Bayberry

Bayberry (Myrica spp.): A Comprehensive Reference

1. Identity and Botanical Classification

Bayberry is the common name applied to several species within the genus Myrica L. (family Myricaceae, order Fagales), of which the two most medicinally studied are Myrica cerifera L. (southern wax myrtle, American bayberry) and Myrica rubra (Lour.) Siebold & Zucc. (Chinese bayberry, red bayberry). The genus Myrica comprises approximately 97 species, including M. gale (Sweet Gale or Bog Myrtle), M. cerifera (Wax Myrtle), M. esculenta (Bayberry or Kafal), M. rufa (Rufa Bayberry), M. coriacea (Coriaceous Bayberry), and M. faya (Faya Tree), found in different countries worldwide. Scientific names applied to medicinal bayberry include Myrica cerifera L. and Myrica rubra (Lour.) Siebold and Zucc., with common names such as Bayberry, Candleberry, Chinese bayberry, Red bayberry, Tallow shrub, Wax myrtle, Waxberry, and Yang-mei.

Occasionally, the genus is divided into two genera, Myrica and Morella, with the former restricted to only a few species and the remainder appearing under Morella. Accordingly, M. cerifera is sometimes listed as Morella cerifera (L.) Small, and M. rubra as Morella rubra Lour., the latter appearing in some recent botanical databases and research literature. The generic name Myrica comes from a Greek word myrike, which refers to some fragrant plant, possibly tamarisk.

1.1 Botanical Description

The most medicinally recognized North American species, Myrica cerifera, grows in thickets near swamps and marshes in the sand-belt near the Atlantic coast and on the shores of Lake Erie. Its height is from 3 to 8 feet, its leaves lanceolate, shining or resinous, dotted on both sides, its flowers unisexual without calyx or corolla, and its fruit small groups of globular berries, having numerous black grains crusted with greenish-white wax. These are persistent for two or three years. The leaves are very fragrant when rubbed.

Some species are deciduous, but the majority are evergreen and range in size from 1 m shrubs to 20 m trees. Because the roots contain microorganisms that fix nitrogen, plants may thrive in soils with very little nitrogen. Catkins are the blooms; male and female catkins are often on different plants (dioecious). The fruit is a tiny drupe that frequently has a waxy covering.

Myrica rubra is a subtropical fruit tree that is indigenous to China and other Asian nations, with references to this Myricaceae plant in Chinese history dating back more than 2,000 years. The fruit is delicious with attractive colour, flavour, and high economic value.

1.2 Plant Parts Used and Common Preparations

Basically the bark is used for medicinal purposes, but leaves, wax extracted from the fruits, and fruits can also be used for therapeutic purposes. While the berries were historically used to make candles, the root bark is the primary part used in herbal medicine for its potent astringent, antimicrobial, and circulatory-stimulating properties.

The bark as found in commerce is in curved pieces from 1 to 7 inches long, covered with a thin, mottled layer, the cork beneath being smooth and red-brown. The wax was first introduced into medicinal use by Alexandre in 1722. It is removed from the berries by boiling them in water, on the top of which it floats. It melts at 47 to 49°C (116.6 to 120.2°F). It is harder and more brittle than beeswax.

Bayberry root bark contains tannins, resins, triterpenes, and volatile oils. It is typically administered as a tincture, decoction, or powdered capsule, often in combination with other warming and stimulating herbs such as cayenne or ginger for enhanced effectiveness. In general, either a decoction or a tincture is used. Infusions and a topical paste have also been used.

In the food industry, bayberry is an economically important crop in China, where it is sold fresh, canned, dried, as an alcoholic beverage, or as juice. The wax extract taken from the berries is used in fragrances and candles.

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2. Traditional and Historical Use

2.1 Native American and Indigenous Use

Bayberry was utilized medically by Native Americans. American Indian tribes used the leaves for anthelmintic purposes, the leaves and stems for treating fever, and the roots as a poultice. According to Daniel Moerman's Medicinal Plants of Native America, the branches of sweet gale (Myrica gale) were used by the Bella Coola Indians of British Columbia to prepare decoctions for use as a diuretic or as a treatment for gonorrhea. Other Native American peoples have used bayberry for dysentery, diarrhea, fevers, gynecological conditions, bleeding in the uterus, and as a toothache remedy.

