Bearberry

What Is Bearberry?

Bearberry is a small shrub native to the temperate climates of North America and Europe. The leaves are almost exclusive for treating bladder and urinary tract infections but are also used to reduce inflammation topically and internally.

Bearberry is mainly used as a treatment for urinary tract infections, venereal disease, and prostatitis. Some of the glycosides contained in the leaves become active on passing into the urine, where the antimicrobial components can then take effect without being subjected to metabolism by the liver.

Bearberry must be used cautiously, and never more than five days in a row or more than three times a year.

What Is Bearberry Used For?

The main traditional uses of bearberry are for urinary tract infections and inflammation of the urinary tract. This can involve cystitis, vaginal infection, kidney calculi, and prostatitis. The leaf’s hydroquinone esters are the basis of this urinary-antiseptic use — the best-known and most popular application of bearberry medicinally.

It is important to be honest about how well this traditional reputation holds up against modern testing. Bearberry is one of the few single herbs put through placebo-controlled trials for uncomplicated UTI, and the results are humbling: the leaf produced no clear symptom benefit over placebo, and against an antibiotic it left more women with persistent symptoms and more cases of pyelonephritis (see Pharmacology & Research below) ^{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 →}. Bearberry should therefore be regarded as a traditional urinary antiseptic rather than a proven cure, and it should not replace antibiotics where an infection is established.

Traditional Uses

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

In North America, uva-ursi has been used as an addition to ceremonial smoking rituals, as well as for venereal disease and inflammation and infection of the urinary tract. ^{33Reference 33Bone K · 2013Principles and Practice of Phytotherapy}.

The Eclectics used uva-ursi to treat chronic bladder irritations, enuresis, excessive mucous, blood in the urine, chronic diarrhea, dysentery, menorrhagia, leucorrhea, diabetes, chronic gonorrhea, and strangury ^{33Reference 33Bone K · 2013Principles and Practice of Phytotherapy}.

The berries of uva-ursi can be eaten as food, as well.

Uva-ursi has also been used to whiten skin and may be used to treat hyperpigmentation disorders ^{33Reference 33Bone K · 2013Principles and Practice of Phytotherapy}. This tracks with the modern finding that its arbutin is a validated tyrosinase inhibitor — though that activity belongs to purified arbutin applied topically as a cosmetic, not to the leaf taken internally.

Bearberry has been used in the past to treat bed wetting ^{30Reference 30Hoffmann · 2003Medical herbalism: The science and practice of herbal medicine}, which is likely due to its well known astringing and tonifying actions to the urinary system.

The British herbal pharmacopoeia lists bearberry as a diuretic, urinary antiseptic, and astringent useful for cystitis, urethritis, dysuria, pyelitis, and lithuria ^{29Reference 29British Herbal Medicine Association · 1983British Herbal Pharmacopoeia}.

Botanical Information

The Arctostaphylos genus contains about 60 species. The name uva-ursi is Latin for “bear’s grape” (uva = grape, ursi = of the bear).

It prefers well-draining mountainous slopes, but can also be found growing throughout rolling fields and pastures in temperate regions.

The flowers are small, pink, and bell-shaped arranged in drooping clusters. ^{33Reference 33Bone K · 2013Principles and Practice of Phytotherapy}. The leaves of bearberry are characteristically obovate, with a dark green top and silvery-grey bottom.

Habitat, Ecology & Distribution

Arctostaphylos is native to Europe, Asia, and the northern United States and Canada. The Arctostaphylos genus is distributed across the northern hemisphere. ^{29,33Reference 29British Herbal Medicine Association · 1983British Herbal PharmacopoeiaReference 33Bone K · 2013Principles and Practice of Phytotherapy}.

It prefers to grow on rocky hills in the mountains but can be found in fields and near rivers or sandy beaches/dunes as well. Bearberry proliferated well after a fire, as the seeds are fire resistant and require cold treatment to germinate. In the absence of fires, it spreads mainly through vegetative growth. ^{32Reference 32Small et al. · 1999Canadian medicinal cropsView study →}.

