IngredientsArctostaphylos (from the Greek árktos, "bear," and staphulḗ, "bunch of grapes") is a genus of plants within the family Ericaceae, many members of which are commonly called manzanitas or bearberries. The common name "manzanita" derives from the Spanish for "little apple," referring to the small rounded fruit, which is often green or in various shades of red.
Virtually all of the 107 or so recognized species and subspecies in the genus are native to the California Floristic Province, making manzanitas a quintessential part of the region's natural heritage. One species, however, A. uva-ursi (common bearberry), is adapted to arctic and subarctic climates and has a circumpolar distribution in northern North America, Asia and Europe.
Arctostaphylos is a genus of woody, evergreen shrubs or small trees native primarily to western North America, from southern British Columbia into Mexico. Because of the wide geographic distribution, the habit of manzanitas varies widely from prostrate, wide-spreading groundcovers to rounded shrubs to small trees; the larger-growing plants often have intricately twisted branches enhanced by a beautiful, polished mahogany-like bark.
The most medicinally significant species within the genus, and the one underpinning the majority of formal scientific investigation and regulatory review, is Arctostaphylos uva-ursi (L.) Spreng., known as bearberry or uva-ursi. Bearberry is a common name for manzanitas, and for A. uva-ursi in particular — the same phrase in three languages for genus, species, and common name. Other species with documented ethnobotanical use include A. manzanita (whiteleaf manzanita), A. pungens (pointleaf manzanita), A. glauca (bigberry manzanita), and A. columbiana (hairy manzanita), among many others.
Manzanitas are members of the heath family, the Ericaceae. From prostrate shrubs to small erect trees, Arctostaphylos is known for characteristic red bark, urn-shaped flowers, and being fire-adapted. In late winter to early spring, manzanitas bear delicate, urn-shaped flowers — pale pink to white and honey-scented — that resemble those of their Arbutus relatives.
The plant parts used medicinally vary by tradition and by species. In the context of formal herbal medicine, for natural medicinal health purposes, only the leaves, not the berries, are used in herbal medicine in the case of A. uva-ursi. More broadly across Arctostaphylos species, the berries, leaves, bark, and the green inner bark layer have all been employed in different traditional contexts.
Modern commercial preparations of the medicinally recognized species (A. uva-ursi) include:
Uva ursi leaf was listed on the U.S. National Formulary as a urinary antiseptic from 1820 to 1950, but it is no longer listed in the United States Pharmacopoeia. Uva ursi has been used extensively in native cultures since the Middle Ages and is listed in the pharmacopoeias of many Western societies for the treatment of urinary conditions, primarily symptoms of urinary tract infection.
Manzanita (Arctostaphylos spp.) has a long history of use among Indigenous peoples of North America, particularly in California, where its berries and leaves have been utilized for nutritional and medicinal purposes. Traditionally, manzanita berries were consumed fresh or dried, ground into meal, or steeped to make beverages, while the leaves were sometimes used in topical preparations or infusions believed to support urinary tract health.
The berries of manzanitas, often reddish when ripe, are edible, traditionally gathered by Native Americans, and are a favored food for bears. Native Americans used the plant for food; leaves were used for smoking, berries were eaten raw or ground into a meal for porridge, and cider and jelly were made from the berries.
The plant was used widely by Native Americans in the southwest. In general, the berries were collected when ripe and eaten raw. Manzanita berries were also cooked into beverages or jellies for later use. The Cahuilla people of the Palm Springs area picked fresh pointleaf manzanita (A. pungens) berries and ate them raw.
Throughout the Californias, native peoples used the fruit of manzanita shrubs to make a drink; many Kumeyaay still gather the fruits for this purpose. The leaves were also made into a tonic for kidney ailments.
Native American tribes of California and the Southwest have used Arctostaphylos manzanita for centuries. The Miwok people, for example, prepared a mild tea from the leaves to relieve urinary discomfort and low-grade fevers. Some of the Native American tribes in Northern California make an infusion from the manzanita leaves and drink it to cure poison oak rash.
Native Americans use the fresh berries to make cider and use the leaves as toothbrushes. The plant was also used as a tobacco substitute or additive. A strong decoction of manzanita leaves, applied warm externally, was used to treat poison ivy and oak, rashes, and shingles. Berries and leaves were used to relieve bronchitis, kidney ailments, dropsy, and female disorders.
