Boldo

Metadata

• Common Names: Boldo (English/Spanish); Boldostrauch, Boldoblätter (German); Boldu
• Botanical Name: Peumus boldus Molina
• Plant Family: Monimiaceae
• Part Used: Leaves (Boldi folium)
• Evidence Quality Rating: Very Preliminary (Commission E approval only; no ESCOP or EMA monograph; minimal clinical data)

Approved Indications

Commission E

• Dyspeptic complaints
• Mild spasmodic complaints of the gastrointestinal tract

ESCOP

• No ESCOP monograph has been published for boldo

EMA/HMPC

• No EMA/HMPC monograph has been issued for boldo
• Boldo has not been assessed by the HMPC Committee on Herbal Medicinal Products

Agreement/Disagreement Between Bodies

• Only Commission E has approved boldo for therapeutic use
• The absence of ESCOP and EMA monographs reflects the limited clinical evidence base
• Commission E approval dates from the 1990s and was based primarily on pharmacological data and traditional use documentation
• The lack of subsequent European regulatory recognition suggests the evidence has not progressed sufficiently to meet modern assessment standards

Conditions Treated

Primary

• Dyspeptic complaints (functional dyspepsia)
• Mild spasmodic gastrointestinal complaints

Secondary

• Bile flow stimulation (choleretic)
• Mild hepatobiliary complaints
• Gallbladder dysfunction

Traditional/Historical

• In South American (particularly Chilean) traditional medicine, boldo has been used for liver and gallbladder complaints, digestive disorders, rheumatism, and urinary tract infections
• In European phytotherapy, boldo is used primarily as a choleretic and digestive tonic
• Traditional use as a mild sedative and anti-inflammatory in Latin American folk medicine

Mechanism of Action

• Isoquinoline alkaloids (total alkaloid content approximately 0.2-0.5%):
  • Boldine (approx. 0.1% of dried leaf): The principal pharmacologically active alkaloid; demonstrates choleretic activity (stimulation of bile secretion), antioxidant effects (scavenges hydroxyl and peroxyl radicals), anti-inflammatory activity, and hepatoprotective properties in animal models
  • Isoboldine: Structurally related aporphine alkaloid with similar but weaker pharmacological activity
  • Other minor alkaloids: reticuline, laurotetanine, N-methyllaurotetanine
• Essential oil (1-3% of dried leaf):
  • Ascaridole (16-40% of essential oil): A cyclic peroxide monoterpene; toxic at higher doses, causing GI irritation, hepatotoxicity, and CNS depression. The essential oil must not be used internally
  • 1,8-Cineole (eucalyptol): Contributes to spasmolytic and anti-inflammatory effects
  • p-Cymene: Monoterpene hydrocarbon with mild antiseptic properties
  • Linalool, alpha-terpineol: Contributing aromatic compounds
• Flavonoids: Including catechin, isorhamnetin glycosides; contribute to antioxidant and anti-inflammatory activity
• Choleretic mechanism: Boldine stimulates bile secretion by hepatocytes, increasing bile flow and improving fat digestion; this is the primary pharmacological rationale for the dyspepsia indication
• Spasmolytic activity: In vitro and animal studies suggest that the alkaloid fraction and essential oil components exert a relaxant effect on smooth muscle of the GI tract, contributing to the antispasmodic indication
• Antioxidant activity: Boldine is a potent free radical scavenger, with demonstrated cytoprotective effects on hepatocytes in experimental models

Clinical Evidence Summary

• No modern, high-quality RCTs have been identified for boldo monotherapy in dyspepsia or GI complaints
• Pharmacological studies: Boldine has been studied in vitro and in animal models, demonstrating choleretic, antioxidant, anti-inflammatory, and cytoprotective effects. These studies support the pharmacological plausibility of the traditional indications
• Combination products: Boldo is sometimes used in combination with other choleretic herbs (artichoke, milk thistle), but controlled clinical trials of these combinations are also lacking
• Traditional use documentation: Extensive documentation of boldo use in Chilean and broader South American traditional medicine, as well as in European phytotherapy since the late 19th century
• Commission E assessment: Based primarily on pharmacological plausibility and longstanding traditional use rather than clinical trial data
• The evidence base for boldo remains at the pharmacological and traditional use level; no clinical efficacy data meets modern standards of evidence-based medicine

