquinone and its conjugates ^{3Reference 3Schindler et al. · 2002RCTUrinary excretion and metabolism of arbutin after oral administration of Arctostaphylos uvae ursi extract in healthy humans — a randomised crossover pharmacokinetic studyView study →}. In a pilot study of three volunteers, more than 75% was excreted within 24 hours, mostly as the conjugates; free hydroquinone was negligible in two of them and 5.6% of the dose in the third ^{4Reference 4Quintus et al. · 2005Urinary excretion of arbutin metabolites after oral administration of bearberry leaf extracts — pharmacokinetic studyView study →}.

A regulatory risk assessment estimated that the recommended daily dose (420 mg of hydroquinone derivatives, as arbutin) releases free hydroquinone into the urine at a maximum of 11 µg/kg of body weight a day ^{8Reference 8de Arriba et al. · 2013ReviewRisk assessment of free hydroquinone derived from Arctostaphylos uva-ursi folium herbal preparations — reviewView study →}.

In the laboratory, an ethanolic leaf extract inhibited all 28 tested Neisseria gonorrhoeae isolates at 32 µg/mL, whatever their antibiotic resistance ^{5Reference 5Cybulska et al. · 2011In vitroExtracts of Canadian First Nations medicinal plants inhibit Neisseria gonorrhoeae isolates with different antibiotic-resistance profiles — in vitro studyView study →}. The leaf is bacteriostatic against Cutibacterium acnes ^{7Reference 7Dell’Annunziata et al. · 2022In vitroIn vitro antibacterial and anti-inflammatory activity of Arctostaphylos uva-ursi leaf extract against Cutibacterium acnes — in vitro studyView study →}.

Of 14 over-the-counter urinary plant preparations, a uva-ursi product and green tea cut the urease activity of Staphylococcus saprophyticus, a urinary pathogen, by more than 75%. Most of the others had little or no effect ^{6Reference 6Deutch · 2017In vitroLimited effectiveness of over-the-counter plant preparations against the urease of Staphylococcus saprophyticus — in vitro studyView study →}.

The tannin corilagin, isolated from bearberry, sharply lowers the dose of β-lactam antibiotics needed against methicillin-resistant Staphylococcus aureus by inactivating the resistance protein PBP2a. The same study tested tellimagrandin I, isolated from dog rose, with the same result ^{28Reference 28Shiota et al. · 2004In vitroMechanisms of action of corilagin and tellimagrandin I that potentiate β-lactams against methicillin-resistant Staphylococcus aureus — in vitro studyView study →}.

Antibacterial activity is reported to be greater in alkaline urine, which is why texts advise alkalising the urine during use ^{29Reference 29British Herbal Medicine Association · 1983British Herbal Pharmacopoeia}.

Two randomised trials have tested the leaf in women with uncomplicated urinary tract infections.

In the ATAFUTI factorial trial, 382 women aged 18–70 were all given a back-up antibiotic prescription. Uva-ursi extract did not reduce urinary-frequency symptoms on days 2–4 compared with placebo, and did not significantly reduce antibiotic use (39.9% vs 47.4%). No upper urinary tract infections were recorded ^{2Reference 2Moore et al. · 2019RCTUva-ursi extract and ibuprofen as alternative treatments for uncomplicated urinary tract infection in women (ATAFUTI) — a factorial randomised trial (RCT)View study →}.

In a German trial in 42 family practices, 398 women received uva-ursi extract or the antibiotic fosfomycin. Uva-ursi cut antibiotic courses by 63.6%, but the symptom burden was 136.5% of that with fosfomycin, failing the test of non-inferiority. Eight women developed a kidney infection on uva-ursi and two on fosfomycin ^{1Reference 1Gágyor et al. · 2021RCTHerbal treatment with uva ursi extract versus fosfomycin in women with uncomplicated urinary tract infection in primary care — a double-blind randomised controlled trial (RCT)View study →}.

Gap: neither trial showed that the leaf relieves urinary symptoms, and kidney infections were more frequent than with fosfomycin in the one trial that compared them.