Grown throughout Asia, North America, and Europe, uva ursi has a long history of medicinal use dating back to the 13th century. The leaves have been used worldwide as a diuretic, astringent, antiseptic, and a treatment for urinary tract infections. A tea brewed with the leaves has also been used as a laxative.
Uva ursi has been used to treat dysuria, cystitis, urethritis, and kidney and bladder stones. It has also been recommended for inducing diuresis and to treat constipation. In addition, the leaves of Arctostaphylos have been dried and smoked as tobacco, while leaves and berries have also been used as food.
Manzanita has a history of traditional use among various Indigenous peoples of Western North America to treat inflammation and related conditions. The leaves and berries have been used in decoctions, poultices, and teas as remedies for skin inflammation, urinary tract irritation, and mouth sores.
Leaf infusions were commonly prepared as a soothing wash for skin irritations, minor cuts, and poison oak rashes. When brewed as a tea, manzanita leaves were consumed to alleviate urinary tract infections, kidney-related issues, and as a mild diuretic.
The tea from the leaves also acts as a mild vasoconstrictor for the uterus and therefore can be helpful during painful and heavy menstruation. However, herbalist Michael Moore does not advise its use during pregnancy.
The medicinal phytochemistry of manzanita has been most thoroughly characterized in A. uva-ursi, which serves as the scientific reference standard for the genus.
Arctostaphylos uva-ursi leaves contain high levels of phenolic compounds, particularly arbutin, the principal bioactive constituent responsible for the biological activity of bearberry preparations. Arbutin may undergo hydrolysis to hydroquinone, a redox-active compound modulating cellular oxidative balance.
The active component of the extract is arbutin, a hydroquinone glycoside, which accounts for 5–16% of dried Arctostaphylos uva-ursi leaves. The primary chemical component of uva ursi is arbutin or hydroquinone-O-beta-D-glucose (5% to 16%); the arbutin content varies seasonally.
The most representative constituent of this herbal drug is arbutin, which is rapidly absorbed in the small intestine and undergoes hepatic conjugation to form hydroquinone (HQ) conjugates. When broken down by the body, arbutin forms hydroquinone. Hydroquinone is an antibiotic that is directly excreted through the urinary tract and therefore does not have undesired effects on the microbes of the intestines, but instead has a direct action on any microbes in the bladder and urethra.
Quantitative phytochemical analyses have confirmed notable variability in arbutin content across populations and extraction methods. In a study examining twelve A. uva-ursi sites, water extracts from bearberry leaves were characterized by arbutin concentrations of 77.64–105.56 mg g⁻¹ and hydroquinone concentrations of 6.96–13.08 mg g⁻¹, compared with ethanol extracts yielding 77.21–103.38 mg g⁻¹ arbutin and 10.55–16.72 mg g⁻¹ hydroquinone.
A. uva-ursi contains a steroid, sitosterol, and triterpenoids such as amyrin, betulinic acid, lupeol, oleanolic acid, taraxenol, ursolic acid, and uvaol. The main constituent is a glucoside called arbutin; other constituents are methylarbutin, ericolin, ursone, gallic acid, and additional polyphenols.
The chemical profile of bearberry leaves is characterized by the presence of ursolic acid, tannic acid, gallic acid, p-coumaric acid, syringic acid, galloylarbutin, gallotannins, and glycosidic forms of flavonoids, e.g., quercetin, kaempferol, and myricetin glycosides, penta-O-galloyl-β-d-glucose, hyperoside, corilagin, and picein.
Arctostaphylos uva-ursi contains hydrolysable tannins. These tannins, when ingested, bind to and precipitate proteins, producing an astringent action on mucosal tissues, which forces their dehydration. Hydrolysable tannins also show antioxidant and free-radical scavenging activity.
Uva ursi leaves contain several phytochemicals, including ursolic acid, tannic acid, gallic acid, oils, resins, hydroquinone glycosides (mainly "arbutin"), and flavonoids. Ursolic acid is a pentacyclic triterpenoid that has been the subject of independent investigation for anti-inflammatory and antioxidant properties. Findings from both animal and in vitro studies suggest that ursolic acid decreases inflammatory cytokine levels, elevates antioxidant enzyme levels, and reduces oxidative stress levels. There is currently evidence suggesting that ursolic acid may exert a favorable influence on both anti-inflammatory and antioxidant impact.