The Choctaw boiled bayberry and used the result as a treatment for fevers. The Mohegans used the tea to treat kidney disorders.

2.2 Early American Colonial and Eclectic Medical Use

The early American colonists did not initially use the herb medicinally, but rather made candles, soaps, and cosmetics from the bayberry fruit. Over time, medicinal use became widespread. In 1722, it was reported that colonists in Louisiana drank a mixture of wax and hot water to treat severe dysentery. Bayberry was reported in an account from 1737 as being used to treat convulsions, colic, palsy, and seizures.

Starting in the early 19th century, the herbalist Samuel Thomson recommended this plant for producing "heat" within the body and as a treatment for infectious diseases and diarrhea. That use of bayberry waned later in the 19th century, in favor of using it for a variety of ailments, including a topical use for bleeding gums.

Bayberry was a cornerstone herb in early American folk medicine and 19th-century Eclectic medicine. Practitioners used it extensively for "cold" conditions, where it was believed to warm the system, arrest discharges, and promote healing. The Shakers and Thomsonian herbalists especially revered bayberry, using it in formulas to stimulate vitality, resolve stagnation, and treat mouth and gum diseases. Bayberry root bark tea was a popular home remedy for sore throats, colds, and internal bleeding.

In deep-seated conditions, Samuel Thomson employed the pungent and astringent bayberry bark (Myrica cerifera), describing it as "the best remedy for canker that I have ever found." He soon also began to use similarly astringent and warming herbs alongside it.

Nineteenth-century physicians used to prescribe a hot tea made from the powdered bark of the bayberry at the first sign of a cold, cough, or flu. The bark appears to be moderately tonic and astringent, and in large doses emetic; it has been considerably used by the Eclectics in diarrhea, jaundice, scrofula, and related conditions. Externally the powdered bark is used as a stimulant to indolent ulcers, and the decoction as a gargle and injection in chronic inflammation of the throat.

For twenty years starting in 1916, bayberry root bark was listed in the American National Formulary. Use of bayberry in herbalism has declined since its peak in popularity in the 19th century.

2.3 Traditional Chinese and Asian Use

In folk medicine, bayberry was consumed as a tea for its tonic and stimulant properties and for treating diarrhea. Chinese traditional medicine texts record a history of bayberry use for more than 2,000 years. Research on the pharmacological activities of bayberry constituents began around 2000, with most early studies focusing on in vitro activities. The bark of Myrica rubra is a natural remedy widely used in China and other Asian countries to treat tissue and bone injuries, burns, scalds, gastrointestinal ulcers, and diarrhea.

Traditional Chinese medicine (TCM) applied bayberry to a range of oral, digestive, and infectious conditions. Bayberry is also reported to have been used as a charm medicine to exorcise spirits of the dead and to prevent diseases.

2.4 African Use

Myrica cordifolia, native to South Africa, has been traditionally used as an astringent, food source, and for tanning hides. Another species indigenous to Africa, Myrica quercifolia, has also been prescribed by native herbalists to cure stomachaches.

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3. Key Chemical Constituents and Established Mechanisms of Action

3.1 Overview of Phytochemistry

A number of compounds have been identified in bayberry. In the bark, tannins, triterpenes (myricadiol, taraxerol, and taraxerone), flavonoid glycosides, astringent resin, and gum have been described. The leaves and fruit contain anthocyanins (e.g., cyanidin-3-O-glucoside) and phenolic acids (ferulic, caffeic, sinapic, and salicylic). Spectroscopic and chromatographic methods for identification of myricetin, myricitrin, quercetin, and gallic acid have been described.

The kernel contains proteins, unsaturated fatty acids, tannins, magnesium, potassium, and calcium.

Myrica esculenta contains key phytochemicals such as diarylheptanoids, flavonoids, terpenoids, and glycosides, including myricetin, quercetin, myricitrin (myricetin 3-O-rhamnoside), kaempferol, isoquercetin, and rutin. Proanthocyanidins, quercetin 3-O-acetyl-rhamnoside, anthocyanin, isoquercitrin, quercetrin, prodelphinidins, myricitrin, and myricanol are the main phytochemicals likely responsible for biological activities across different extracts.

Chinese bayberry fruit is particularly rich in anthocyanins. Compared with other berries, bayberry fruit is a rich source of cyanidin-3-glucoside (C3G; e.g., 64.8 mg/100 g fresh weight in the 'Biqi' cultivar), which accounts for at least 85% of the anthocyanins in the fruit.