Harvesting, Collection & Preparation

Bearberry is usually prepared as an infusion or as a liquid extract. Cold water extraction is the preferred extraction technique in order to better preserve the arbutin, and helps to eliminate a lot of the tannins. This would not be preferred in cases where it’s primarily the astringent benefits that are desired of the plant.

Phytochemistry

The defining constituent of bearberry leaf is arbutin, a hydroquinone glycoside that is hydrolysed to free hydroquinone — the urinary antiseptic principle — after ingestion. It is accompanied by smaller amounts of methylarbutin and by a high load of hydrolysable tannins (mainly gallotannins such as pentagalloylglucose, plus the ellagitannins corilagin and tellimagrandin I), which give the leaf its strong astringency. A spread of flavonoids (quercetin and myricetin glycosides, including hyperoside), the iridoid monotropein, the acetophenone glycoside piceoside, phenolic acids and triterpenes such as ursolic acid and β-amyrin round out the profile. Modern LC–ion-mobility profiling identifies some 88 phenolics in the leaf, with arbutin at 47–107 mg/g and its content varying severalfold with population, season and provenance. ^{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}.

The arbutin contained in the leaves, bark, and roots of uva-ursi forms a chemical called hydroquinone, which inhibits the growth of surrounding plants. Arbutin has also been noted to exist in many plants that have developed the ability to survive extreme and prolonged dehydration. ^{33Reference 33Bone K · 2013Principles and Practice of Phytotherapy}. Arbutin has also been reported to convert to hydroquinone in the bladder less efficiently with acidic urine. This is why many texts suggest alkalizing the urine along with the use of bearberry for best results as an antimicrobial ^{29Reference 29British Herbal Medicine Association · 1983British Herbal Pharmacopoeia}.

Constituent Summary

Figures are percent of dried leaf; arbutin and tannin levels vary substantially with season and provenance (arbutin reported 5–17%). Entries marked No Data are documented qualitatively only.

Hydroquinone glycosides

Grouped by class · 4 compoundsExpand all|Collapse all

GroupCompoundAmount

Quinone4 compounds3 with data

QuinoneArbutin~5–17% (pharmacopoeial min. 7%)