The extract constituents include flavonoids, iridoids, hydroquinone glycosides (mainly arbutin), tannins, and terpenoids. Identified flavonoids include quercetin, kaempferol, and myricetin glycosides, as well as hyperoside and corilagin. Astringent and antibacterial properties of corilagin may contribute to the impact of uva ursi on urinary tract infections and other infections.
Chemical profiling studies suggest meaningful variation among Arctostaphylos species. Some contain lower arbutin than classic medicinal bearberry leaf, while differing in flavonols, galloyl compounds, and other phenolics. In order to discriminate between Arctostaphylos pungens and Arctostaphylos uva-ursi, a morphologically similar plant with lower arbutin content, a UHPLC-PDA-ESI-TOF/MS fingerprinting method was applied on the methanolic leaf extracts.
The active component of uva ursi is suspected to be hydroquinone, and particularly arbutin and methyl arbutin, which may have anti-inflammatory and antiseptic activities that are excreted in the urine. According to Michael Moore, author of Medicinal Plants of the Mountain West, the leaves of all species contain arbutin, a glycoside that is broken down to hydroquinone in the urine, which is the reason that manzanita leaf tea has disinfectant qualities.
In-vitro studies have demonstrated antibacterial activity against a variety of organisms including Escherichia coli, the most prevalent urinary pathogen. The antimicrobial action has been attributed to the hydroquinone derivatives, especially arbutin. Laboratory experiments have further shown antibacterial activity of arbutin against Pseudomonas aeruginosa and Chromobacterium violaceum, and a bacteriostatic and anti-motility effect against Escherichia coli. They also inhibit Gram-positive bacteria such as Staphylococcus aureus and Staphylococcus saprophyticus, and the pathogenic yeast Candida albicans.
The leaves and berries have been used in decoctions, poultices, and teas as remedies for skin inflammation, urinary tract irritation, and mouth sores. The anti-inflammatory effects are primarily attributed to the presence of compounds such as arbutin, tannins, and flavonoids, which may have mild astringent and antimicrobial properties.
Arbutin involves a depigmenting mechanism in human skin through inhibition of melanosomal tyrosinase, rather than suppression of the expression and synthesis of tyrosinase. This mechanism has made arbutin — and by extension, bearberry/manzanita leaf extract — a subject of interest in cosmetic dermatology for skin-lightening applications.
Reviews of the experimental work on the inhibition of microbial growth by Uva ursi extracts and their components describe complementary studies on the effects of these extracts on two key virulence factors, the enzyme urease and the ability of microbes to form biofilms, as well as antioxidant and anti-inflammatory properties of these extracts and their effects on other host functions.
Research suggests that the herb's anti-infective activities are most effective when urine is alkaline, as acidity reduces its antibacterial properties.
Evidence strength: Weak to moderate for symptom relief; insufficient for treatment of established infection.
For many years, leaves of this plant have been used in traditional medicine as a diuretic, antimicrobial, and anti-inflammatory agent for various diseases of the urogenital tract. The ESCOP monograph includes studies with its main characteristic constituents arbutin and methylarbutin, and the therapeutic indications are uncomplicated infections of the lower urinary tract.
The most rigorous human trial is the ATAFUTI study. The ATAFUTI study is the first double-blind, placebo-controlled, factorial randomised trial to investigate a traditional herbal medicinal product as an alternative treatment for UTIs in women, with the aim of reducing symptoms and reducing antibiotic consumption in primary care. It was a 2×2 factorial placebo-controlled randomized trial in primary care. The participants were 382 women aged 18–70 years with symptoms of dysuria, urgency, or frequency of urination and suspected by a clinician to have a lower UTI. An intention-to-treat (ITT) analysis of mean score for frequency symptoms assessed on days 2–4 found no evidence of a difference between uva-ursi vs. placebo (−0.06; 95% CI −0.33 to 0.21; p = 0.661), nor ibuprofen vs. no ibuprofen advice (−0.01; 95% CI −0.27 to 0.26; p = 0.951).
