Herbal Monograph
Spearmint
Mentha spicata L.
Lamiaceae (Labiatae)
Anti-androgenic mint for PCOS, digestive comfort, and cognitive support
Overview
Plant Description
Spearmint is a vigorous, aromatic herbaceous perennial in the Lamiaceae (mint) family, growing 30-100 cm (12-40 inches) tall. The plant spreads aggressively via stolons (horizontal underground runners), forming dense colonies. Stems are square in cross-section (a characteristic feature of the Lamiaceae), erect to ascending, branching, and typically glabrous (hairless) or nearly so, in contrast to the hairy stems of some other Mentha species. Leaves are opposite, sessile or nearly so (lacking significant petioles, unlike peppermint which has distinct petioles), lanceolate to ovate-lanceolate, 5-9 cm long and 1.5-3 cm wide, with sharply serrated margins and an acute apex. The leaf surface is bright green, often with a slightly wrinkled or rugose texture, and punctate with abundant oil glands visible as translucent dots when held to light. The characteristic sweet, warm, slightly herbaceous aroma -- distinctly different from peppermint's sharp menthol coolness -- is released when leaves are bruised. Inflorescences are terminal, slender, interrupted verticillasters (whorled clusters) forming tapering spikes 4-10 cm long, giving the species its name ('spicata' means 'spiked'). Flowers are small (2-3 mm), lilac, pink, or white, with a two-lipped corolla. The calyx is five-toothed and glandular. Stamens are four, exserted beyond the corolla. The fruit consists of four small, smooth nutlets. Spearmint is largely sterile and propagates primarily vegetatively.
Habitat
Spearmint is found in moist to wet habitats including stream banks, ditches, wet meadows, lakeshores, and disturbed moist ground. It thrives in full sun to partial shade and prefers rich, loamy, well-drained to moderately wet soils with a pH of 6.0-7.5. It tolerates a range of soil types but performs best in fertile, humus-rich conditions with consistent moisture. In cultivation, it grows readily in garden beds, containers, and herb gardens, though its aggressive stoloniferous habit requires containment measures (sunken barriers, containers) to prevent it from overtaking other plantings. It is hardy in USDA zones 3-11 and tolerates light frost, though top growth dies back in winter in colder climates.
Distribution
Mentha spicata is believed to be native to Europe and southwestern Asia (the Mediterranean region, including Turkey, the Balkans, and the Near East), though its exact native range is obscured by millennia of human cultivation and naturalization. It is now cosmopolitan, naturalized on every continent except Antarctica. Major regions of cultivation include: the Mediterranean (Turkey, Greece, Italy, Spain, Morocco, Egypt), where it is integral to culinary and tea culture; the United States (principally Indiana, Michigan, and the Pacific Northwest for essential oil production); India (Uttar Pradesh, Punjab); China; and temperate regions of South America, Australia, and southern Africa. The United States is one of the world's largest producers of spearmint essential oil, with approximately 2,500-3,000 tonnes produced annually, primarily from irrigated fields in the Columbia Basin of Washington and Oregon.
Parts Used
Aerial parts (leaves and flowering tops)
Preferred: Dried leaf for infusion (tea); fresh leaf for culinary use; hydroalcoholic tincture of dried or fresh herb
The primary medicinal and culinary part. Fresh or dried leaves and tender stems are used for herbal tea (tisane), tinctures, and culinary preparations. The leaf is the pharmacopeial drug listed in the European Pharmacopoeia (Menthae crispae folium) and other references. The essential oil-rich glandular trichomes on the leaf surface contain the highest concentration of volatile aromatic compounds, particularly carvone, limonene, and 1,8-cineole. The non-volatile polyphenolic compounds (rosmarinic acid, luteolin, caffeic acid derivatives) are abundant in the leaf tissue itself.