QuinoneMethylarbutinup to ~4%

QuinoneHydroquinonemostly bound as arbutin

QuinonePiceosideNo data

Tannins & phenolic acids

Grouped by class · 6 compoundsExpand all|Collapse all

GroupCompoundAmount

Tannin4 compounds2 with data

TanninGallotanninstotal tannins up to ~15%

TanninPentagalloylglucose~6.6–12.9 mg/g

TanninCorilaginNo data

TanninTellimagrandin INo data

Phenolic Acid2 compoundsno data

Phenolic AcidGallic acidNo data

Phenolic AcidEllagic acidNo data

Flavonoids

Grouped by class · 4 compoundsExpand all|Collapse all

GroupCompoundAmount

Flavonoid4 compounds1 with data

FlavonoidQuercetinglycosides ~2.7–5.7 mg/g

FlavonoidMyricetinNo data

FlavonoidIsoquercitrinNo data

FlavonoidHyperosideNo data

Terpenoids & iridoids

Grouped by class · 3 compoundsExpand all|Collapse all

GroupCompoundAmount

Triterpene2 compoundsno data

TriterpeneUrsolic acidNo data

Triterpeneβ-AmyrinNo data

Iridoid1 compoundno data

IridoidMonotropeinNo data

Pharmacology & Research

The research literature on bearberry (Arctostaphylos uva-ursi) is moderate in size and unusually top-heavy for a traditional herb: its defining constituent, arbutin, has been studied in humans for pharmacokinetics, and the leaf has now been through two placebo-controlled clinical trials for urinary tract infection (UTI) — a rarity in phytotherapy. The honest headline is that the mechanism is well mapped while the clinical payoff is not: arbutin is reliably converted to hydroquinone and delivered to 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 →}, hydroquinone and the leaf’s phenolics are antibacterial in vitro ^{5,6,7Reference 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 →}, yet the two randomised trials that tested actual symptom relief were null-to-mixed and raised safety questions ^{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 →}. Most other claimed activities — antioxidant, anti-inflammatory, skin-lightening, diuretic — rest on in vitro work or on isolated arbutin in animal models rather than on the whole leaf as it is taken. A recurring caveat runs through all of it: arbutin content varies severalfold with provenance, season and species (adulteration with lower-arbutin A. pungens is documented), so results tied to one extract do not transfer cleanly to another ^{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 →}.

0. Evidence by indication

Support is an experimental score I’m building — a composite weighted by study type (human > animal > in vitro > review) and study volume. It’s a beta: a fast way to rank strength of evidence at a glance, not a validated metric, and I’ll keep honing the formula over time. Each indication name links down to its write-up.

Indication	Support	Rests on
Antibacterial & urinary antiseptic	███████░░░ 66%	Strong in vitro + human PK proving urinary hydroquinone delivery + pharmacopoeial use; but two RCTs of the leaf for UTI were null/mixed.
Antioxidant	██████░░░░ 62%	Consistent in vitro radical-scavenging across many leaf extracts; high phenolic load; no human data, and a prooxidant paradox in bacteria.
Anti-inflammatory	██████░░░░ 58%	Arbutin suppresses NF-κB/COX-2/iNOS in vitro and potentiates corticosteroids in mice; whole-leaf and human data absent.
Skin depigmenting (anti-tyrosinase)	█████░░░░░ 48%	Arbutin is a validated tyrosinase inhibitor, but as a topical cosmetic — a preparation mismatch for a leaf taken internally for UTI.
Diuretic	████░░░░░░ 40%	One rat study shows increased urine flow (no natriuresis); a 2025 arbutin mechanism paper; largely pharmacopoeial/traditional.
Nephroprotective (arbutin)	███░░░░░░░ 34%	Isolated arbutin protects rodent kidney against LPS and ischaemia; constituent-level, animal-only, not the whole leaf.
Bladder anti-proliferative	███░░░░░░░ 30%	Single bladder-carcinoma cell line; arbutin only; in vitro.

1. Antibacterial & urinary antiseptic

This is bearberry’s defining use, and the mechanism is well established. The leaf’s arbutin is hydrolysed — by gut microbiota and tissue β-glucosidases — to free hydroquinone, which is conjugated in the liver and excreted renally; human pharmacokinetic studies confirm that more than 60% of an oral arbutin dose is recovered in urine as hydroquinone glucuronide and sulphate within 24 hours, with free hydroquinone the presumed antiseptic principle in the bladder ^{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 →}. In vitro, ethanolic leaf extract inhibited all tested Neisseria gonorrhoeae isolates (MIC ≈ 32 µg/mL) regardless of antibiotic-resistance profile ^{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 →}, and — while most over-the-counter UTI plant preparations were ineffective — the uva-ursi preparation reduced the urease activity of Staphylococcus saprophyticus, a lower-UTI pathogen, by more than 75% ^{6Reference 6Deutch · 2017In vitroLimited effectiveness of over-the-counter plant preparations against the urease of Staphylococcus saprophyticus — in vitro studyView study →}. Two of the leaf’s hydrolysable tannins, corilagin and tellimagrandin I, also markedly potentiate β-lactams against methicillin-resistant Staphylococcus aureus by inactivating PBP2a in vitro ^{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 potency is reported to rise in alkaline urine, the rationale behind the traditional advice to alkalinise. Whether enough free hydroquinone reaches the urine to be bactericidal at achievable doses is itself contested: a regulatory risk assessment estimated maximum urinary free-hydroquinone exposure at only ~11 µg/kg/day at recommended doses — safe, but modest ^{8Reference 8de Arriba et al. · 2013ReviewRisk assessment of free hydroquinone derived from Arctostaphylos uva-ursi folium herbal preparations — reviewView study →}. The clinical translation, however, is where the evidence turns: in the ATAFUTI factorial RCT (n=382) uva-ursi produced no reduction in urinary-frequency symptoms versus placebo and no significant fall in antibiotic use ^{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 →}, and in the German REGATTA/Gágyor trial (n=398) initial uva-ursi cut antibiotic courses by ~64% versus fosfomycin but failed non-inferiority for symptom burden and produced more cases of pyelonephritis (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 →}.

