Herbal Monograph
Grindelia
Grindelia robusta Nutt.
Asteraceae (Compositae)
Premier Western antispasmodic for bronchial asthma, cough, and respiratory catarrh with Commission E approval
Overview
Plant Description
Grindelia robusta is a robust, bushy perennial herb or subshrub growing 30-100 cm (1-3 feet) tall from a branching taproot. The stems are erect, round, strongly branched in the upper portions, smooth or slightly hairy, and often reddish or purplish near the base. The leaves are alternate, sessile (clasping the stem), oblong to spatulate, 2-7 cm long, with serrate to dentate margins; they are thick, leathery, and often dotted with resinous glands that give them a sticky, varnished appearance. The basal leaves are larger and more spatulate, while the upper cauline leaves are progressively smaller and more lanceolate. The flower heads are terminal, solitary or in loose corymbs, typically 2-4 cm in diameter. The involucre is distinctive and diagnostically important: it consists of multiple overlapping rows of phyllaries (bracts) that are strongly resinous and glutinous, exuding a thick, white, milky resin that coats the unopened and opening flower heads in a conspicuous sticky mass -- this is the gum that gives the plant its common names. The ray florets are bright golden-yellow, 25-40 in number, 8-15 mm long; the disc florets are also yellow, tubular, and numerous. The achenes (fruits) are compressed, smooth, topped with 2-3 deciduous awns. The entire plant has a balsamic, resinous odor and a markedly bitter, aromatic taste. Flowering occurs from June through October, with peak bloom typically in August (hence 'August Flower').
Habitat
Grindelia robusta is native to open, disturbed, and semi-arid habitats of California and the Pacific coastal region. It thrives in alkaline or saline soils and is characteristically found in coastal salt marshes, alkaline flats, roadsides, waste ground, dry hillsides, and disturbed areas from sea level to approximately 600 m elevation. It is well adapted to drought and tolerates poor, rocky, or sandy soils. The plant is a selenium accumulator and may concentrate selenium from seleniferous soils -- a factor relevant to sourcing plant material for medicinal use. It often colonizes disturbed ground and can behave as a ruderal pioneer species.
Distribution
Native to western North America, primarily California, extending into Oregon, Nevada, and Baja California (Mexico). The genus Grindelia as a whole is broadly distributed across North, Central, and South America, with approximately 60 species. G. robusta is concentrated along the California coast and Central Valley. G. squarrosa has a much wider distribution across the Great Plains, Midwest, and Rocky Mountain states. Grindelia species have been introduced to parts of Europe (particularly Spain, France, Italy, and Germany), where G. robusta and G. squarrosa are occasionally cultivated for the European phytomedicine market, particularly to supply the German Commission E-approved indication.
Parts Used
Aerial parts (flowering tops and leaves)
Preferred: Dried flowering tops for infusion; fresh or dried herb tincture (1:5 in 60% ethanol); fluid extract
The primary medicinal part is the flowering tops (herba) collected during bloom. The flower heads -- particularly the resinous involucres with their thick, white, sticky exudate -- are the richest source of the therapeutically active diterpene resin (containing grindelic acid). The upper leaves also contribute flavonoids, tannins, and additional resinous material. The USP, BHP, and Commission E monographs all specify the aerial parts or flowering tops as the official drug. The resin content of the flower heads (10-20% by dry weight) is significantly higher than in the stems or lower leaves, making the flowering tops the preferred harvest material.
Leaves
Preferred: Fresh leaf poultice for topical use; dried leaf infusion
The leaves alone are sometimes used, particularly in Native American traditions, as a poultice for skin conditions (poison ivy/oak dermatitis, insect stings) and as a simpler preparation for mild respiratory complaints. Leaves contain flavonoids, tannins, and some resinous material but at lower concentrations than the flowering tops. The basal and mid-stem leaves are larger and more suitable for poultice preparation.
Key Constituents
Diterpene acids (labdane-type diterpenoids)
The diterpene acid fraction -- principally grindelic acid -- is considered the key pharmacologically distinctive constituent class of Grindelia and the primary basis for its antispasmodic and expectorant actions. Grindelic acid relaxes bronchial smooth muscle, likely through a direct spasmolytic mechanism on airway smooth muscle rather than via beta-adrenergic pathways. This action is central to the plant's historical and current use for asthmatic bronchospasm, spasmodic cough, and bronchitis. The diterpene acids are concentrated in the resinous exudate of the flower heads and require alcoholic extraction for optimal recovery. The resin also acts as a topical protectant and mild antimicrobial when applied externally.
Resins (oleoresin complex)
The high resin content is fundamental to Grindelia's therapeutic identity. The resin provides a dual action: (1) a physical demulcent/protective coating on irritated respiratory mucosae, soothing cough and irritation, and (2) a matrix for the pharmacologically active diterpene acids (grindelic acid) that deliver bronchial antispasmodic and expectorant effects. The resinous quality also makes Grindelia useful as a topical protectant for skin conditions. The Commission E monograph specifically references the resin and diterpene acid content as relevant to the approved indication.
Saponins
The saponin fraction contributes to the expectorant action of Grindelia by acting as a surfactant that reduces the viscosity and surface tension of bronchial mucus, promoting its clearance from the airways. This mechanism is complementary to the antispasmodic action of the diterpene acids. Saponin-mediated expectoration is a reflex mechanism stimulated by irritation of gastric mucosa, which triggers a vagal reflex increasing bronchial secretions (reflex expectorant action).