3.2 Myricitrin

Myricetin-3-O-α-rhamnoside (myricitrin) is a botanical flavone extracted from Chinese bayberries (Myrica rubra, Myrica cerifera, Myrica esculenta, etc.). Myricitrin exerts potent antioxidant activity with robust scavenging of free radicals compared to other flavonol rhamnosides and quercetin. Moreover, it inhibits protein kinase C and nitric oxide with considerable antinociceptive effects. It hinders the macrophages' production of tumor necrosis factor-alpha (a pro-inflammatory cytokine) and has documented anti-myeloperoxidase activity.

Myricitrin, a botanical flavonol glycoside, is abundant in the fruits, branches, bark, and leaves of Myrica cerifera and other plants. Myricitrin, isolated from Myrica cerifera, is a potent antioxidant. Research has hypothesized that myricitrin possesses protective effects against osteoporosis by partially reducing reactive oxygen species (ROS) and bone-resorbing cytokines in osteoblastic MC3T3-E1 cells and human bone marrow stromal cells.

3.3 Myricetin

Myricetin is a common plant-derived flavonoid well recognized for its nutraceutical value. It is one of the key ingredients of various foods and beverages, exhibiting a wide range of activities including strong antioxidant, anticancer, antidiabetic, and anti-inflammatory effects.

Myricetin (3,5,7-trihydroxy-2-(3,4,5-trihydroxyphenyl)-4-chromenone) is a natural flavonoid belonging to the sub-class flavonols. It was isolated primarily from Myrica nagi bark and occurs in free as well as glycosidic forms. It is commonly found in a wide range of medicinal plants, teas, berries, and wines. It is a popularly recognized compound in nutraceuticals, exhibiting pharmacological activities including antioxidant, anti-inflammatory, antidiabetic, antimicrobial, antiviral, antiplatelet, analgesic, and anticancer effects. It has also shown cardioprotective, cytoprotective, and neuroprotective properties.

3.4 Myricanol

Myricanol is an important ingredient in the bark of M. rubra. A review summarizing 26 years of published research on its pharmacological effects shows that myricanol has multiple bioactive properties, including antioxidant, anticancer, anti-inflammatory, antimicrobial, antidiabetic, and antihyperlipidemic effects.

Myricanol improves metabolic abnormalities in mice by activating the AMPK/SIRT1/PGC-1α signaling pathway. It also demonstrates significant anticancer, antioxidant, and anti-inflammatory actions, primarily by regulating Caspase and BCL-2 family proteins, inhibiting iNOS expression, scavenging free radicals, and interacting with Peroxiredoxin 5.

In the context of neuroscience research, an extract from Myrica cerifera (bayberry/southern wax myrtle) potently reduced both endogenous and over-expressed tau protein levels in cells and murine brain slices. The bayberry flavonoids myricetin and myricitrin were confirmed to contribute to this potency, but the diarylheptanoid myricanol was the most effective anti-tau component in the extract, with potency approaching the best targeted lead therapies.

Myricanol was also reported to exhibit anti-androgenic activity. Among the four constituents of Myricae cortex, myricanol showed the highest testosterone 5α-reductase inhibitory activity, with an IC50 of 3.7 mM.

3.5 Triterpenes

The plant contains several organic compounds, including triterpenes such as myricadiol, taraxerol, and taraxerone, as well as flavonoids, tannins, resins, gums, and phenols. Myricadiol has a slight impact on levels of potassium and sodium, while myricitrin has antibiotic properties.

The diarylheptanoids myricanone and myricanol are very active iNOS inhibitors; myricanone has been reported to be approximately 20 times more active than aminoguanidine (a standard positive control) in cell-based assays.

3.6 Anthocyanins and Phenolic Acids

The high antioxidant capacity of bayberry in vitro is attributed to its anthocyanins and a variety of phenolic acids, including caffeic, ferulic, sinapic, and salicylic acids. The predominant anthocyanin in Chinese bayberry fruit is cyanidin-3-O-glucoside (C3G). The biological activity of Chinese bayberry fruit and its bioactive components includes antidiarrheal effects, mediated through the composition and diversity of gut microbiota, inflammatory signaling pathways, and intestinal tight junction proteins.