Gap: the two RCTs of the actual leaf preparation show the antiseptic effect measurable in a test tube does not reliably relieve symptoms in patients, and may let some infections ascend — clinical efficacy is unproven and possibly outweighed by risk.

2. Antioxidant

Bearberry leaf is phenolic-rich — arbutin, hydrolysable tannins, and flavonols such as quercetin and myricetin glycosides — and shows consistent free-radical scavenging and ferric-reducing activity across many in vitro extract studies, with potency tracking total 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 →}. Modern LC-ion-mobility-HRMS profiling identifies 88 phenolics in the leaf — arbutin (47–107 mg/g), pentagalloylglucose and quercetin glycosides dominating — underlining how concentrated and variable the phenolic load is ^{24Reference 24Song et al. · 2021Discovery and characterisation of phenolic compounds in bearberry leaves using LC-ion-mobility-HRMS — analytical studyView study →}. Content and activity vary widely by population, habitat and solvent, so a single “antioxidant capacity” figure is misleading ^{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 →}. A notable wrinkle: in bacterial systems the same polyphenols behave as prooxidants, generating hydrogen peroxide and inducing catalase — a reminder that “antioxidant” is assay-dependent, not an intrinsic whole-organism property ^{27Reference 27Samoilova et al. · 2014In vitroMedicinal plant extracts can variously modify biofilm formation in Escherichia coli — in vitro studyView study →}.

Gap: every antioxidant result is in vitro or in food-model systems; there is no human biomarker or clinical-outcome evidence, and the prooxidant behaviour in some conditions complicates the simple narrative.

3. Anti-inflammatory

Isolated arbutin suppresses lipopolysaccharide-induced nitric oxide, iNOS, COX-2, TNF-α, IL-1β and IL-6 in murine BV2 microglial cells via inhibition of NF-κB signalling ^{11Reference 11Lee et al. · 2012In vitroAnti-inflammatory effects of arbutin in lipopolysaccharide-stimulated BV2 microglial cells — in vitro studyView study →}, and leaf extract lowers pro-inflammatory cytokines (IL-1β, IL-6, IL-8, TNF-α) in C. acnes-stimulated keratinocytes ^{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 →}. Older murine work found that the 50% methanolic leaf extract and arbutin both had a therapeutic effect on contact-dermatitis-type immuno-inflammation and potentiated prednisolone and dexamethasone without the corticosteroids’ thymus/spleen atrophy ^{12,13Reference 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 →}. The triterpene ursolic acid contributes NF-κB-linked anti-inflammatory activity of its own.

Gap: the signal is real but entirely preclinical and largely at the level of the isolated constituent; no whole-leaf human anti-inflammatory data exist, and doses used in cell models exceed what the urinary route delivers to non-renal tissue.

4. Skin depigmenting (anti-tyrosinase)

Arbutin is one of the best-characterised natural tyrosinase inhibitors and a widely used cosmetic skin-lightening agent; it competitively inhibits tyrosinase and reduces melanin synthesis in human melanoma cells and α-MSH-stimulated models ^{14,15Reference 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 →}, and the anti-tyrosinase fraction of uva-ursi leaf itself has been isolated ^{16Reference 16Matsuo et al. · 1997In vitroAnti-tyrosinase activity constituents of Arctostaphylos uva-ursi — in vitro studyView study →}. This underpins the traditional use of the leaf for hyperpigmentation. The crucial limiter is preparation match: this activity is established for arbutin applied topically as a purified cosmetic ingredient, not for the leaf taken internally as a urinary remedy — and the same melanin-inhibiting property is implicated in a harm, a bilateral bull’s-eye maculopathy after three years of oral use ^{17Reference 17Wang et al. · 2004Case reportBull’s-eye maculopathy secondary to herbal toxicity from uva ursi — case reportView study →}.