2. Antioxidant

Bearberry leaf is rich in phenolics: arbutin, hydrolysable tannins, and flavonols such as quercetin and myricetin glycosides. Leaf extracts consistently scavenge free radicals and reduce iron in laboratory assays, with the effect tracking phenolic content ^{9,10Reference 9Sugier et al. · 2021In vitroChemical characteristics and antioxidant activity of Arctostaphylos uva-ursi leaf at the southern border of its European range — in vitro studyView study →Reference 10Sugier et al. · 2022In vitroVariation in population and solvents determining chemical composition and antioxidant potential of Arctostaphylos uva-ursi leaf extracts — in vitro studyView study →}.

Content and activity vary between populations, habitats and extraction solvents ^{9,10Reference 9Sugier et al. · 2021In vitroChemical characteristics and antioxidant activity of Arctostaphylos uva-ursi leaf at the southern border of its European range — in vitro studyView study →Reference 10Sugier et al. · 2022In vitroVariation in population and solvents determining chemical composition and antioxidant potential of Arctostaphylos uva-ursi leaf extracts — in vitro studyView study →}. In water extracts, free hydroquinone contributed to the antioxidant activity as well as the phenolics ^{10Reference 10Sugier et al. · 2022In vitroVariation in population and solvents determining chemical composition and antioxidant potential of Arctostaphylos uva-ursi leaf extracts — in vitro studyView study →}.

In one study, low concentrations of a water extract of the leaf stimulated biofilm formation by Escherichia coli up to threefold, an effect the authors linked to the prooxidant properties of its polyphenols ^{27Reference 27Samoilova et al. · 2014In vitroMedicinal plant extracts can variously modify biofilm formation in Escherichia coli — in vitro studyView study →}.

3. Anti-Inflammatory

Isolated arbutin suppressed lipopolysaccharide-induced nitric oxide, iNOS, COX-2, TNF-α, IL-1β and IL-6 in mouse microglial cells by inhibiting NF-κB ^{11Reference 11Lee et al. · 2012In vitroAnti-inflammatory effects of arbutin in lipopolysaccharide-stimulated BV2 microglial cells — in vitro studyView study →}. A leaf extract blocked the release of IL-1β, IL-6, IL-8 and TNF-α from skin cells exposed to C. acnes ^{7Reference 7Dell’Annunziata et al. · 2022In vitroIn vitro antibacterial and anti-inflammatory activity of Arctostaphylos uva-ursi leaf extract against Cutibacterium acnes — in vitro studyView study →}.

In mice with contact dermatitis, a 50% methanolic leaf extract reduced swelling when given 24 hours after the challenge, and it and arbutin both added to the effect of prednisolone ^{12Reference 12Kubo et al. · 1990AnimalPharmacological studies on leaf of Arctostaphylos uva-ursi I — combined effect of methanolic extract and prednisolone on immuno-inflammation in mice (animal model)View study →}. Arbutin also added to the effect of dexamethasone. Unlike the two steroids, arbutin on its own did not shrink the thymus or spleen ^{13Reference 13Matsuda et al. · 1990AnimalPharmacological study on Arctostaphylos uva-ursi II — combined effects of arbutin and prednisolone or dexamethasone on immuno-inflammation in mice (animal model)View study →}.

Gap: entirely preclinical and mostly on isolated arbutin; there are no human anti-inflammatory data for the leaf.

4. Skin Depigmenting (Anti-Tyrosinase)

Arbutin is a well-studied tyrosinase inhibitor and a common cosmetic skin-lightening ingredient ^{14Reference 14Boo · 2021ReviewArbutin as a skin-depigmenting agent with antimelanogenic and antioxidant properties — reviewView study →}. Its synthetic isomer, α-arbutin, reduced melanin synthesis to 76% of control in human melanoma cells and to 40% in a three-dimensional skin model ^{15Reference 15Sugimoto et al. · 2004In vitroInhibitory effects of α-arbutin on melanin synthesis in cultured human melanoma cells and a three-dimensional human skin model — in vitro studyView study →}. The anti-tyrosinase constituents of uva-ursi leaf have been isolated ^{16Reference 16Matsuo et al. · 1997In vitroAnti-tyrosinase activity constituents of Arctostaphylos uva-ursi — in vitro studyView study →}.