Flavonoids
The flavonoid fraction contributes anti-inflammatory, antioxidant, and antihistamine activity that complements the primary antispasmodic and expectorant effects of the diterpene resin. Quercetin's mast cell-stabilizing properties are particularly relevant to Grindelia's traditional use in allergic respiratory conditions. The flavonoids also provide vascular-protective and mild diuretic effects.
Tannins
Tannins provide mild astringent activity that helps tone boggy, over-secreting respiratory mucous membranes. This makes Grindelia a useful herb in conditions where there is both spasm and excessive, thin mucous production. The tannin-resin combination creates an effective topical application for weeping skin conditions, poison ivy/oak dermatitis, and minor wounds.
Volatile oil (essential oil)
The volatile oil fraction contributes aromatic and mildly antispasmodic properties. While present in relatively small quantities, the volatile constituents contribute to the overall sensory profile and may enhance the bronchodilatory and mucolytic effects of the herb through vapor action on the respiratory epithelium. The aromatic quality also classifies Grindelia as partially 'aromatic' in energetic terms.
Phenolic acids
Phenolic acids contribute antioxidant and mild anti-inflammatory effects that support the overall therapeutic action of the herb. They are water-soluble and are well represented in both infusion and tincture preparations.
Minerals and trace elements
The selenium accumulating property of Grindelia is primarily a safety consideration rather than a therapeutic advantage. While trace amounts of organic selenium contribute to antioxidant enzyme function, the variable and potentially high selenium content of wild-harvested Grindelia from seleniferous soils poses a toxicity risk. Reputable suppliers source from non-seleniferous soils or test plant material for selenium levels. This consideration is unique among commonly used Western medicinal herbs and should be communicated to practitioners and consumers.
Herbal Actions
Relieves smooth muscle spasm
The most clinically significant action of Grindelia. Grindelic acid and the diterpene resin fraction directly relax bronchial smooth muscle, producing a spasmolytic effect on the airways that is the pharmacological basis for the herb's historical use in asthmatic bronchospasm and spasmodic cough. This action is well recognized in the Eclectic medical literature, where Grindelia was one of the most valued antiasthmatic remedies. Felter and Lloyd (King's American Dispensatory, 1898) described Grindelia as 'one of the most important agents for the relief of asthmatic paroxysms.' The BHP (1983) lists the specific indication as bronchial asthma. The antispasmodic action extends to some degree to other smooth muscle, though the respiratory tract is the primary target.
[1, 3, 4, 6]Promotes the discharge of mucus from the respiratory tract
Grindelia acts as an expectorant through multiple complementary mechanisms: (1) the saponin fraction acts as a reflex expectorant, stimulating vagal-mediated increases in bronchial secretion through mild gastric irritation; (2) the resinous demulcent fraction soothes irritated respiratory mucosa and helps loosen adherent, viscid mucus; (3) the volatile oil fraction provides a mild direct stimulant effect on the respiratory epithelium. This combination of mechanisms makes Grindelia effective for both dry, spasmodic coughs (where the demulcent-antispasmodic action predominates) and productive coughs with thick, tenacious mucus (where the expectorant-mucolytic action is primary). The Commission E approved Grindelia specifically for catarrhs of the upper respiratory tract.
[1, 3, 4, 6]Reduces inflammation
Anti-inflammatory activity is contributed by multiple constituent classes: flavonoids (kaempferol, quercetin, luteolin) inhibit COX-2, LOX, and NF-kB signaling; diterpene acids modulate inflammatory mediator release; phenolic acids provide antioxidant-mediated anti-inflammatory effects. Quercetin additionally stabilizes mast cells and inhibits histamine release, relevant to the anti-allergic applications of Grindelia. The anti-inflammatory action supports the primary respiratory indications by reducing airway inflammation and edema in bronchitis and asthma.
[1, 3]Soothes and protects irritated mucous membranes
The high resin content (10-20%) acts as a topical protectant and demulcent on irritated mucous membranes, particularly of the respiratory tract. Unlike mucilaginous demulcents (e.g., marshmallow, slippery elm) which coat membranes with polysaccharide gels, Grindelia's demulcent action is resin-based -- the sticky oleoresin forms a protective film over irritated epithelium. This resinous demulcent quality is particularly effective for soothing the dry, irritated, raw feeling in the airways associated with persistent cough. Topically, the resin provides a similar protective coating on irritated skin.
[3, 4, 6]Kills or inhibits the growth of microorganisms
Grindelia demonstrates mild antimicrobial activity, primarily attributed to the diterpene acids (grindelic acid) and the resinous fraction. Activity has been demonstrated in vitro against certain gram-positive bacteria. The antimicrobial action is modest compared to strongly antimicrobial herbs (e.g., goldenseal, oregano) but may contribute to the overall therapeutic effect in respiratory infections where both antimicrobial and antispasmodic actions are needed. Topically, the resinous quality provides a mild antiseptic protective barrier.
[3, 6]Stimulates digestive secretions via bitter taste receptors
Grindelia has a distinctly bitter taste due to the diterpene acid and resin content. This bitterness stimulates digestive secretions through the bitter reflex pathway (activation of bitter taste receptors T2R on the tongue and GI tract, triggering vagal stimulation of gastric acid, bile, and pancreatic enzyme secretion). The bitter quality is secondary to the primary respiratory actions but contributes to the overall digestive-tonifying effect and to the reflex expectorant mechanism (gastric stimulation triggering vagal bronchial secretion).