Gap: the depigmenting evidence belongs to isolated topical arbutin, not to bearberry as it is actually used; capped accordingly, and its systemic version is a safety signal, not a benefit.

5. Diuretic

Bearberry is listed as a diuretic in traditional and pharmacopoeial sources, but the experimental support is thin. In rats, an aqueous uva-ursi extract raised urine flow, yet — unlike Orthosiphon or Sambucus in the same study — it did not increase urinary sodium excretion, so it is at best a weak aquaretic ^{18Reference 18Beaux et al. · 1999AnimalEffect of extracts of Orthosiphon stamineus, Hieracium pilosella, Sambucus nigra and Arctostaphylos uva-ursi in rats — animal diuresis studyView study →}. A 2025 study attributes a diuretic action of isolated arbutin to inhibition of aldosterone synthase, but again in rodents and at injected doses ^{19Reference 19Nazeer et al. · 2025AnimalToxicological profiling and diuretic potential of arbutin via aldosterone synthase gene inhibition — rat studyView study →}.

Gap: a single whole-leaf rat study without natriuresis plus a constituent-level rodent mechanism; no human diuresis data, and the effect is modest where measured.

6. Nephroprotective (arbutin)

A cluster of recent rodent studies reports that isolated arbutin protects the kidney: it attenuated LPS-induced acute kidney injury by dampening inflammation and apoptosis through the PI3K/Akt/Nrf2 axis ^{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 →}, and reduced damage in renal ischaemia-reperfusion in a dose-related manner ^{21Reference 21Sirinyildiz et al. · 2025AnimalArbutin as a potential nephroprotective agent — dose-related effects in renal ischaemia-reperfusion (rat model)View study →}. Mechanistically these fit arbutin’s antioxidant/anti-inflammatory profile.

Gap: this is constituent-level, animal-only work on injury models unrelated to bearberry’s traditional urinary-antiseptic use; it does not establish that drinking the leaf protects human kidneys, and free hydroquinone’s own renal safety must be weighed against it.

7. Bladder anti-proliferative

Arbutin decreased proliferation of TCCSUP human bladder-carcinoma cells in a concentration- and time-dependent way, arresting the cell cycle via ERK inactivation and up-regulation of p21 ^{22Reference 22Li et al. · 2011In vitroArbutin inhibits TCCSUP human bladder-cancer cell proliferation via up-regulation of p21 — in vitro studyView study →}. Because arbutin’s hydroquinone metabolite concentrates in the bladder, the tissue context is at least plausible. A separate proteomic study, though, used the same target cell to characterise hydroquinone’s cytotoxicity and prooxidant stress at therapeutic-equivalent doses — the flip side of the same chemistry ^{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 →}.

Gap: one cell line, one constituent, no in vivo or human data; and the closely related toxicity findings mean any “anticancer” reading is premature.

Mechanisms

Mechanism	Drives	Key compounds
Arbutin → β-glucosidase hydrolysis → hydroquinone → hepatic conjugation → renal excretion of free HQ in (alkaline) urine	antibacterial / urinary antiseptic	arbutin, hydroquinone, methylarbutin
NF-κB ↓, COX-2 ↓, iNOS ↓, TNF-α/IL-1β/IL-6 ↓	anti-inflammatory	arbutin, ursolic acid
Tyrosinase competitive inhibition → melanin synthesis ↓	skin depigmenting	arbutin, methylarbutin
Radical scavenging, ferric reduction, Nrf2 activation	antioxidant, nephroprotective	quercetin, myricetin, gallotannins
Hydrolysable-tannin protein precipitation (astringency)	astringent / urinary-tract tonifying	gallotannins, gallic acid, ellagic acid
ERK inactivation, p21 up-regulation	bladder anti-proliferative (in vitro)	arbutin

Clinical trials

Bearberry is one of the few single herbs with placebo-controlled UTI trials: two are complete (ATAFUTI and REGATTA/Gágyor, both null-to-mixed on efficacy), a human pharmacokinetic RCT confirms urinary delivery of hydroquinone, and a fosfomycin non-inferiority trial (BRUMI) is recruiting; no trials have been terminated, and the remainder of the evidence is preclinical ^{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 →}.