Essential oil (Menthae spicatae aetheroleum)
Preferred: Steam-distilled essential oil for external/aromatherapy use; diluted in carrier oil for topical application
Steam-distilled essential oil from the fresh or partially dried aerial parts. The essential oil is dominated by carvone (50-70%), with limonene (10-25%), 1,8-cineole (1-5%), and minor amounts of dihydrocarvone, carveol, and myrcene. Used externally in aromatherapy, topical preparations, and flavoring. The essential oil is NOT equivalent to the whole herb for internal therapeutic use -- it is highly concentrated and must be used with appropriate dilution. Internal use of undiluted essential oil is not recommended without professional guidance.
Key Constituents
Monoterpenoids (essential oil components)
The monoterpenoid-rich essential oil, dominated by carvone, is responsible for spearmint's carminative, antispasmodic, and antimicrobial actions. Carvone relaxes gastrointestinal smooth muscle via calcium channel modulation, providing the pharmacological basis for spearmint's traditional digestive use. The essential oil profile is what most clearly differentiates spearmint from peppermint -- spearmint lacks the menthol and menthone that define peppermint's pharmacology. This means spearmint does not produce the intense cooling sensation or the potent antispasmodic effect of peppermint on the lower esophageal sphincter, making spearmint generally safer in gastroesophageal reflux disease (GERD) where peppermint can worsen symptoms.
Phenolic acids (hydroxycinnamic acid derivatives)
The phenolic acid fraction, dominated by rosmarinic acid, is responsible for spearmint's potent antioxidant and anti-inflammatory activities. Rosmarinic acid is the primary non-volatile bioactive compound and likely contributes significantly to the anti-androgenic and neuroprotective effects observed in clinical studies. The Herrlinger et al. (2018) cognitive enhancement RCT used a spearmint extract specifically standardized to high rosmarinic acid content, suggesting that the polyphenolic fraction, rather than the essential oil alone, drives the nootropic effect. Rosmarinic acid's anti-inflammatory action complements the essential oil's local carminative effects, providing systemic anti-inflammatory benefit when spearmint is consumed as tea or extract.
Flavonoids
The flavonoid fraction contributes to spearmint's antioxidant, anti-inflammatory, and neuroprotective activities. Luteolin in particular is a significant bioactive flavone with multi-target anti-inflammatory mechanisms (NF-kB inhibition, COX-2 suppression, mast cell stabilization). The combination of luteolin's GABA-modulating properties with apigenin's anxiolytic activity at GABA-A receptors may help explain the traditional use of spearmint tea as a mild calming agent. Flavonoids also contribute to the overall polyphenol antioxidant capacity that synergizes with rosmarinic acid.
Additional volatile compounds
The sesquiterpene fraction is a minor but pharmacologically interesting component of spearmint essential oil. Beta-caryophyllene's activity as a CB2 receptor agonist contributes anti-inflammatory and analgesic effects that complement the primary monoterpenoid pharmacology. These compounds are present in modest quantities and their contribution to overall therapeutic activity is secondary to carvone and the polyphenol fraction.
Vitamins and minerals
The vitamin and mineral content of spearmint is nutritionally modest at typical herbal tea consumption levels but contributes to the overall health-supporting profile of regular spearmint consumption. The iron and manganese content is more relevant in populations that consume spearmint regularly in culinary quantities (as in Middle Eastern and North African cuisine).
Herbal Actions
Relieves intestinal gas and bloating
Spearmint is one of the classic carminative herbs. The essential oil, dominated by carvone, relaxes gastrointestinal smooth muscle and promotes expulsion of intestinal gas. Carvone acts via calcium channel modulation and direct smooth muscle relaxation in the GI tract. Spearmint tea is widely consumed across Mediterranean, Middle Eastern, and European cultures specifically for post-meal digestive comfort, bloating relief, and flatulence. The carminative action is milder than peppermint's (due to absence of menthol) but is generally better tolerated by individuals with GERD or esophageal reflux, as spearmint does not relax the lower esophageal sphincter as strongly as peppermint.