[3, 6]Increases urine production and output
A mild diuretic action is noted in several traditional and Eclectic sources for Grindelia. Felter and Lloyd mention its use in cystitis and urinary tract conditions. The mechanism may involve flavonoid-mediated increase in renal blood flow and glomerular filtration. This action is mild and not a primary clinical indication, but it contributed to the Eclectic use of Grindelia in combination formulas for genitourinary conditions.
[4, 6]Therapeutic Indications
Respiratory System
Bronchial asthma (spasmodic, non-allergic and allergic types)
Grindelia is one of the best-established Western herbal medicines for bronchial asthma. It has a POSITIVE Commission E monograph for catarrhs of the upper respiratory tract, is listed in the BHP (1983) with specific indications for bronchial asthma, and was included in the USP/NF from the late 19th to early 20th century as an antiasthmatic. The Eclectic physicians considered it among the most valuable remedies for asthmatic paroxysms. Felter and Lloyd stated it provided 'marked relief in spasmodic asthma.' The antispasmodic action of grindelic acid on bronchial smooth muscle is the primary mechanism. Grindelia is most effective for the spasmodic component of asthma (bronchospasm) rather than the allergic-inflammatory component, though the quercetin content provides some antihistamine activity. Used alone or in combination with other respiratory herbs (lobelia, ephedra, elecampane).
[1, 3, 4, 6, 7]Acute and chronic bronchitis
Commission E-approved indication. Grindelia addresses bronchitis through combined antispasmodic, expectorant, and demulcent actions: it relaxes bronchospasm, promotes expectoration of thick mucus, and soothes inflamed bronchial mucosa. The BHP lists bronchitis as a specific indication. Particularly valuable for bronchitis characterized by thick, tenacious sputum that is difficult to expectorate, accompanied by spasmodic, paroxysmal cough. The anti-inflammatory flavonoids and mild antimicrobial diterpene acids provide additional support. The Eclectic physicians used Grindelia extensively for chronic bronchial catarrh.
[1, 3, 4, 6]Catarrhs of the upper respiratory tract
This is the specific approved indication in the German Commission E monograph. Upper respiratory catarrh encompasses conditions with inflammation and excessive mucus production in the nose, sinuses, pharynx, and larynx. Grindelia's expectorant and anti-inflammatory actions help to loosen and clear congested mucus while reducing mucosal inflammation. The combination of resinous demulcent, saponin expectorant, and antispasmodic actions makes it well suited to catarrhal conditions with both congestion and spasmodic cough.
[1, 3]Spasmodic cough (whooping cough, persistent dry cough)
The Eclectic physicians employed Grindelia for spasmodic and whooping cough (pertussis), taking advantage of its direct bronchial antispasmodic action. Felter and Lloyd described its use for 'paroxysmal cough of any variety' and specifically mentioned whooping cough. The resinous demulcent quality soothes the irritated laryngeal and bronchial mucosa that triggers the cough reflex, while the antispasmodic action reduces the intensity of coughing paroxysms. Modern herbal practice continues to use Grindelia for persistent, spasmodic, dry or semi-productive coughs.
[3, 4, 6]Emphysema and chronic obstructive pulmonary disease (COPD) (adjunctive, symptomatic relief)
The Eclectic physicians used Grindelia for the dyspnea and spasmodic cough associated with emphysema. The antispasmodic and expectorant actions can provide symptomatic relief of bronchospasm and mucus retention in COPD. Grindelia does not reverse structural lung damage but may improve quality of life by easing breathing difficulty and facilitating mucus clearance. Best used as part of a comprehensive respiratory support protocol.
[3, 6]Skin / Integumentary
Poison ivy/oak dermatitis (Toxicodendron contact dermatitis)
One of the most well-known traditional topical uses of Grindelia, particularly among Native American peoples and subsequently adopted by Eclectic physicians and Western herbalists. A strong decoction or diluted tincture of Grindelia is applied topically to poison ivy/oak rash. The resinous constituents form a protective film over the affected skin, while tannins provide astringent action that helps dry weeping vesicles. The anti-inflammatory flavonoids and mild antimicrobial activity of the diterpene acids further support healing. Millspaugh (1892) specifically noted this application. The Pomo people of California traditionally used Grindelia leaf poultices for this purpose.
[6, 7, 8]Minor burns, insect bites, and skin irritation
The resinous, protective quality of Grindelia preparations makes them useful as a topical application for minor burns, insect bites, stings, and general skin irritation. Native American peoples of California used Grindelia poultices for a wide range of skin conditions. The resin provides a natural bandage-like protective layer, the tannins astringe weeping or oozing skin, and the mild antimicrobial properties help prevent secondary infection.
[6, 8]Eczema and dermatitis (topical, as adjunct)
Traditional topical use for various dermatitis conditions. The combination of protective resin, astringent tannins, and anti-inflammatory flavonoids can help manage weeping, inflamed skin lesions. Grindelia wash or diluted tincture applied as a compress may reduce oozing, soothe irritation, and protect damaged skin. Not a primary treatment for chronic eczema but may provide symptomatic relief as part of a topical regimen.
[3, 6]Cardiovascular System
Functional tachycardia and cardiac asthma (historical Eclectic indication)
The Eclectic physicians used Grindelia for what they termed 'cardiac asthma' -- dyspnea of cardiac origin -- and for functional tachycardia. Felter and Lloyd noted that Grindelia 'slows the pulse and lowers arterial tension.' This application reflects the 19th-century Eclectic understanding of the connection between respiratory and cardiac function. In modern terms, Grindelia's bronchodilatory action may provide symptomatic relief of dyspnea in patients with mild cardiac-pulmonary compromise, and the mild sedative-antispasmodic effect may slow an elevated heart rate in anxious or stressed individuals. This is not a primary cardiovascular indication in modern practice.