Completed	Planned	Terminated	Preclinical
3	1	0	~40

Last checked: July 2026.

Pharmacodynamics

Arbutin, one of the main components of bearberry (a phenolic glycoside), is hydrolyzed in the intestines to hydroquinone, absorbed, and metabolized where it’s excreted in the urine. ^{34,35Reference 34Hansel R et al. · 1999Berlin: Springer-VerlagReference 35Siegers C et al. · 2003Bacterial deconjugation of arbutin by Escherichia coli}.

Dosage

In research, bearberry is almost always given as a standardised dry extract titrated to a set arbutin dose, not as a measured amount of whole leaf. The doses below are the amounts used in the clinical and pharmacokinetic studies — they are research doses, not recommendations.

Indication	Preparation	Dose	Est. dried-herb equivalent	Source
Uncomplicated UTI / cystitis	Standardised dry-extract tablet (arbutin)	105 mg arbutin × 3 daily, 2 tablets each (≈ 630 mg arbutin/day) for 5 days	~3.5–9 g dried leaf/day	1
Uncomplicated UTI (symptom trial)	Uva-ursi dry extract (ATAFUTI)	Per product label, 5 days	Proprietary — no marker % stated	2
Urinary antiseptic (pharmacokinetics)	Dry extract, arbutin-standardised	Commission E equivalent: 400–840 mg hydroquinone derivatives (as anhydrous arbutin)/day	≈ 3–12 g dried leaf/day	3, 4

Est. dried-herb equivalent is a rough back-conversion on the stated assumption “dried bearberry leaf ≈ 7–17% arbutin” (European Pharmacopoeia min. 7%). It is a guide only, not a dosing recommendation or a fixed conversion factor; the proprietary ATAFUTI extract gives no marker %, so its equivalent is left unquantified.

Traditional Dosage

Western herbal practice uses the whole leaf as a cold infusion (cold maceration is preferred to preserve arbutin and lower the tannin load), a tincture, or a liquid extract. These traditional whole-herb doses are not interchangeable with the standardised-extract research doses above.

System	Preparation	Dose
Western herbal	Dried-leaf infusion (cold macerate preferred)	1.5–4 g leaf, up to 3× daily
Western herbal	Liquid extract (1:1)	1.5–4 mL, up to 3× daily
Western herbal	Tincture (1:5)	5–10 mL, up to 3× daily

Safety

Bearberry is for short-term use only — the standard limit is up to 5 consecutive days and no more than 3 courses per year — because its active principle, arbutin, delivers free hydroquinone to the urine, and hydroquinone is cytotoxic and prooxidant to bladder cells at high concentrations and is a theoretical carcinogen ^{8,23Reference 8de Arriba et al. · 2013ReviewRisk assessment of free hydroquinone derived from Arctostaphylos uva-ursi folium herbal preparations — reviewView study →Reference 23Huđek Turković et al. · 2022In vitroProteome changes in human bladder T24 cells induced by hydroquinone derived from Arctostaphylos uva-ursi — in vitro studyView study →}. At recommended doses a regulatory risk assessment estimated maximum urinary free-hydroquinone exposure at ~11 µg/kg/day, well below the level of concern, so acute therapeutic use is considered low-risk ^{8Reference 8de Arriba et al. · 2013ReviewRisk assessment of free hydroquinone derived from Arctostaphylos uva-ursi folium herbal preparations — reviewView study →}. Prolonged oral use is a documented harm: three years of daily uva-ursi caused bilateral bull’s-eye maculopathy (retinal damage), attributed to arbutin’s inhibition of melanin synthesis ^{17Reference 17Wang et al. · 2004Case reportBull’s-eye maculopathy secondary to herbal toxicity from uva ursi — case reportView study →}. The leaf’s high tannin content can cause nausea and gastric irritation, and cold-water infusion is preferred to reduce tannin extraction. Bearberry should not be combined with agents or foods that acidify the urine, since hydroquinone liberation and antibacterial activity fall in acidic urine. Because it is a urinary antiseptic and not a proven cure, clinical trials found it inferior to antibiotics for cystitis, with more persistent symptoms and more progression to pyelonephritis — it should not replace antibiotics where an infection is established ^{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 →}.