A separate German trial, the REGATTA study, was designed as a double-blind, randomized, and controlled comparative effectiveness trial. Its main research questions were: does initial treatment with uva-ursi in women with uncomplicated UTI reduce the number of antibiotic courses without significantly increasing symptom burden, and is the suggested strategy safe with regard to complications and recurrences? Women between 18 and 75 years with suspected UTI and at least two of the symptoms of dysuria, urgency, frequency, or lower abdominal pain were assessed for eligibility in general practice and enrolled into the trial.
Overall, although the laboratory data indicate that Uva ursi preparations can effectively inhibit urinary tract pathogens and so may represent an alternative to antibiotics, the clinical studies are far more limited and currently insufficient to justify their widespread medical use. While uva ursi has been used extensively in traditional medicine, there is no convincing medical evidence that it is effective in treating urinary tract infections or urinary symptoms.
Evidence strength: Preliminary; only one small older RCT with positive signal.
In 1993, a preliminary report found that an extract of uva-ursi had a preventative effect on recurrent cystitis in women, concluding that it significantly reduced the number of recurrent infections compared to a placebo without causing side effects (Larsson et al., 1993). Clinical trials haven't confirmed the ability of uva ursi to treat UTIs, but it may prevent them.
Evidence strength: Preliminary; mainly in vitro.
Reviews summarize the experimental work on the inhibition of microbial growth by Uva ursi extracts and their components, including complementary studies on the effects of these extracts on the enzyme urease and the ability of microbes to form biofilms. In vitro studies demonstrate broad-spectrum antibacterial and antifungal activity, but human clinical data confirming these mechanisms in vivo are lacking.
Evidence strength: Mechanistically plausible; clinical evidence mixed and largely cosmetic-context.
Arctostaphylos uva-ursi leaf extracts are characterized by antioxidant and antimicrobial activity and have been used as skin-whitening agents and antioxidant agents in food and food packaging formulations. The depigmenting mechanism via tyrosinase inhibition by arbutin is well-characterized at the molecular level, but clinical trial data on manzanita-specific formulations are limited.
Evidence strength: Preliminary; in vitro only.
The effective antibacterial activity associated with a powerful anti-inflammatory action suggested that Arctostaphylos uva-ursi could represent a promising source for the treatment of acne vulgaris, based on in vitro studies against Cutibacterium acnes. No human clinical trials on manzanita for acne have been identified in peer-reviewed literature.
Evidence strength: Preliminary; primarily in vitro and animal studies for manzanita specifically.
Laboratory analyses have identified compounds such as arbutin and tannins in manzanita leaves, which may contribute to observed health effects. Although direct clinical studies on manzanita's health benefits in humans are limited, more research is needed to validate specific health claims. The constituent ursolic acid has been evaluated more broadly: findings from both animal and in vitro studies suggest that ursolic acid decreases inflammatory cytokine levels, elevates antioxidant enzyme levels, and reduces oxidative stress levels, and a meta-analysis has furnished compelling evidence for the anti-inflammatory and antioxidant properties of ursolic acid. These findings do not, however, derive from manzanita-specific clinical trials.
Evidence strength: Very preliminary; limited clinical data.
Arbutin alone has been reported to relieve pain from kidney stones, cystitis, and nephritis. Its potential to help with kidney stones, allergies, and high blood pressure was tested in animal and cell-based studies only.
Evidence strength: Traditional and pharmacological plausibility; limited formal clinical evidence.
Uva ursi extract is reported to have diuretic, urinary antiseptic, astringent, and anti-inflammatory properties. Herbalist Michael Moore suggests leaf tea in cases of mild urinary tract infections, chronic kidney inflammations, and water retention. Formal controlled clinical evidence for a diuretic effect in humans is not established in the peer-reviewed literature reviewed here.
Based on documented traditional use and the scientific literature, manzanita is primarily associated with the following body systems:
Formal dosage information applies primarily to Arctostaphylos uva-ursi leaf preparations, as reviewed by official monographs. Because "manzanita" covers many species, there is no single modern dosage that cleanly applies to the whole genus. The most responsible dosage guidance comes from the better-studied Arctostaphylos uva-ursi leaf monograph, which is often used as the reference point for medicinal Arctostaphylos leaf use. Any dose advice for generic manzanita should be treated as cautious extrapolation, not as a universal rule for every species.