[6, 7]Urinary System
Cystitis and urinary tract irritation (adjunctive)
An Eclectic-era indication. Felter and Lloyd mentioned Grindelia's use in cystitis, attributing benefit to its antispasmodic and mild diuretic actions. The antispasmodic action may help relieve bladder spasm associated with urinary tract infection, while the mild diuretic effect promotes urinary flushing. The resinous and balsamic qualities of Grindelia share some character with other urinary antiseptic resins (e.g., buchu, uva ursi). This is a minor, secondary indication, not a primary use in contemporary practice.
[4, 6]Digestive System
Digestive sluggishness and poor appetite (as a bitter tonic)
The pronounced bitter taste of Grindelia stimulates digestive secretions via the cephalic phase reflex, increasing gastric acid, bile, and pancreatic enzyme output. While not a primary digestive herb, this bitter action provides a secondary benefit when Grindelia is prescribed for respiratory conditions in patients who also present with poor appetite or sluggish digestion. The Eclectic physicians noted its bitter tonic properties.
[3, 6]Immune System
Allergic rhinitis and hay fever (adjunctive)
Grindelia has traditional use for hay fever and allergic respiratory conditions, attributed to the quercetin-mediated mast cell stabilization and antihistamine activity, combined with the antispasmodic and expectorant actions that address the respiratory symptoms of allergic rhinitis (sneezing, congestion, watery discharge, and associated cough). Hoffmann (2003) mentions Grindelia as useful in allergic conditions affecting the respiratory tract. The herb addresses symptoms but does not modify the underlying allergic tendency.
[3, 4]Energetics
Temperature
warm
Moisture
dry
Taste
Tissue States
cold/depression, damp/stagnation, wind/tension
In Western herbal energetics, Grindelia is classified as warm and dry, reflecting its resinous, aromatic, and bitter nature. The warming quality relates to its stimulating effect on respiratory secretion and its ability to move stagnant, cold conditions in the lungs. The drying quality reflects the astringent tannin content and the ability to reduce excessive, boggy secretions -- though paradoxically, the resinous demulcent quality can also soothe dry, irritated membranes, making Grindelia more nuanced than a simple drying herb. The primary tastes are bitter (from diterpene acids and resins), pungent (from volatile oil constituents), and aromatic (from the overall essential oil and resin profile). Grindelia is most specifically indicated for cold/depressed respiratory conditions (bronchospasm with poor expectoration, weak respiratory drive), damp/stagnant states (excessive, thick, tenacious mucus in the bronchi), and wind/tension patterns (spasmodic cough, asthmatic bronchoconstriction). It is less suitable for hot/excited or dry/atrophic respiratory states where the warming, drying qualities could aggravate symptoms -- though the resinous demulcent property provides some balancing effect. CAVEAT: Herbal energetics are interpretive frameworks within Western herbalism, not standardized across all practitioners.
Traditional Uses
Native American (California tribes: Costanoan/Ohlone, Pomo, Miwok, and others)
- Topical poultice of fresh leaves and flowering tops for poison ivy/poison oak rash (Toxicodendron dermatitis)
- Decoction or poultice applied to skin eruptions, sores, insect bites, and minor wounds
- Infusion of flowering tops taken internally for coughs, colds, and chest congestion
- Decoction used as a wash for skin infections and inflammation
- Flower heads chewed or decocted for relief of bronchial complaints and asthma
- External application for burns and scalds
"The Costanoan (Ohlone) people of the San Francisco Bay region used Grindelia as a topical remedy for poison oak rash and various skin conditions. The Pomo people of northern California applied crushed Grindelia leaves and flowers to skin eruptions and used the decoction internally for respiratory complaints. Multiple California tribes recognized the sticky resinous flower heads as effective medicine for lung conditions and skin problems. Moerman (1998) documents ethnobotanical use of Grindelia species by numerous Native American groups across western North America."
Native American (Great Plains tribes: Lakota, Cheyenne, Pawnee, and others)
- Grindelia squarrosa used for coughs, colds, and bronchial congestion
- Decoction taken for kidney and urinary complaints
- Topical application for saddle sores, skin irritation, and insect bites
- Steam inhalation of boiling Grindelia for respiratory congestion
- Treatment of colic and stomach complaints
"Great Plains tribes used the more widely distributed Grindelia squarrosa (curlycup gumweed) for many of the same indications as coastal California tribes used G. robusta. The Lakota used decoctions for respiratory and urinary complaints. The Cheyenne used it for coughs and as a skin remedy. The Pawnee are recorded as using Grindelia internally for various complaints. These parallel uses across geographically distant tribes underscore the consistent recognition of Grindelia's respiratory and topical medicinal value."