Bearberry is also contraindicated in children under 12, and in people with kidney disorders.

Scope of the evidence. No formal drug-interaction (CYP450 or transporter) trials have been done; the one interaction with mechanistic support is pharmacodynamic, not pharmacokinetic — urine-acidifying substances (and possibly high vitamin-C intake) reduce hydroquinone liberation and the antibacterial effect. The reported antibacterial synergy with β-lactams (corilagin/tellimagrandin I) is in vitro only. Pregnancy, lactation and paediatric safety were not studied; the contraindications below are precautionary, not evidence of demonstrated harm.

Pregnancy & lactation

Avoid. Bearberry is contraindicated in pregnancy and lactation. It has not been assessed in controlled human pregnancy studies; the concern is mechanistic — hydroquinone is genotoxic/cytotoxic in vitro and crosses biological membranes, and an early screen reported uterotonic (oxytocic) activity for uva-ursi extract — so it should not be used during pregnancy or breastfeeding, and is also contraindicated in children under 12. Safety here rests on absence of evidence plus a plausible hazard, not on demonstrated harm to a fetus.

Synergy

Traditionally paired with dandelion root or leaf as a diuretic combination. A more evidence-based synergy note is the in vitro finding that bearberry’s ellagitannins corilagin and tellimagrandin I potentiate β-lactam antibiotics against MRSA ^{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 →} — though this remains a laboratory result, not a clinical protocol.