A 56-year-old woman who took uva-ursi for three years developed a bull’s-eye maculopathy in both eyes, a pattern of retinal damage. The authors linked it to uva-ursi’s inhibition of melanin synthesis ^{17Reference 17Wang et al. · 2004Case reportBull’s-eye maculopathy secondary to herbal toxicity from uva ursi — case reportView study →}.

Gap: the skin-lightening evidence is for arbutin applied to the skin as a cosmetic, not for the leaf; taken internally over years, the same activity has been linked to retinal harm.

5. Diuretic

In rats, an aqueous uva-ursi extract increased urine flow. Unlike Orthosiphon and Sambucus extracts in the same study, it did not increase sodium excretion ^{18Reference 18Beaux et al. · 1999AnimalEffect of extracts of Orthosiphon stamineus, Hieracium pilosella, Sambucus nigra and Arctostaphylos uva-ursi in rats — animal diuresis studyView study →}.

In a 2025 study, isolated arbutin injected at 25–75 mg/kg acted as a diuretic and increased sodium excretion. It lowered expression of the aldosterone synthase gene ^{19Reference 19Nazeer et al. · 2025AnimalToxicological profiling and diuretic potential of arbutin via aldosterone synthase gene inhibition — rat studyView study →}.

6. Nephroprotective (Arbutin)

Isolated arbutin protected rat kidneys against lipopolysaccharide-induced acute injury, reducing inflammation and cell death through the PI3K/Akt/Nrf2 pathway ^{20Reference 20Zhang et al. · 2021AnimalArbutin attenuates LPS-induced acute kidney injury by inhibiting inflammation and apoptosis via the PI3K/Akt/Nrf2 pathway — rat studyView study →}.

Given by mouth for 14 days before renal ischaemia-reperfusion injury in rats, arbutin reduced kidney damage. The higher dose (1,000 mg/kg) left the kidney looking close to normal, while the lower dose (250 mg/kg) left mild changes ^{21Reference 21Sirinyildiz et al. · 2025AnimalArbutin as a potential nephroprotective agent — dose-related effects in renal ischaemia-reperfusion (rat model)View study →}.

Gap: these are rodent studies of isolated arbutin in injury models unrelated to bearberry’s traditional use; none tests the leaf or human kidneys.

7. Bladder Anti-Proliferative

Arbutin slowed the growth of TCCSUP human bladder-cancer cells in a concentration- and time-dependent way. It disrupted the cell cycle through ERK inactivation and higher p21 ^{22Reference 22Li et al. · 2011In vitroArbutin inhibits TCCSUP human bladder-cancer cell proliferation via up-regulation of p21 — in vitro studyView study →}.

A separate study exposed T24 bladder cells to hydroquinone from a uva-ursi preparation. Recommended doses were toxic to the cells only when all the hydroquinone conjugates were converted to free hydroquinone (320 and 900 µg/mL). One cup of the therapeutic dose raised oxidative stress after four hours of exposure, and 17 stress-response proteins were up-regulated ^{23Reference 23Huđek Turković et al. · 2022In vitroProteome changes in human bladder T24 cells induced by hydroquinone derived from Arctostaphylos uva-ursi — in vitro studyView study →}.

Mechanisms

Arbutin is hydrolysed in the intestine to hydroquinone, absorbed, bound to glucuronide and sulfate in the liver, and excreted in the urine ^{8,34Reference 8de Arriba et al. · 2013ReviewRisk assessment of free hydroquinone derived from Arctostaphylos uva-ursi folium herbal preparations — reviewView study →Reference 34Hansel R et al. · 1999Berlin: Springer-Verlag}. The bacterium Escherichia coli can itself split arbutin to release hydroquinone ^{35Reference 35Siegers C et al. · 2003Bacterial deconjugation of arbutin by Escherichia coli}. Free hydroquinone is the antibacterial compound, and its activity is reported to be greater in alkaline urine ^{29Reference 29British Herbal Medicine Association · 1983British Herbal Pharmacopoeia}.