[8]
Eclectic American medicine (19th-early 20th century)
- Primary antiasthmatic remedy: relief of bronchial asthma paroxysms, considered 'one of the most important agents' for this condition
- Treatment of chronic bronchitis and bronchial catarrh with thick, tenacious sputum
- Spasmodic and whooping cough (pertussis)
- Cardiac asthma and dyspnea associated with heart failure
- Applied topically in tincture or fluid extract for poison ivy/oak dermatitis
- Cystitis and bladder irritation (internal)
- Old, non-healing ulcers and skin conditions (topical wash)
- Burns and scalds (topical, diluted fluid extract)
- Functional tachycardia and 'irritable heart'
"Felter and Lloyd in King's American Dispensatory (1898) provide the most extensive Eclectic account: 'Grindelia is one of the most important agents for the relief of asthmatic paroxysms. It gives marked relief in spasmodic asthma, in the dyspnoea of emphysema, and in the bronchial catarrh of old people. Locally, it has few equals in the treatment of poisoning by Rhus Toxicodendron.' They further noted: 'It controls and lessens the paroxysms of whooping cough, and relieves the breathing in chronic bronchitis with profuse secretion. It slows the pulse and lowers arterial tension.' The fluid extract (dose: 15-60 drops) was the preferred preparation. Grindelia was official in the United States Pharmacopeia from the 1882 revision."
German Commission E phytotherapy (contemporary evidence-based phytomedicine)
- Approved for catarrhs of the upper respiratory tract
- Used in European phytomedicine as an antispasmodic and expectorant for bronchitis and respiratory catarrh
- Included in combination respiratory preparations in German and European herbal commerce
"The German Commission E issued a POSITIVE monograph for Grindelia herba (Grindeliae herba), approving its use for 'catarrhs of the upper respiratory tract.' This is one of relatively few North American herbs to receive a positive Commission E evaluation, reflecting the strength of the pharmacological and clinical evidence for its respiratory antispasmodic and expectorant actions. The Commission E monograph identifies the drug as the dried aerial parts of Grindelia robusta and/or G. squarrosa and notes the resin and diterpene acid content as relevant active constituents."
British Herbal Pharmacopoeia (BHP 1983)
- Specific indications: bronchial asthma, whooping cough, bronchitis
- Actions listed: antispasmodic, expectorant, hypotensive
- Recommended preparations: liquid extract (1:1 in 60% ethanol), tincture (1:5 in 60% ethanol)
"The British Herbal Pharmacopoeia (1983) includes a monograph on Grindelia (listing G. camporum and G. squarrosa), with actions described as antispasmodic, expectorant, and hypotensive. Specific indications are bronchial asthma, whooping cough, and bronchitis. The BHP provides dosage guidelines for liquid extract and tincture and notes the therapeutic applicability of the resinous flowering tops."
[4]
Modern Research
Grindelic acid: isolation, characterization, and pharmacological activity
Multiple phytochemical investigations have isolated and characterized grindelic acid and related labdane diterpenoids from Grindelia species. Grindelic acid has been identified as the principal pharmacologically active diterpene in the resin fraction, with demonstrated smooth muscle relaxant (antispasmodic) activity.
Findings: Grindelic acid and related diterpene acids from Grindelia robusta and G. squarrosa have been shown to relax isolated smooth muscle preparations, including bronchial smooth muscle, supporting the traditional and pharmacopeial antispasmodic indication. The mechanism appears to involve direct smooth muscle relaxation rather than receptor-mediated bronchodilation. Additional in vitro studies have demonstrated mild antimicrobial activity of grindelic acid against selected gram-positive organisms. The diterpene acid profile has been used as a chemotaxonomic marker to differentiate Grindelia species.
Limitations: Predominantly in vitro studies using isolated tissue preparations or bacterial cultures. Limited translation to in vivo pharmacokinetic and pharmacodynamic studies. The specific molecular mechanism of smooth muscle relaxation by grindelic acid has not been fully elucidated (calcium channel modulation, phosphodiesterase inhibition, and direct musculotropic effects have been proposed). No modern clinical pharmacology studies with isolated grindelic acid have been conducted.
Flavonoid and phenolic composition of Grindelia species
Phytochemical studies have characterized the flavonoid and phenolic acid profiles of Grindelia robusta and related species, identifying kaempferol, quercetin, luteolin, and their glycosides as principal flavonoid constituents, alongside chlorogenic acid and other hydroxycinnamic acids.
Findings: HPLC and spectroscopic analyses have confirmed the presence of quercetin, kaempferol, and luteolin (and their glycoside conjugates) in Grindelia aerial parts. These flavonoids possess well-documented anti-inflammatory, antioxidant, and antihistamine activities in broader pharmacological literature. Quercetin's ability to stabilize mast cells and inhibit histamine release provides a pharmacological rationale for Grindelia's traditional use in allergic respiratory conditions. Total flavonoid content varies with species, growing conditions, and plant part.
Limitations: Phytochemical characterization studies. The flavonoid activities are well established from studies on isolated flavonoids from many plant sources, not specifically from Grindelia extracts in clinical settings. The contribution of flavonoids to the overall therapeutic effect of whole Grindelia preparations (relative to the dominant diterpene resin fraction) has not been quantified in clinical studies.
Commission E evaluation of Grindelia
The German Commission E evaluated the evidence for Grindelia herba and issued a positive monograph approving its use for catarrhs of the upper respiratory tract. This evaluation considered traditional use evidence, pharmacological data on the diterpene acid and resin fraction, and the available clinical and pharmacological literature.
Findings: The Commission E determined that the evidence supported the efficacy and safety of Grindelia aerial parts for upper respiratory catarrh. The monograph identifies the resin (including diterpene acids) as the therapeutically relevant constituent class and notes antispasmodic and expectorant actions. No significant safety concerns were identified at recommended doses. The positive evaluation represents the most authoritative regulatory endorsement of Grindelia's therapeutic efficacy for respiratory indications.
Limitations: The Commission E evaluation process did not always require modern RCT evidence; expert consensus, pharmacological data, and long-standing traditional use were considered alongside any available clinical studies. The monograph provides limited detail on the specific clinical evidence reviewed. Modern clinical trial evidence specifically for Grindelia is very limited.