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/
6. Deutch, C. E. (2017). Limited effectiveness of over-the-counter plant preparations against the urease of Staphylococcus saprophyticus — in vitro study. Journal of Applied Microbiology. https://pubmed.ncbi.nlm.nih.gov/28245081/
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/
8. de Arriba, S. G., et al. (2013). Risk assessment of free hydroquinone derived from Arctostaphylos uva-ursi folium herbal preparations — review. International Journal of Toxicology. https://pubmed.ncbi.nlm.nih.gov/24296864/
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/
11. Lee, H. J., & Kim, K. W. (2012). Anti-inflammatory effects of arbutin in lipopolysaccharide-stimulated BV2 microglial cells — in vitro study. Inflammation Research. https://pubmed.ncbi.nlm.nih.gov/22487852/
12. Kubo, M., et al. (1990). Pharmacological studies on leaf of Arctostaphylos uva-ursi I — combined effect of methanolic extract and prednisolone on immuno-inflammation in mice (animal model). Yakugaku Zasshi. https://pubmed.ncbi.nlm.nih.gov/1693958/
13. Matsuda, H., et al. (1990). Pharmacological study on Arctostaphylos uva-ursi II — combined effects of arbutin and prednisolone or dexamethasone on immuno-inflammation in mice (animal model). Yakugaku Zasshi. https://pubmed.ncbi.nlm.nih.gov/2355310/
14. Boo, Y. C. (2021). Arbutin as a skin-depigmenting agent with antimelanogenic and antioxidant properties — review. Antioxidants. https://pubmed.ncbi.nlm.nih.gov/34356362/
15. Sugimoto, K., et al. (2004). Inhibitory effects of α-arbutin on melanin synthesis in cultured human melanoma cells and a three-dimensional human skin model — in vitro study. Biological & Pharmaceutical Bulletin. https://pubmed.ncbi.nlm.nih.gov/15056856/
16. Matsuo, K., et al. (1997). Anti-tyrosinase activity constituents of Arctostaphylos uva-ursi — in vitro study. Yakugaku Zasshi. https://pubmed.ncbi.nlm.nih.gov/9437910/
17. Wang, L., & Del Priore, L. V. (2004). Bull’s-eye maculopathy secondary to herbal toxicity from uva ursi — case report. American Journal of Ophthalmology. https://pubmed.ncbi.nlm.nih.gov/15183807/
18. Beaux, D., et al. (1999). Effect of extracts of Orthosiphon stamineus, Hieracium pilosella, Sambucus nigra and Arctostaphylos uva-ursi in rats — animal diuresis study. Phytotherapy Research. https://pubmed.ncbi.nlm.nih.gov/10353162/
19. Nazeer, M., et al. (2025). Toxicological profiling and diuretic potential of arbutin via aldosterone synthase gene inhibition — rat study. Life Sciences. https://pubmed.ncbi.nlm.nih.gov/40280300/
20. Zhang, B., et al. (2021). Arbutin attenuates LPS-induced acute kidney injury by inhibiting inflammation and apoptosis via the PI3K/Akt/Nrf2 pathway — rat study. Phytomedicine. https://pubmed.ncbi.nlm.nih.gov/33494001/
21. Sirinyildiz, F., et al. (2025). Arbutin as a potential nephroprotective agent — dose-related effects in renal ischaemia-reperfusion (rat model). Biomolecules and Biomedicine. https://pubmed.ncbi.nlm.nih.gov/40963362/
22. Li, H., et al. (2011). Arbutin inhibits TCCSUP human bladder-cancer cell proliferation via up-regulation of p21 — in vitro study. Die Pharmazie. https://pubmed.ncbi.nlm.nih.gov/21612160/
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/
25. Tóth, B., et al. (2022). Bearberry in the treatment of acute uncomplicated cystitis (BRUMI) — protocol of a multicentre randomised double-blind clinical trial. BMJ Open. https://pubmed.ncbi.nlm.nih.gov/35750460/
26. Panusa, A., et al. (2015). UHPLC-PDA-ESI-TOF/MS metabolic profiling of Arctostaphylos pungens and A. uva-ursi — a comparative study of leaf phenolics (species-adulteration relevance). Phytochemistry. https://pubmed.ncbi.nlm.nih.gov/25702282/
27. Samoilova, Z., et al. (2014). Medicinal plant extracts can variously modify biofilm formation in Escherichia coli — in vitro study. Antonie van Leeuwenhoek. https://pubmed.ncbi.nlm.nih.gov/24500005/
28. Shiota, S., et al. (2004). Mechanisms of action of corilagin and tellimagrandin I that potentiate β-lactams against methicillin-resistant Staphylococcus aureus — in vitro study. Microbiology and Immunology. https://pubmed.ncbi.nlm.nih.gov/14734860/
29. British Herbal Medicine Association. (1983). British Herbal Pharmacopoeia. Bournemouth, UK: Author.
30. Hoffmann, D. (2003). Medical herbalism: The science and practice of herbal medicine. Rochester, VT: Healing Arts Press.
31. Wren, R. C. (1968). Potter’s new cyclopaedia of botanical drugs and preparations. Rustington, Sussex: Health Science Press for Potter & Clarke.
32. Small, E., & Catling, P. M. (1999). Canadian medicinal crops. Ottawa: NRC Research Press. http://site.ebrary.com/id/10006178
33. Bone K, Mills S. (2013). Principles and Practice of Phytotherapy. Elsevier health. China. (Pg. 392-398).
34. Hansel R, Sticher O, Steinegger E. Pharmakognosie-Phytopharmazie. (1999). Berlin: Springer-Verlag.
35. Siegers C, Bodinet C, Ali SS, Siegers CP. (2003). Bacterial deconjugation of arbutin by Escherichia coli. Phytomedicine 2003;10:58–60.