3.7 Proanthocyanidins

Proanthocyanidins from Chinese bayberry leaves (BLPs) are promising as a potential antibacterial material against bacterial adhesion and biofilm formation. Studies found BLPs possessed antimicrobial activity with MIC and MBC values of 320 and 640 μg/mL, respectively, against Staphylococcus epidermidis. Scanning electron microscopy and flow cytometry analysis revealed a loss of cell structure and function after treatment with BLPs.

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4. Scientific Evidence by Area of Use

Bayberry has been evaluated for its anti-inflammatory, antioxidant, and cardiovascular effects, and has demonstrated activity in cancer and diabetes, with most data derived from animal or in vitro studies. Because clinical data are lacking, bayberry cannot be recommended for any indication.

4.1 Antioxidant Activity

Preclinical evidence (in vitro and animal models): In vitro and chemical studies of bayberry leaf, bark, and fruit have identified several chemical constituents with antioxidant capacity, including anthocyanin, phenolic, and flavonoid content, specifically myricetin and myricitrin. Protective effects against apoptosis and cell necrosis have been shown in endothelial, pancreatic, hepatic, colonic, and neuronal tissues.

Research efforts suggest bayberry extracts contain antioxidants that exhibit bioactivities counteracting inflammation, allergens, diabetes, cancer, bacterial infection, diarrhea, and other health issues.

Evidence strength: Predominantly in vitro. No controlled human clinical trials specifically evaluating antioxidant endpoints are available in the reviewed literature.

4.2 Anti-Inflammatory Activity

Preclinical evidence: Extracts from different plant parts exhibit diverse pharmacological activities such as antioxidant, anti-inflammatory, antimicrobial, antidiabetic, and antihyperlipidemic effects. At the molecular level, myricitrin inhibits the macrophage production of tumor necrosis factor-alpha and has anti-myeloperoxidase activity. Myricanol and myricanone both act as potent inhibitors of inducible nitric oxide synthase (iNOS), a key mediator of inflammatory responses.

Evidence strength: Entirely preclinical (cell-based and animal studies). No human anti-inflammatory trials specific to bayberry preparations have been identified in authoritative sources.

4.3 Antimicrobial and Antidiarrheal Activity

Preclinical evidence: Myricetin has demonstrated antimicrobial activity against E. coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi, Shigella flexneri, Staphylococcus aureus, Vibrio cholerae, and showed the best activity against P. aeruginosa (MIC 1.5 μg/mL).

The chemical myricitrin has anti-fever properties. Myricitrin, along with the tannins, has anti-diarrheal properties. Myricitrin works as an antibiotic, while the tannins have astringent properties.

Research on antibiotic-associated diarrhea (AAD) in a mouse model found that Chinese bayberry preparations and cyanidin-3-O-glucoside (C3G) modulated gut microbiota composition and reduced pro-inflammatory signaling via the NF-κB pathway. This study aimed to explore the therapeutic effect of Chinese bayberry on AAD for the first time. A BALB/c mouse model was established by intragastric administration of lincomycin (3 g/kg). Successfully modeled mice were treated with purified water, dried bayberry powder suspension (100 mg/kg), C3G suspension (40 mg/kg), or montmorillonite powder suspension (40 mg/kg). This was an animal study and does not constitute human clinical evidence.

Evidence strength: Preclinical only. Antibacterial findings are predominantly in vitro. Animal model data on diarrhea are suggestive but cannot be extrapolated to clinical practice without human trials.

4.4 Antidiabetic Activity

Preclinical evidence: Evidence shows that myricanol has multiple bioactive properties including antidiabetic and antihyperlipidemic effects. Myricanol improves metabolic abnormalities in mice by activating the AMPK/SIRT1/PGC-1α signaling pathway.

In animal research, a standardized bayberry juice extract markedly attenuated bodyweight gain and decreased glycolipid metabolism-related markers including insulin, leptin, glucagon, triglyceride (TG), total cholesterol (TC), LDL-cholesterol, and alanine aminotransferase (ALT) levels. Liver weight and hepatic lipid accumulation were also significantly reduced. Gene expressions of insulin 1 (INS1) and glycogen synthase kinase 3β (GSK3b) were markedly inhibited while hepatic phosphorylation of AMPKα was significantly increased, indicating that the extract may exert an antidiabetic effect through an AMPK-dependent pathway. White bayberry rich in proanthocyanidins and flavonols was concluded to have great potential in the regulation of diabetes mellitus.