Selenium accumulation in Grindelia species
Ecological and analytical studies have documented that Grindelia species are selenium accumulator plants, concentrating selenium from seleniferous soils to levels that may exceed safe dietary thresholds.
Findings: Grindelia species growing on seleniferous soils in the western United States can accumulate selenium to concentrations significantly above background levels. The selenium is incorporated into organic forms (selenomethionine, selenocysteine) within plant tissues. Selenium accumulation varies markedly with soil selenium content, making geographic source a critical quality control parameter. Plants grown on non-seleniferous soils contain only background trace levels of selenium. This finding has important implications for sourcing of commercial Grindelia herb.
Limitations: These are primarily analytical/ecological studies rather than clinical toxicology studies. The actual selenium content of commercially marketed Grindelia preparations has not been systematically surveyed in published literature. The clinical relevance depends entirely on the selenium content of the specific source material, which varies by orders of magnitude depending on soil chemistry.
Ethnobotanical documentation of Grindelia in Native American medicine
Comprehensive ethnobotanical surveys have documented the extensive use of Grindelia species by numerous Native American peoples across western and central North America, establishing a robust traditional use record that predates Euro-American adoption of the plant.
Findings: Moerman's Native American Ethnobotany database documents the use of Grindelia species by over 20 tribal groups for respiratory, dermatological, urinary, and general medicinal purposes. The consistency of respiratory and topical skin indications across geographically distant tribes (California coastal peoples, Great Plains groups, Pacific Northwest nations) strongly supports the pharmacological basis for these uses. The topical application for poison ivy/oak dermatitis is one of the most consistently documented uses across multiple tribal traditions.
Limitations: Ethnobotanical documentation relies on historical records, oral histories, and retrospective surveys. Specific dosing, preparation methods, and outcomes are variably documented. Cultural context of traditional use may not translate directly to modern clinical application. Species identification in historical records may be imprecise.
[8]
Antimicrobial activity of Grindelia extracts
In vitro screening studies have evaluated the antimicrobial activity of Grindelia extracts and isolated constituents against a range of microbial pathogens.
Findings: Ethanolic extracts of Grindelia aerial parts demonstrated mild to moderate antimicrobial activity against selected gram-positive bacteria, including Staphylococcus aureus and Streptococcus species. Activity was primarily associated with the resinous/diterpene acid fraction. Little or no activity was observed against gram-negative organisms or fungi at tested concentrations. The antimicrobial potency was modest compared to strongly antimicrobial botanical agents.
Limitations: In vitro activity only. MIC values suggest mild activity unlikely to be clinically significant as a standalone antimicrobial. No in vivo or clinical antimicrobial studies have been conducted with Grindelia. Activity may vary with extract preparation method, plant source, and harvest timing.
Preparations & Dosage
Tincture
Strength: Fresh herb: 1:2 in 60-70% ethanol. Dried herb: 1:5 in 60% ethanol (BHP specification).
Prepare from fresh or dried flowering tops. Fresh herb tincture: use freshly harvested, coarsely chopped flowering tops in a 1:2 ratio with 60-70% ethanol. Dried herb tincture: use dried, coarsely ground flowering tops in a 1:5 ratio with 60% ethanol. Macerate for 2-4 weeks with daily agitation. The high alcohol percentage (60%+) is essential for dissolving the resinous diterpene acids -- lower alcohol percentages will leave much of the therapeutically active resin unextracted. Press, filter, and bottle. The resulting tincture should be deeply colored (amber to dark greenish-brown) and have a markedly bitter, resinous taste.
1-4 mL (20-80 drops) three times daily. BHP recommendation: 1-2 mL of 1:5 tincture in 60% ethanol, three times daily. For acute bronchospasm or asthmatic paroxysm: 2-4 mL every 2-3 hours as needed, reducing to three times daily as symptoms improve.
Three times daily for chronic conditions. Every 2-4 hours for acute respiratory spasm. Reduce frequency as symptoms improve.
Acute use: days to 2 weeks for acute bronchitis or asthma exacerbation. Chronic use: may be taken for several weeks to months for chronic bronchitis or recurrent asthma, with periodic reassessment.
Not generally recommended for children under 12 due to limited pediatric safety data and high alcohol content. For adolescents (12-16): half adult dose under qualified practitioner supervision.
The tincture is the preferred preparation for Grindelia in modern Western herbal practice because the high alcohol content efficiently extracts the resinous diterpene acids (particularly grindelic acid) that are the primary active constituents. Water alone is a poor solvent for these lipophilic resins. The BHP (1983) specifically recommends 60% ethanol for both liquid extract and tincture preparations. Fresh herb tinctures may contain a broader volatile constituent profile. The tincture has a strong, bitter, resinous taste and is usually taken in water. It may also be added to compound respiratory formulas alongside lobelia, elecampane, thyme, or licorice tinctures.
Infusion (Tea)
Strength: 2-4 g dried herb per 250 mL water (approximately 1:60 to 1:120)
Pour 250 mL (1 cup) of freshly boiled water over 1-2 teaspoons (2-4 g) of dried Grindelia flowering tops. Cover and steep for 10-15 minutes. Strain and drink. The infusion will be yellowish-green with a distinctly bitter, somewhat resinous taste. Covering the cup during steeping is important to retain volatile aromatic constituents.
1 cup (250 mL) three times daily. Commission E recommended dosage: 4-6 g of dried herb daily, taken as an infusion in divided doses.