[1, 2, 5]Relieves smooth muscle spasm
Carvone and the essential oil fraction demonstrate smooth muscle antispasmodic activity, particularly in the gastrointestinal tract. This underpins spearmint's traditional use for abdominal cramps, colic, and intestinal spasm. The antispasmodic effect is clinically relevant but milder than peppermint's menthol-mediated antispasmodic action. Preclinical studies demonstrate inhibition of acetylcholine-induced and barium chloride-induced intestinal smooth muscle contractions by spearmint essential oil and aqueous extract.
[1, 5]Kills or inhibits the growth of microorganisms
Spearmint essential oil demonstrates broad-spectrum antimicrobial activity against both Gram-positive and Gram-negative bacteria, as well as several fungi. Carvone, limonene, and 1,8-cineole all contribute to antimicrobial effects. In vitro studies show activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, and various foodborne pathogens. The essential oil also disrupts biofilm formation of Vibrio species. Clinically, the antimicrobial action supports spearmint's traditional use for oral health (mouthwash, breath freshening) and mild gastrointestinal infections.
[5, 11]Prevents or slows oxidative damage to cells
Spearmint leaf demonstrates potent antioxidant activity attributable primarily to its rich polyphenolic content, especially rosmarinic acid and flavonoids (luteolin, eriocitrin). Multiple in vitro assays (DPPH, ABTS, FRAP, ORAC) confirm strong radical scavenging and reducing power. Rosmarinic acid alone is one of the most potent plant-derived antioxidants. The antioxidant capacity of spearmint extract is comparable to or exceeds that of many widely consumed antioxidant-rich herbs and teas. This antioxidant activity is relevant to the neuroprotective, hepatoprotective, and anti-inflammatory effects observed in pharmacological studies.
[5, 8]Reduces inflammation
Multiple constituents contribute to anti-inflammatory activity: rosmarinic acid inhibits complement, lipoxygenase, and cyclooxygenase; luteolin suppresses NF-kB and pro-inflammatory cytokine production; carvone inhibits inflammatory mediator release. In vivo studies demonstrate suppression of carrageenan-induced paw edema and other inflammatory models. The anti-inflammatory action supports spearmint's use in digestive inflammation, menstrual cramps, and inflammatory skin conditions.
[5]Enhances cognitive function, memory, and mental performance
A clinically distinctive action of spearmint supported by the Herrlinger et al. (2018) RCT. A spearmint extract standardized for high rosmarinic acid content (Neumentix, 900 mg/day) significantly improved working memory and spatial working memory accuracy in adults with age-associated memory impairment. A subsequent RCT (Falcone et al. 2019) demonstrated attention-enhancing effects in healthy young adults. The nootropic mechanism is attributed to rosmarinic acid's neuroprotective and antioxidant activity in the CNS, potentially including enhancement of brain-derived neurotrophic factor (BDNF) and modulation of cholinergic signaling.
[8, 9]Promotes perspiration
Hot spearmint tea promotes mild perspiration, a traditional action attributed to aromatic mint teas. Used in folk medicine to support fever management and promote surface circulation during colds and influenza. The diaphoretic effect is gentle and well-suited for children and sensitive individuals.
[1, 4]Supports and calms the nervous system
Spearmint tea is traditionally considered a mild nervine relaxant, promoting a sense of calm without significant sedation. The flavonoid apigenin (GABA-A receptor partial agonist) and the overall aromatic quality contribute to this gentle nervine action. Spearmint is milder than dedicated nervine herbs (valerian, passionflower, lemon balm) but its widespread cultural use as a calming tea across the Mediterranean and Middle East reflects this traditional perception. The Herrlinger et al. (2018) trial also noted improved ability to fall asleep in the spearmint extract group.
[1, 4, 8]Stimulates or increases menstrual flow
Traditional classification as a mild emmenagogue, promoting menstrual flow when delayed or scanty. This action is attributed to the aromatic volatile oil components and their effect on uterine smooth muscle and pelvic circulation. The emmenagogue action is mild and historical; spearmint is not considered a potent uterine stimulant. This traditional action is consistent with its use in menstrual complaints and is supported by its documented hormonal-modulating effects (anti-androgenic activity).