The hypoglycemic effects of Chinese bayberry leaves proanthocyanidins (BLPs) have been demonstrated in in vitro models using human Caco-2 cells, where BLPs inhibited intestinal glucose transport.

Evidence strength: All data are preclinical (animal and in vitro). No controlled human clinical trials on antidiabetic effects of bayberry are available in the reviewed sources.

4.5 Hepatoprotective / Nonalcoholic Fatty Liver Disease (NAFLD)

Human clinical evidence (single identified trial): Guo et al. investigated the effect of bayberry on NAFLD markers in a randomized, placebo-controlled, double-blind, crossover trial with 88 NAFLD patients. Individuals with a BMI >23.1 kg/m² who met diagnostic criteria for NAFLD by ultrasonography were recruited to consume 250 mL of bayberry juice or placebo twice daily for 4 weeks each.

This is the single human clinical trial on bayberry identified in authoritative sources at the time of this writing. Because clinical data are lacking more broadly, bayberry cannot be recommended for any indication. There is insufficient reliable evidence to determine a standardized dosage for bayberry.

Evidence strength: One small randomized controlled trial, of limited duration (4 weeks), using juice form. Results are not independently reproducible from the information available and must be considered preliminary.

4.6 Anticancer Activity

Preclinical evidence: Some studies have shown that Chinese bayberry extracts have anti-cancer properties, with flavonoids (cyanidin-3-O-glucoside, myricanol, prodelphinidins, proanthocyanidins, and isoquercitrin) having been shown to inhibit apoptosis in a variety of tumor cells. The molecular underpinnings of these extracts' anti-tumor action have been subject to several investigations. For instance, cyanidin-3-O-glucoside found in Chinese bayberry fruit inhibits the development of stomach cancer xenografts in mice in a dose-dependent manner.

Various compounds from M. cerifera bark exerted activity against leukemia, lung, and breast cancer cells. Bayberry leaves proanthocyanidin's (BLP's) role in cell cycle arrest and anti-angiogenic activity in ovarian cancer cells has not yet been fully elucidated. Some studies have shown that Chinese bayberry extracts have anti-cancer properties, with many flavonoids having been shown to inhibit apoptosis in a variety of tumor cells.

Evidence strength: All anticancer evidence is in vitro and/or animal-based. No human clinical trials of bayberry for cancer prevention or treatment are documented in the reviewed literature.

4.7 Neurological / Tau-Related Research

Preclinical evidence: An extract from Myrica cerifera potently reduced both endogenous and over-expressed tau protein levels in cells and murine brain slices. The bayberry flavonoids myricetin and myricitrin were confirmed to contribute to this potency, but myricanol was most effective. Target-based drug discovery for Alzheimer's disease centered on modulation of the amyloid-β peptide has met with limited success, and recent efforts have focused on targeting the microtubule-associated protein tau. Tau pathologically accumulates in more than 15 neurodegenerative diseases and is most closely linked with post-symptomatic progression in Alzheimer's disease.

The most powerful anti-tau compound in bayberry was found to be the diarylheptanoid myricanol, rather than myricitrin or myricetin. (+)-αR,11S-myricanol, isolated from M. cerifera, decreased tau expression in HeLa-C3, IMR32 cells and mice brain slices dose-dependently, with an EC50 of 35 µM in HeLa-C3 cells.

Myricanol from M. rubra exerted protective effects on neural cells by increasing cell vitality and preserving cell morphology after exposure to the neurotoxin H₂O₂.

Evidence strength: In vitro and ex vivo (murine brain slices) only. This research is exploratory and has not advanced to human clinical studies.

4.8 Cardiovascular and Antihypertensive Activity

Preclinical evidence: Early studies suggest that Myrica may have beneficial effects, including anticancer, antioxidant, blood pressure-lowering, and antifungal activities. At the molecular level, myricitrin has been shown to inhibit vascular adhesion molecule expression in TNF-α-stimulated vascular smooth muscle cells, an action with potential implications for atherosclerosis. However, these findings are in vitro and their clinical relevance is undetermined.

Evidence strength: Preclinical only. No human cardiovascular trials of bayberry extracts are available.