Three times daily between meals
Acute use: 1-2 weeks. May be continued longer for chronic respiratory conditions with periodic reassessment.
Not well established. For older children (8-12): half adult dose. Not recommended for young children.
The infusion is a simpler but less complete extraction than the tincture. Hot water extracts the saponins, flavonoids, tannins, phenolic acids, and some of the more polar resinous compounds, but does NOT efficiently extract the lipophilic diterpene acids (grindelic acid) that are the primary antispasmodic constituents. Therefore, the infusion is better suited for mild respiratory catarrh and as a supplementary preparation to tincture therapy, rather than as the sole treatment for significant bronchospasm. The Commission E dosage is based on the infusion form. For topical use (e.g., poison ivy wash), a stronger infusion or decoction is prepared.
Decoction
Strength: Internal: 4-6 g per 500 mL. Topical (strong): 10-15 g per 500 mL.
Add 4-6 g of dried Grindelia flowering tops to 500 mL of cold water. Bring to a boil and simmer gently for 10-15 minutes. Strain. For topical use (poison ivy/oak wash, skin conditions), a stronger decoction may be prepared using 10-15 g per 500 mL, simmered for 15-20 minutes.
250 mL (1 cup) of standard decoction, two to three times daily for internal use. For topical application: apply the cooled, strong decoction directly to affected skin with a cloth compress or cotton pad, several times daily as needed.
Two to three times daily (internal). Multiple times daily (topical, as needed).
Internal: 1-2 weeks for acute conditions. Topical: until skin condition resolves.
Topical use: suitable for children as a skin wash. Internal use: half adult dose for children over 8 years, under practitioner guidance.
The decoction extracts slightly more of the resinous material than a simple infusion due to the prolonged heat, but still does not fully extract the lipophilic diterpene acids. For internal respiratory use, the tincture or fluid extract is generally preferred. The decoction is most commonly used for topical applications: as a wash for poison ivy/oak rash, eczema, burns, insect bites, and other skin conditions. The Eclectic physicians frequently used the fluid extract diluted in water for topical application rather than a decoction. A strong decoction also serves as a gargle for pharyngitis and laryngitis.
Capsule / Powder
Strength: 500 mg powdered herb per capsule. DER approximately 4:1 to 6:1 for concentrated extract capsules if available.
Dried Grindelia flowering tops, finely powdered (ground to pass through a 40-60 mesh sieve), filled into vegetarian or gelatin capsules. Standardized dry extracts (if available) may also be encapsulated.
500-1000 mg of powdered herb, three times daily. Total daily dose: 1.5-3 g of powdered herb (equivalent to 4-6 g of crude herb per Commission E guideline, accounting for capsule vs infusion bioavailability differences).
Three times daily with water, preferably taken with meals to reduce potential GI irritation from the resin.
May be used for several weeks for chronic respiratory conditions. Periodic reassessment recommended.
Not recommended for children under 12.
Capsules provide a convenient, taste-masked alternative to the intensely bitter tincture or infusion. However, the powdered whole herb in capsules may have reduced bioavailability compared to the tincture because the resinous constituents are not pre-dissolved in an appropriate solvent. The resin must be dissolved by gastrointestinal fluids for absorption. Taking capsules with a warm drink may improve dissolution. Capsules are most appropriate for mild, chronic conditions or for patients who cannot tolerate the taste of tincture or infusion. For acute bronchospasm, the tincture is preferred due to faster onset of action.
Poultice
Strength: Fresh herb applied directly, or dried herb moistened to form a paste.
For a fresh herb poultice: crush or bruise fresh Grindelia leaves and flowering tops and apply directly to the affected skin area, securing with a bandage or cloth. For a dried herb poultice: moisten dried Grindelia flowering tops with a small amount of hot water to form a paste, and apply to the skin. Cover with a clean cloth and leave in place for 20-30 minutes. Repeat as needed.
Apply to affected area as needed, 2-4 times daily.
Two to four times daily, or as needed for symptom relief.
Until the skin condition improves. Typically 3-7 days for poison ivy/oak, longer for chronic skin conditions.
Suitable for external use in children. Supervise to prevent ingestion.
The poultice is the traditional Native American method of applying Grindelia topically for poison ivy/oak rash, insect bites, burns, and skin irritation. The fresh herb is preferred because the intact resin provides maximum protective and soothing coverage of the skin. The sticky resinous exudate of the flower heads is especially valued for this purpose. In modern practice, a diluted tincture (1 part tincture to 3-4 parts water) applied with a cotton pad or cloth compress is often substituted for the fresh herb poultice and may be more convenient.
Syrup
Strength: Approximately 30-50 g dried herb per 500 mL finished syrup
Prepare a strong decoction: simmer 30-50 g dried Grindelia flowering tops in 500 mL water for 20-30 minutes. Strain thoroughly. Return the liquid to heat and reduce to approximately 250 mL. Add 250 mL of raw honey (or 200 g sugar for a simple syrup) and stir until dissolved. Optionally add 10-15 mL of Grindelia tincture to the cooled syrup to boost the diterpene acid content. Bottle and refrigerate.
1-2 teaspoons (5-10 mL) every 3-4 hours for acute cough, or three times daily for chronic conditions.
Three to six times daily during acute cough episodes. Three times daily for chronic maintenance.
Consume within 4-6 weeks if refrigerated. 2-3 months with added alcohol preservative.
For children over 2 years: 1/2 to 1 teaspoon three times daily. Not for infants under 1 year (honey-based preparations).