[1, 4]Therapeutic Indications
Endocrine System
Hyperandrogenism and polycystic ovary syndrome (PCOS)
The clinically distinctive indication for spearmint that differentiates it from other mint species. Grant (2010) conducted a 30-day RCT in 42 women with PCOS randomized to spearmint tea (two cups daily) vs. placebo herbal tea. Spearmint tea significantly reduced free testosterone levels and increased luteinizing hormone (LH), follicle-stimulating hormone (FSH), and estradiol compared to placebo, demonstrating clear anti-androgenic hormonal effects. This confirmed and expanded on the earlier pilot study by Akdogan et al. (2007) in 21 women with hirsutism (12 PCOS, 9 idiopathic), which also showed significant reduction in free testosterone after 5 days of spearmint tea consumption. The anti-androgenic mechanism likely involves modulation of steroidogenic enzymes, potentially including inhibition of 5-alpha-reductase and/or effects on the hypothalamic-pituitary-gonadal axis. Guney et al. (2006) demonstrated in a rat model that spearmint induced changes in steroidogenic enzyme expression (decreased cytochrome P450scc, P450C17, and 3-beta-HSD).
[6, 7, 10]Hirsutism (mild to moderate, androgen-related)
Both the Akdogan et al. (2007) and Grant (2010) studies demonstrated significant reduction in free testosterone with spearmint tea consumption in women with hirsutism. However, Grant (2010) notably found that while hormone levels changed significantly within the 30-day study period, the objective Ferriman-Galwey hirsutism scores did not change significantly (p = 0.12). This is consistent with the known biology of androgen-dependent hair follicles, which have long growth cycles -- several months of sustained anti-androgen treatment are typically required before visible reduction in hair growth. The hormonal changes support the mechanism, but clinical hair reduction likely requires longer-term use (3-6+ months).
[6, 7]Digestive System
Flatulence and intestinal gas
One of the oldest and most universally recognized indications for spearmint. The carvone-rich essential oil relaxes gastrointestinal smooth muscle and promotes expulsion of trapped gas. This is a well-established traditional use supported by the pharmacological profile (carminative, antispasmodic actions) and endorsed by the Commission E, ESCOP, and traditional pharmacopeial monographs for Mentha species. Spearmint tea after meals is a widespread practice across Mediterranean, Middle Eastern, and European cultures for this exact purpose.
[1, 2, 5]Dyspepsia (indigestion) and bloating
Closely related to the carminative indication. Spearmint's antispasmodic and carminative actions relieve the fullness, discomfort, and distension associated with functional dyspepsia. Traditional use is extensive and supported by the pharmacological profile. Less clinical trial evidence specifically for spearmint compared to peppermint in dyspepsia, but the mechanistic basis and traditional evidence are strong.
[1, 2, 5]Nausea (mild, including morning sickness)
Spearmint tea is traditionally used as a gentle anti-emetic, particularly for nausea associated with morning sickness, travel sickness, and digestive upset. The aromatic volatile oil components are considered anti-emetic via their action on gastrointestinal smooth muscle and potentially via central mechanisms (aroma therapy effect). Spearmint is often preferred over peppermint for nausea in pregnancy because it is milder and less likely to aggravate reflux. However, controlled clinical trial evidence specific to spearmint for nausea is limited.
[1, 4]Infantile colic and pediatric digestive discomfort
Spearmint tea (weak infusion) has a long traditional history of use for infantile colic and childhood stomachache across many cultures. Its milder flavor and gentler action compared to peppermint make it more suitable for children. Grieve's 'A Modern Herbal' (1931) notes spearmint's historical use for 'allaying nausea and vomiting and will relieve the pain of colic' in children.
[1, 4]Nervous System
Age-associated memory impairment and cognitive decline
Herrlinger et al. (2018) conducted a randomized, double-blind, placebo-controlled trial (n=90) evaluating spearmint extract (Neumentix, standardized for rosmarinic acid) at 900 mg/day, 600 mg/day, or placebo for 90 days in adults with age-associated memory impairment. The 900 mg/day group showed 15% improvement in quality of working memory (p=0.047) and 9% improvement in spatial working memory accuracy (p=0.046) versus placebo. Subjects also reported improved ability to fall asleep (p=0.005). A subsequent RCT by Falcone et al. (2019) confirmed attention-enhancing effects in healthy young adults.