4.9 Bone Health

Preclinical evidence: Oxidative stress is a crucial pathogenic factor in the development of osteoporosis. Myricitrin, isolated from Myrica cerifera, is a potent antioxidant. Research hypothesized that myricitrin possesses protective effects against osteoporosis by partially reducing reactive oxygen species (ROS) and bone-resorbing cytokines in osteoblastic MC3T3-E1 cells and human bone marrow stromal cells. Studies revealed that myricitrin significantly improved certain osteogenic markers in these cells.

Evidence strength: Cell-based (in vitro) only.

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5. Body Systems and Health Areas Associated with Bayberry

• Respiratory system: Bayberry has been used to support respiratory function, especially when bringing tone to excessively wet mucous membranes is called for.
• Digestive system: In folk medicine, bayberry was consumed as a tea for its tonic and stimulant properties, and for treating diarrhea. Astringent tannins and myricitrin have both been associated with anti-diarrheal action.
• Immune and infectious disease: Traditional use as an antimicrobial and antipyretic agent; in vitro antimicrobial activity demonstrated against multiple human pathogens.
• Hepatic (liver) system: Animal studies have shown that berries rich in anthocyanins and phenolic acids might be useful to improve NASH-related symptoms of oxidative stress, dyslipidemia, liver steatosis, and inflammation.
• Metabolic/endocrine system: Preclinical antidiabetic effects via AMPK pathway activation and α-glucosidase inhibition.
• Neurological system: Myricanol reduces tau protein accumulation in cell and animal models relevant to Alzheimer's disease research.
• Musculoskeletal system: Myricitrin's in vitro effects on osteogenic markers suggest potential relevance to bone health.
• Dermatological (topical use): Bayberry is sometimes used as a gargle for sore throat, as a douche for vaginal discharge, and as an ointment for skin ulcers and wounds.
• Oral health: The dried root bark is used medicinally and as a dyeing/tanning agent. Traditional topical use for bleeding gums and oral inflammation is well documented in the historical record.

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6. Dosage Forms and Reported Dosages

There is insufficient reliable evidence to determine a standardized dosage for bayberry. Because clinical data are largely lacking, bayberry cannot be recommended for any indication based on current evidence.

The following dosage information appears in the reviewed literature as used historically or in specific research contexts:

• Decoction (root bark): Prepared by boiling one teaspoonful of root bark in a cup of cold water. A decoction is prepared by adding a teaspoonful of root bark to a cup of cold water and boiling the mixture. The resultant solution is allowed to cool for approximately 10 to 15 minutes.
• Tincture (root bark): A tincture of bayberry root bark at a dosage of 1 mL to 3 mL three times daily has been described.
• Bayberry juice (clinical trial): Bayberry juice 250 mL twice daily for 4 weeks was used in one small clinical trial of patients with features of nonalcoholic fatty liver disease.
• Dried bayberry powder (animal model): Dried bayberry powder suspension at 100 mg/kg was used in an animal model of antibiotic-associated diarrhea. (Not a human dosage.)

Clinical trials do not provide dosage recommendations for bayberry.

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7. Safety Considerations and Notable Interactions

7.1 Carcinogenicity Concern

The elevated tannin concentration of bayberry bark is carcinogenic in rats, which precludes general internal use of the plant bark in humans. The action of tannins relating to cancer is unclear in humans, with studies indicating both pro- and anti-cancer effects. This carcinogenicity finding in rodent studies remains a significant unresolved safety signal for the root bark.

7.2 Mineralocorticoid Activity and Electrolyte Effects

Large doses may cause typical mineralocorticoid side effects such as sodium and water retention and hypertension. Caution: use of Myrica cerifera during pregnancy and lactation should be avoided due to possible mineralocorticoid and carcinogenic activity.

7.3 Reproductive Toxicity

The triterpene myricadiol has been shown to be spermatocidal, and antiandrogenic activity of the bark extract of M. rubra has also been reported.

7.4 Gastrointestinal Effects

Use cautiously in large doses, as secondary sources report that bayberry may cause nausea and gastrointestinal disturbances. Bayberry bark is generally considered safe when used in small amounts, though it can be toxic in large doses due to high tannin levels. Prolonged use or high doses may cause digestive upset or liver issues.