The hydrolysable tannins give the leaf its astringency. Isolated arbutin has also been studied for anti-inflammatory, antioxidant and tyrosinase-inhibiting activity, mostly in cells and animals.

Clinical Trials

Bearberry is one of the few single herbs tested in placebo-controlled trials for urinary tract infection. Two are complete (ATAFUTI and the German fosfomycin trial), a human pharmacokinetic study confirms that hydroquinone reaches the urine, and a trial against fosfomycin (BRUMI) has been registered. No trials have been terminated ^{1,2,3,4,25Reference 1Gágyor et al. · 2021RCTHerbal treatment with uva ursi extract versus fosfomycin in women with uncomplicated urinary tract infection in primary care — a double-blind randomised controlled trial (RCT)View study →Reference 2Moore et al. · 2019RCTUva-ursi extract and ibuprofen as alternative treatments for uncomplicated urinary tract infection in women (ATAFUTI) — a factorial randomised trial (RCT)View study →Reference 3Schindler et al. · 2002RCTUrinary excretion and metabolism of arbutin after oral administration of Arctostaphylos uvae ursi extract in healthy humans — a randomised crossover pharmacokinetic studyView study →Reference 4Quintus et al. · 2005Urinary excretion of arbutin metabolites after oral administration of bearberry leaf extracts — pharmacokinetic studyView study →Reference 25Tóth et al. · 2022RCTBearberry in the treatment of acute uncomplicated cystitis (BRUMI) — protocol of a multicentre randomised double-blind clinical trialView study →}.

Last checked: July 2026.

Phytochemistry

The main constituent of bearberry leaf is arbutin, a hydroquinone glycoside. An analysis of leaf samples measured arbutin at 47–107 mg/g (4.7–10.7%), pentagalloylglucose at 6.6–12.9 mg/g and quercetin 3-galactoside and 3-glucoside at 2.7–5.7 mg/g, with quinic and ellagic acid also high ^{24Reference 24Song et al. · 2021Discovery and characterisation of phenolic compounds in bearberry leaves using LC-ion-mobility-HRMS — analytical studyView study →}. The European Pharmacopoeia requires at least 7% arbutin in the dried leaf ^{26Reference 26Panusa et al. · 2015UHPLC-PDA-ESI-TOF/MS metabolic profiling of Arctostaphylos pungens and A. uva-ursi — a comparative study of leaf phenolics (species-adulteration relevance)View study →}.

Arbutin is broken down in the body to free hydroquinone. Water extracts of the leaf also contain free hydroquinone, at 7–13 mg/g across twelve wild populations ^{10Reference 10Sugier et al. · 2022In vitroVariation in population and solvents determining chemical composition and antioxidant potential of Arctostaphylos uva-ursi leaf extracts — in vitro studyView study →}. Conversion to hydroquinone in the bladder is reported to be less efficient in acidic urine ^{29Reference 29British Herbal Medicine Association · 1983British Herbal Pharmacopoeia}.

The same analysis identified 88 compounds in the leaf: 14 arbutin derivatives, 33 hydrolysable tannins, 6 flavanols, 26 flavonols and 9 sugar derivatives ^{24Reference 24Song et al. · 2021Discovery and characterisation of phenolic compounds in bearberry leaves using LC-ion-mobility-HRMS — analytical studyView study →}. The tannins include gallotannins and the ellagitannin corilagin ^{24,28Reference 24Song et al. · 2021Discovery and characterisation of phenolic compounds in bearberry leaves using LC-ion-mobility-HRMS — analytical studyView study →Reference 28Shiota et al. · 2004In vitroMechanisms of action of corilagin and tellimagrandin I that potentiate β-lactams against methicillin-resistant Staphylococcus aureus — in vitro studyView study →}. Levels of hyperoside, corilagin and methylarbutin vary widely between plants from heathland and pine forest ^{9Reference 9Sugier et al. · 2021In vitroChemical characteristics and antioxidant activity of Arctostaphylos uva-ursi leaf at the southern border of its European range — in vitro studyView study →}.