European vs US/Anglophone Consensus

• Boldo is primarily known in continental European phytotherapy (especially Germany, France, and Southern Europe) and in South American herbal medicine
• In Germany, boldo leaf preparations are available as registered traditional herbal medicines for dyspeptic complaints
• Commission E approval provides a regulatory basis for use in Germany, though the herb is far less commonly used than artichoke or milk thistle for similar indications
• In the US and UK, boldo is not well known; it is available as a dietary supplement but has no FDA-evaluated therapeutic claims
• The concept of using choleretic herbs for dyspepsia remains predominantly a European clinical tradition
• US gastroenterology does not recognize boldo or choleretic therapy as part of standard clinical practice
• In South America, particularly Chile, boldo tea is a widely consumed folk remedy for digestive complaints

Safety Profile

Contraindications

• Bile duct obstruction: Choleretic stimulation is contraindicated in biliary obstruction
• Gallstones: May stimulate gallstone movement; use with caution or avoid
• Severe liver disease: Contraindicated in severe hepatic impairment
• Known allergy to boldo or other Monimiaceae plants
• The isolated essential oil must never be used internally due to ascaridole toxicity

Drug Interactions

• Anticoagulants and antiplatelet agents (warfarin, aspirin, clopidogrel): Boldine has demonstrated antiplatelet aggregation effects in experimental studies; concurrent use may increase bleeding risk. This is a clinically relevant interaction
• Hepatically metabolized drugs: Theoretical concern that boldine may affect hepatic drug metabolism, though specific CYP enzyme interactions have not been well characterized
• Antihypertensive medications: Some evidence of mild hypotensive effects from boldine; potential additive effect

Side Effects

• At recommended doses of the leaf preparation (not essential oil): generally well tolerated
• Nausea, mild GI discomfort (uncommon)
• Allergic reactions (rare)
• Ascaridole toxicity (from essential oil or overdose of leaf preparations): nausea, vomiting, diarrhea, CNS depression, hepatotoxicity, and in severe cases convulsions. Cases of fatal poisoning have been reported from ingestion of boldo essential oil
• Prolonged or excessive use should be avoided

Pregnancy/Lactation

• Contraindicated in pregnancy due to the presence of potentially toxic alkaloids and ascaridole
• Insufficient data on lactation safety; avoid use
• Not recommended for children under 12 years (insufficient data)

Clinical Dosage

Forms and Ranges

• Dried leaf (tea): 1-2 g of dried leaf per 150 mL boiling water, steeped 10-15 minutes; 2-3 times daily before meals
• Tincture (1:5 in 60% ethanol): 0.5-2 mL, 2-3 times daily
• Dry extract (DER 5-10:1): 200-400 mg, 2-3 times daily
• Daily dose of dried drug: 3-5 g (Commission E)
• Timing: Before meals to maximize choleretic effect
• Duration: Short-term use recommended; avoid continuous use exceeding 4 weeks
• Essential oil: Internal use is contraindicated; external use only under professional supervision

Key Standardized Products

• Boldo leaf preparations (Boldi folium) per Commission E standards
• Boldo is commonly found in European combination digestive products alongside artichoke leaf and milk thistle
• In South America, boldo leaf tea (prepared from dried leaves) is the traditional preparation

Sources

• Commission E Monograph: Boldi folium (Boldoblätter)
• Speisky H, Cassels BK. Boldo and boldine: an emerging case of natural drug development. Pharmacol Res. 1994;29(1):1-12
• O’Brien P, Carrasco-Pozo C, Speisky H. Boldine and its antioxidant or health-promoting properties. Chem Biol Interact. 2006;159(1):1-17
• Ruiz AL, et al. Pharmacology and toxicology of Peumus boldus and boldine. Braz J Pharm Sci. 2008;44(1):1-12
• Vogel H, et al. Boldo (Peumus boldus) — its botany, chemistry and pharmacology. Phytochem Rev. 2005;4:115-128
• Arzneipflanzenlexikon: Boldo (arzneipflanzenlexikon.info)

Connections

• Related to Artichoke and Milk Thistle as hepatobiliary and choleretic agents in European phytotherapy
• Compare with Gentian and Wormwood as bitter digestive tonics, though boldo acts primarily through choleretic rather than bitter-reflex mechanisms
• The ascaridole toxicity concern distinguishes boldo from most other digestive herbs and requires careful attention to dose and preparation form
• Boldo is one of the few South American herbs that has gained recognition in the European regulatory framework (Commission E)
• The dandelion root shares the choleretic indication and offers a comparison in terms of evidence level and safety profile