[8, 9]Mild anxiety and nervous tension
Spearmint tea is traditionally consumed as a mild calming agent across Mediterranean and Middle Eastern cultures. The gentle nervine action is attributed to aromatic volatile compounds and flavonoids (apigenin, luteolin). While no dedicated clinical trials have evaluated spearmint specifically for anxiety disorders, the widespread cultural use and the pharmacological profile (GABA-modulating flavonoids, aromatic calming effect) support this traditional indication.
[1, 4]Reproductive System
Menstrual cramps (dysmenorrhea)
Traditional use of spearmint tea for menstrual cramps and discomfort, leveraging its antispasmodic action on smooth muscle. The anti-androgenic properties also provide a theoretical hormonal-modulating rationale for use in menstrual irregularity associated with androgen excess. Traditionally combined with other emmenagogue and antispasmodic herbs (ginger, chamomile, raspberry leaf) for menstrual support.
[1, 4]Hormonal acne (androgen-related)
Given the demonstrated anti-androgenic effects (free testosterone reduction), spearmint tea is increasingly recommended by integrative practitioners for androgen-related acne in women. The rationale is analogous to the anti-androgen pharmaceutical spironolactone, which reduces androgen-driven sebaceous gland activity. Clinical evidence is currently limited to the hormonal data from the Grant (2010) and Akdogan et al. (2007) trials and anecdotal practitioner reports. Dedicated RCTs evaluating spearmint for acne outcomes specifically are needed.
[6, 7]Respiratory System
Common cold, nasal congestion, and upper respiratory symptoms
Spearmint tea is traditionally consumed during colds and influenza for its mild diaphoretic (sweat-promoting) and decongestant effects. The aromatic volatile oils (carvone, 1,8-cineole) provide a subjective sensation of nasal and respiratory clearing. Steam inhalation of spearmint infusion is used for nasal congestion. The antimicrobial action of the essential oil provides supportive activity against respiratory pathogens.
[1, 4, 5]Skin / Integumentary
Oral health (halitosis, gingivitis)
Spearmint's antimicrobial essential oil and pleasant flavor make it one of the most widely used herbs in oral care products (toothpaste, mouthwash, chewing gum). The antimicrobial action of carvone and other essential oil components suppresses oral pathogens (Streptococcus mutans, Porphyromonas gingivalis). This is primarily a topical antimicrobial application rather than a systemic therapeutic indication.
[5]Energetics
Temperature
cool
Moisture
slightly dry
Taste
Tissue States
hot/excitation, damp/stagnation, wind/tension
Spearmint's energetic profile is cool and slightly dry with pungent, aromatic, and sweet tastes. The cooling quality is gentler than peppermint (which is cold) due to the absence of menthol; spearmint cools through its aromatic-dispersive action rather than through direct menthol-mediated cold receptor activation. The pungent-aromatic taste reflects the volatile essential oil (carvone, limonene) and drives spearmint's carminative, diaphoretic, and dispersive actions. The underlying sweetness reflects a mild tonic, nourishing quality consistent with its safety for long-term daily consumption. Spearmint addresses hot/excitation tissue states (inflammation, irritation, hormonal excess/androgen excess), damp/stagnation states (digestive sluggishness, bloating, intestinal gas), and wind/tension states (cramping, spasm, nervous tension). Its cooling, dispersive nature makes it particularly suited to individuals with warm constitutions, heated digestive complaints, or conditions of hormonal excess (hyperandrogenism). CAVEAT: Herbal energetics are interpretive frameworks within Western herbalism and are not standardized across all practitioners.