Reports of carcinogenicity of hydroquinone after prolonged administration of high doses to rats or mice raise a question about the long-term safety of A. uva-ursi and other medicinal herbs that contain substantial amounts of arbutin. However, a formal risk assessment reviewed this concern in detail. A therapeutic recommended human daily dose of bearberry leaf extract (420 mg hydroquinone derivatives calculated as anhydrous arbutin) liberates free HQ in urine at a maximum exposure level of 11 µg/kg body weight (bw)/d. By means of an experimental no observed effect level value, a permitted daily exposure dose below which there is a negligible risk to human health was estimated for free HQ (100 µg/kg bw/d). There is no direct evidence, regarding human data, supporting the fact that free HQ causes convulsion, hepatotoxicity, nephrotoxicity, or promotion of tumors in humans. Free HQ had no activity promoting pancreatic, bladder, stomach, or liver carcinogenesis. In conclusion, under the recommended use conditions, Uva-ursi folium is a safe therapeutic option for treating lower urinary tract infections.
Due to its high tannin content, uva ursi may cause acute nausea and intestinal irritation.
Both water and ethanolic extracts exhibited pronounced concentration- and time-dependent cytotoxicity toward BJ fibroblasts. At higher concentrations, cell viability decreased markedly, and the effect intensified after prolonged exposure. This behavior is consistent with the activity of hydroquinone, which induces oxidative stress, mitochondrial dysfunction, and loss of metabolic activity in fibroblasts. The progressive decrease in viability between 24 h and 48 h observed in experiments further supports cumulative oxidative damage as the primary mechanism of toxicity.
A 57-year-old woman who ingested uva ursi tea preparations several times daily for 3 years developed "bull's eye" maculopathy, which is typical of hydroxychloroquine macular injury, suggesting that hydroquinone from uva ursi — which inhibits tyrosine kinase and melanin synthesis — can cause macular injury as well. This case report highlights the risk of long-term, high-frequency use.
Uva ursi has not been linked to serum enzyme elevations during therapy, although there have been few prospective studies of its adverse effects on laboratory test results. There have been no convincing published instances of clinically apparent liver injury attributed to uva ursi. The NIH LiverTox database assigns it a likelihood score of E (unlikely cause of clinically apparent liver injury).
Herbalist Michael Moore does not advise its use during pregnancy, consistent with formal regulatory guidance. No data exist on the excretion of any components of uva ursi into breastmilk, or on the safety and efficacy of uva ursi in nursing mothers or infants. Uva ursi should generally be avoided during breastfeeding because of a lack of data and its potential toxicity, per the NIH Drugs and Lactation Database (LactMed).
Research has identified potential pharmacokinetic interactions. A 2018 study characterized identification and characterization of in vitro inhibitors against UDP-glucuronosyltransferase 1A1 in uva-ursi extracts and evaluation of in vivo uva-ursi–drug interactions (Park JB et al., Food Chem Toxicol, 2018), raising the possibility of interactions with drugs metabolized by UGT1A1, though this has not been thoroughly characterized in human clinical studies.
The European Union herbal monograph on Arctostaphylos uva-ursi specifies the preparation is not to be used for more than one week. These studies have shown that these extracts are relatively safe, although the key component arbutin can be metabolized to form the more toxic compound hydroquinone.
Hydroquinone can be found in leaves or be formed by degradation of arbutin. The analysis of different samples of bearberry leaves by a stability-indicating HPLC method evidenced high variation in arbutin and hydroquinone levels, demonstrating the need for standardization.
The leaf extract of Arctostaphylos uva-ursi has been approved for use for urinary tract inflammation by the German Federal Institute for Drugs and Medical Devices and is available on prescription in Germany for this indication. The ESCOP monograph published in 2012 recognizes uncomplicated infections of the lower urinary tract as the therapeutic indication. The WHO has published a monograph on the leaf (Folium Uvae Ursi) in its WHO Monographs on Selected Medicinal Plants, Volume 2. Uva ursi leaf was listed on the U.S. National Formulary as a urinary antiseptic from 1820 to 1950, but it is no longer listed in the United States Pharmacopoeia.
Health conditions that Manzanita may help support.
Body systems that Manzanita may help support.
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