Other reported constituents include myricetin glycosides, the iridoid monotropein, piceoside, the tellimagrandins, and the triterpenes ursolic acid and β-amyrin ^{30,31,33Reference 30Hoffmann · 2003Medical herbalism: The science and practice of herbal medicineReference 31Wren · 1968Potter’s new cyclopaedia of botanical drugs and preparationsReference 33Bone K · 2013Principles and Practice of Phytotherapy}.

Arctostaphylos pungens leaf, sometimes sold as bearberry, contains less arbutin and less tetra- and pentagalloylglucose, and has a different flavonol profile ^{26Reference 26Panusa et al. · 2015UHPLC-PDA-ESI-TOF/MS metabolic profiling of Arctostaphylos pungens and A. uva-ursi — a comparative study of leaf phenolics (species-adulteration relevance)View study →}.

Arbutin occurs in the leaves, bark and roots. The hydroquinone it forms inhibits the growth of surrounding plants, and arbutin is found in many plants that survive extreme and prolonged dehydration ^{33Reference 33Bone K · 2013Principles and Practice of Phytotherapy}.

Constituent Summary

Figures are for dried leaf; arbutin content varies with population, habitat and season ^{10,24Reference 10Sugier et al. · 2022In vitroVariation in population and solvents determining chemical composition and antioxidant potential of Arctostaphylos uva-ursi leaf extracts — in vitro studyView study →Reference 24Song et al. · 2021Discovery and characterisation of phenolic compounds in bearberry leaves using LC-ion-mobility-HRMS — analytical studyView study →}.

Dosage

The clinical and pharmacokinetic studies used standardised dry extracts dosed by their arbutin content, not a measured amount of whole leaf.

The dried-leaf figure assumes 7–10.7% arbutin in the leaf ^{24,26Reference 24Song et al. · 2021Discovery and characterisation of phenolic compounds in bearberry leaves using LC-ion-mobility-HRMS — analytical studyView study →Reference 26Panusa et al. · 2015UHPLC-PDA-ESI-TOF/MS metabolic profiling of Arctostaphylos pungens and A. uva-ursi — a comparative study of leaf phenolics (species-adulteration relevance)View study →}. It is a rough guide, not a conversion factor.

Traditional Dosage

Western herbal practice uses the whole leaf as a cold infusion, a tincture or a liquid extract.

Safety & Pregnancy

Bearberry is used in short courses: up to 5 days at a time and no more than 3 courses a year. It is not used in pregnancy, while breastfeeding, in children under 12 or with kidney disease.

Full Safety Detail

Short courses. The standard limit is up to 5 consecutive days and no more than 3 courses a year.

Hydroquinone. At the recommended daily dose, free hydroquinone in the urine peaks at about 11 µg/kg of body weight a day. That is below the 100 µg/kg a day that the same risk assessment set as a negligible-risk level. The assessment found no human evidence that free hydroquinone causes convulsions, liver or kidney damage, or tumours ^{8Reference 8de Arriba et al. · 2013ReviewRisk assessment of free hydroquinone derived from Arctostaphylos uva-ursi folium herbal preparations — reviewView study →}. In bladder cells, hydroquinone was toxic only when all of it was converted to the free form ^{23Reference 23Huđek Turković et al. · 2022In vitroProteome changes in human bladder T24 cells induced by hydroquinone derived from Arctostaphylos uva-ursi — in vitro studyView study →}.

Long-term use. A 56-year-old woman who took uva-ursi daily for three years developed a bull’s-eye maculopathy in both eyes ^{17Reference 17Wang et al. · 2004Case reportBull’s-eye maculopathy secondary to herbal toxicity from uva ursi — case reportView study →}.