The syrup is a palatable preparation that partially masks Grindelia's intense bitterness, making it more acceptable for patients who find the tincture unpleasant. The honey provides additional demulcent, soothing properties for the throat and respiratory mucosa. This preparation is particularly appropriate for cough and bronchitis. Adding a small amount of tincture to the finished syrup compensates for the limited resin extraction achieved by water alone. Grindelia syrup combines well with other respiratory herbs -- thyme, elecampane, wild cherry bark, or licorice syrups can be blended for comprehensive respiratory support.
Safety & Interactions
Class 1
Can be safely consumed when used appropriately (AHPA Botanical Safety Handbook)
Contraindications
Individuals with confirmed allergy to plants in the Asteraceae family (including ragweed, chrysanthemums, chamomile, echinacea, arnica, yarrow, and related species) may potentially cross-react with Grindelia. Sesquiterpene lactone sensitivity is the most common allergenic mechanism in Asteraceae allergy. While Grindelia is not a common allergenic species, the theoretical risk of cross-reactivity warrants avoidance in individuals with documented Asteraceae allergy, particularly contact dermatitis from Compositae plants.
The high resin content (10-20%) of Grindelia preparations may cause gastrointestinal irritation in individuals who are sensitive to resinous plant preparations. In such individuals, nausea, gastric discomfort, or loose stools may occur. This is a relative contraindication: the preparation may be tolerated at lower doses or in dilute form, or the individual may need to use a different herb.
Drug Interactions
| Drug / Class | Severity | Mechanism |
|---|---|---|
| Theophylline, aminophylline, and other methylxanthine bronchodilators (Bronchodilators (methylxanthines)) | theoretical | Grindelia's bronchial antispasmodic action could theoretically produce additive bronchodilation when combined with pharmaceutical bronchodilators. This is more likely a beneficial additive effect than a harmful interaction, but awareness is warranted. |
| Beta-2 agonist bronchodilators (salbutamol/albuterol, formoterol, salmeterol) (Bronchodilators (beta-2 agonists)) | theoretical | Potential additive bronchodilation through different mechanisms (Grindelia: direct smooth muscle relaxation via diterpene acids; beta-2 agonists: beta-adrenergic receptor-mediated relaxation). The different mechanisms make a harmful synergistic interaction unlikely. |
| Sedative medications (benzodiazepines, barbiturates, Z-drugs) (CNS depressants / sedatives) | theoretical | Felter and Lloyd noted a mild sedative quality to Grindelia at higher doses. This could theoretically produce mild additive sedation with CNS depressant medications, though this interaction is speculative given the mild nature of Grindelia's sedative effect. |
Pregnancy & Lactation
Pregnancy
insufficient data
Lactation
insufficient data
There is insufficient clinical safety data on the use of Grindelia during pregnancy and lactation. No controlled studies in pregnant or breastfeeding women have been conducted. The Eclectic and traditional literature does not specifically address pregnancy use. The resinous and bitter nature of the herb, combined with its mild stimulant qualities, suggests conservative avoidance of therapeutic doses during pregnancy as a precautionary measure. The BHP and Commission E monographs do not address pregnancy use. As a general precaution, therapeutic doses should be avoided during pregnancy and breastfeeding unless specifically recommended by a qualified practitioner. Brief topical use (e.g., for poison ivy) during pregnancy is likely low-risk.
Adverse Effects
References
Monograph Sources
- [1] German Commission E (Bundesinstitut fur Arzneimittel und Medizinprodukte). Grindeliae herba (Grindelia). In: Blumenthal M, Busse WR, Goldberg A, et al., eds. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Austin, TX: American Botanical Council (1998) . ISBN: 978-0965555500
- [2] Blumenthal M, Busse WR, Goldberg A, Gruenwald J, Hall T, Riggins CW, Rister RS (eds.). The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. American Botanical Council, Austin, TX / Integrative Medicine Communications, Boston (1998) . ISBN: 978-0965555500
- [3] Hoffmann D. Medical Herbalism: The Science and Practice of Herbal Medicine. Healing Arts Press, Rochester, VT (2003) . ISBN: 978-0892817498
- [4] British Herbal Medicine Association Scientific Committee. British Herbal Pharmacopoeia: Grindelia. British Herbal Medicine Association, Bournemouth, UK (1983) . ISBN: 978-0903032070
Clinical Studies
- [5] Timmermann BN, Hoffmann JJ, Jolad SD, Schram KH, Cole JR, Tempesta MS. Grindelic acid and related diterpenes from Grindelia species. Journal of Natural Products (Lloydia) (1979) ; 42 : 419-423
Traditional Texts
- [6] Felter HW, Lloyd JU. King's American Dispensatory, 18th Edition: Grindelia. Ohio Valley Company, Cincinnati, OH (1898)
- [7] Millspaugh CF. American Medicinal Plants: Grindelia robusta and G. squarrosa. Boericke & Tafel, Philadelphia (1892)
- [8] Moerman DE. Native American Ethnobotany. Timber Press, Portland, OR (1998) . ISBN: 978-0881924534
Pharmacopeias & Reviews
- [9] United States Pharmacopeial Convention. The Pharmacopeia of the United States of America, Sixth Decennial Revision (USP VI): Grindelia. United States Pharmacopeial Convention, Washington, DC (1882)
- [10] American Pharmaceutical Association. The National Formulary, Fourth Edition (NF IV): Fluidextractum Grindeliae. American Pharmaceutical Association, Washington, DC (1916)
Last updated: 2026-03-02 | Status: review
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