7.5 Allergic Reactions

In a human study, 15% of 400 subjects evaluated for allergic respiratory symptoms had a positive reaction to bayberry pollen extract skin tests. Scientific safety evidence is lacking, although the bark, leaves, and fruits of several species of Myrica have been traditionally used and consumed without reports of adverse effects. Bayberry is not listed in the United States Food and Drug Administration (FDA) Generally Recognized as Safe (GRAS) list.

Bayberry is listed as an allergenic in the U.S. FDA Vaccines, Blood & Biologics Database. Substances labeled as such are regulated by the Center for Biologics Evaluation and Research. A diagnosis of hay fever from southern wax-myrtle (Myrica cerifera) has been noted.

Plant allergy, including severe, whole-body allergic reaction, has been documented. Cross-sensitivity with other fruits has been reported.

7.6 Anticoagulant/Antiplatelet Potential

Reduction of blood clot formation has been described. This interaction is not well-characterized in formal pharmacokinetic or clinical studies, but individuals taking anticoagulant or antiplatelet medications should be aware of this potential interaction.

7.7 Pregnancy and Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking. Multiple sources caution against use during pregnancy due to the potential mineralocorticoid and carcinogenic activity of the root bark. Pregnant women should not use bayberry.

7.8 Regulatory Status

Bayberry is not listed in the United States Food and Drug Administration (FDA) Generally Recognized as Safe (GRAS) list. Bayberry root bark was listed in the American National Formulary for twenty years starting in 1916, but is no longer recognized in that context. No current European or U.S. pharmacopoeial monograph for bayberry was identified in the reviewed literature.

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8. Summary of Evidence Status

Clinical trials on bayberry bark are limited. Studies have explored its anti-inflammatory and antimicrobial effects, and its flavonoids have shown potential in lab-based antioxidant research. No large-scale clinical studies have definitively confirmed its efficacy for any specific health condition, so it remains primarily in the realm of traditional and complementary medicine.

The most robust scientific research to date involves the isolation and in vitro characterization of individual constituents — particularly myricetin, myricitrin, myricanol, cyanidin-3-O-glucoside, and proanthocyanidins — in cell-based and animal models. The sole identified randomized controlled trial in humans involved Chinese bayberry juice (250 mL twice daily for 4 weeks) in 88 NAFLD patients; broader clinical evidence is absent. Until well-powered, adequately controlled human trials are conducted, bayberry's therapeutic claims rest predominantly on traditional use and preclinical experimental data.

References

• Jones et al. (2011). The Diarylheptanoid (+)-aR,11S-Myricanol and Two Flavones from Bayberry (Myrica cerifera) Destabilize the Microtubule Associated Protein Tau. Journal of Natural Products. PMC3070757.
• Pharmacological Effects and Mechanisms of Action of Myricanol. Molecules (2025). MDPI.
• Pharmacognostical, Phytochemical and Pharmacological Aspects of Myrica rubra (Chinese Bayberry): An update. ScienceDirect (2024).
• A comprehensive review on taxonomy, traditional uses, phytochemistry, pharmacological activities and quality control of Myrica esculenta. ScienceDirect (2025).
• Biological Activities of Extracts from Chinese Bayberry (Myrica rubra): A Review. Plant Foods for Human Nutrition (2013). Springer.
• Protective effects of myricitrin against osteoporosis via reducing reactive oxygen species and bone-resorbing cytokines. Toxicology and Applied Pharmacology (2014). ScienceDirect.
• Myricetin: A Dietary Molecule with Diverse Biological Activities. PubMed (2016).
• Myricitrin: A promising herbal therapy for periodontitis in immunosuppressed status. PMC (2023).
• Myrica — an overview. ScienceDirect Topics.
• Evaluation of antimicrobial and antibiofilm properties of proanthocyanidins from Chinese bayberry leaves against Staphylococcus epidermidis. PMC (2020).
• Chinese bayberry leaves proanthocyanidins inhibit intestinal glucose transport in human Caco-2 cells. Frontiers in Pharmacology (2024).
• Cyanidin-3-O-glucoside extracted from Chinese bayberry alleviates antibiotic-associated diarrhea. PMC (2022).
• Valorization of Bayberry (Morella rubra) Leaf By-Products. PMC (2025).
• Myricetin bioactive effects: moving from preclinical evidence to potential clinical applications. BMC Complementary Medicine and Therapies (2020). Springer.
• Bayberry Uses, Benefits & Dosage — Drugs.com Natural Products (medically reviewed, updated 2025).
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