Established infection. In the German trial against fosfomycin, women taking uva-ursi had a higher symptom burden and more kidney infections (8 vs 2) ^{1Reference 1Gágyor et al. · 2021RCTHerbal treatment with uva ursi extract versus fosfomycin in women with uncomplicated urinary tract infection in primary care — a double-blind randomised controlled trial (RCT)View study →}. It is not a replacement for antibiotics when an infection is established.

Stomach. The leaf’s high tannin content can cause nausea and stomach irritation. A cold-water infusion extracts less tannin.

Urine acidity. Substances that acidify the urine reduce the release of hydroquinone and the antibacterial effect ^{29Reference 29British Herbal Medicine Association · 1983British Herbal Pharmacopoeia}.

Drug metabolism. In laboratory tests, extracts of commercial uva-ursi products inhibited CYP3A4 and CYP2C19 and altered P-glycoprotein activity; whether this matters in people has not been studied ^{38Reference 38Chauhan et al. · 2007In vitroIn vitro activity of uva-ursi against cytochrome P450 isoenzymes and P-glycoprotein — in vitro studyView study →}. No formal drug-interaction studies in animals or people have been published.

Children and kidney disease. Bearberry is not used in children under 12 or in people with kidney disorders.

References

1. Gágyor, I., et al. (2021). Herbal treatment with uva ursi extract versus fosfomycin in women with uncomplicated urinary tract infection in primary care — a double-blind randomised controlled trial (RCT). Clinical Microbiology and Infection. https://pubmed.ncbi.nlm.nih.gov/34111592/
2. Moore, M., et al. (2019). Uva-ursi extract and ibuprofen as alternative treatments for uncomplicated urinary tract infection in women (ATAFUTI) — a factorial randomised trial (RCT). Clinical Microbiology and Infection. https://pubmed.ncbi.nlm.nih.gov/30685500/
3. Schindler, G., et al. (2002). Urinary excretion and metabolism of arbutin after oral administration of Arctostaphylos uvae ursi extract in healthy humans — a randomised crossover pharmacokinetic study. Journal of Clinical Pharmacology. https://pubmed.ncbi.nlm.nih.gov/12162475/
4. Quintus, J., et al. (2005). Urinary excretion of arbutin metabolites after oral administration of bearberry leaf extracts — pharmacokinetic study. Planta Medica. https://pubmed.ncbi.nlm.nih.gov/15729623/
5. Cybulska, P., et al. (2011). Extracts of Canadian First Nations medicinal plants inhibit Neisseria gonorrhoeae isolates with different antibiotic-resistance profiles — in vitro study. Sexually Transmitted Diseases. https://pubmed.ncbi.nlm.nih.gov/21301385/
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7. Dell’Annunziata, F., et al. (2022). In vitro antibacterial and anti-inflammatory activity of Arctostaphylos uva-ursi leaf extract against Cutibacterium acnes — in vitro study. Pharmaceutics. https://pubmed.ncbi.nlm.nih.gov/36145700/
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9. Sugier, P., et al. (2021). Chemical characteristics and antioxidant activity of Arctostaphylos uva-ursi leaf at the southern border of its European range — in vitro study. Molecules. https://pubmed.ncbi.nlm.nih.gov/34946773/
10. Sugier, P., et al. (2022). Variation in population and solvents determining chemical composition and antioxidant potential of Arctostaphylos uva-ursi leaf extracts — in vitro study. Molecules. https://pubmed.ncbi.nlm.nih.gov/35408643/
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23. Huđek Turković, A., et al. (2022). Proteome changes in human bladder T24 cells induced by hydroquinone derived from Arctostaphylos uva-ursi — in vitro study. Journal of Ethnopharmacology. https://pubmed.ncbi.nlm.nih.gov/35143933/
24. Song, X. C., et al. (2021). Discovery and characterisation of phenolic compounds in bearberry leaves using LC-ion-mobility-HRMS — analytical study. Journal of Agricultural and Food Chemistry. https://pubmed.ncbi.nlm.nih.gov/34493038/
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