Traditional Uses
European folk medicine and Western herbalism
- Infusion (tea) for flatulence, indigestion, colic, and stomach cramps
- Mild diaphoretic tea for colds, fevers, and influenza
- Anti-emetic for nausea, including morning sickness and travel sickness
- Weak infusion for infantile colic and childhood digestive complaints
- Poultice of crushed leaves applied to insect bites, minor burns, and skin irritation
- Mild emmenagogue for delayed or scanty menses
- Breath freshener and oral hygiene (chewing fresh leaves)
"Mrs. M. Grieve's A Modern Herbal (1931): 'Spearmint is used for similar purposes to those for which Peppermint is employed, being rather less powerful in its action... It is principally employed for its carminative properties, being useful in relieving flatulence and as a vehicle and flavouring agent for other medicines.' She notes its use 'for allaying nausea and vomiting and will relieve the pain of colic, especially in children.' Grieve further records that spearmint was cultivated in English convent and monastery gardens from the 9th century onward."
Mediterranean and Middle Eastern traditional medicine (Unani, Islamic medicine)
- Daily mint tea (nana) as a digestive tonic after meals across North Africa and the Middle East
- Moroccan mint tea (thé à la menthe) combining green tea with fresh spearmint as a hospitality drink and digestive aid
- Treatment of hiccups, nausea, and stomach pain
- Respiratory support during colds and catarrh
- Applied topically for headache relief (crushed leaves on temples)
- Cooling drink preparation for heat-related complaints in hot climates
- Culinary seasoning in yogurt, salads, and grain dishes for both flavor and digestive benefit
"In Unani (Greco-Arabic) medicine, spearmint is classified as having a cooling temperament (mizaj) and is prescribed for heat-related conditions of the stomach and liver. Ibn Sina (Avicenna) in his Canon of Medicine references mint (na'na') for strengthening the stomach, relieving nausea, and stopping hiccups. The tradition of daily mint tea consumption across North Africa and the Levant represents one of the largest ongoing traditional herbal medicine practices in the world, with millions of cups consumed daily."
Ayurvedic and South Asian traditional medicine
- Treatment of digestive complaints including dyspepsia, flatulence, and diarrhea
- Relief of cholera-related digestive symptoms (historical use in India and Nepal)
- Applied as a paste for skin conditions and insect bites
- Used for urinary retention and as a mild diuretic
- Included in formulations for respiratory conditions (cough, asthma)
- Used as a culinary spice with recognized medicinal digestive properties (chutney, raita)
"In Indian traditional medicine, pudina (spearmint/mint) is used to remedy flatulence and digestive disorders. In Nepal and parts of India, it has been used to treat cholera, dysentery, diarrhea, and urine retention. The Ayurvedic classification considers mint to be pungent (katu) and cooling (sheeta virya) with a pungent post-digestive effect (katu vipaka), suitable for pacifying pitta and kapha doshas."
[5]
Classical Greco-Roman medicine
- Strengthening the stomach and promoting digestion
- Stopping hiccups and eructation (belching)
- Anti-emetic for nausea and vomiting
- Promoting or regulating menstruation
- Applied externally for headache and skin complaints
- Used as a strewing herb and flavoring agent
"Dioscorides (De Materia Medica, ca. 65 CE) describes hedyosmon (mint, likely including spearmint) as warming the stomach, being anti-emetic, useful for hiccups, and aiding digestion. Pliny the Elder (Naturalis Historia, 77 CE) noted that mint 'stirs up the appetite' and 'stops vomiting.' Roman cultivation of mint throughout their empire is well documented, and mint gardens were established across Europe during the Roman period. The Latin name 'mentha' derives from the Greek mythological nymph Minthe."
Modern Research
Anti-androgenic effects of spearmint tea in PCOS (randomized controlled trial)
Grant (2010) conducted a two-center, 30-day RCT in 42 women with PCOS, randomized to spearmint tea (one cup brewed from 5 g dried spearmint, twice daily) versus placebo herbal tea (chamomile). Serum androgen levels, gonadotropins, and hirsutism measures were assessed at days 0, 15, and 30.
Findings: Spearmint tea produced significant reductions in free testosterone levels compared to placebo (P < 0.05). LH and FSH levels increased significantly in the spearmint group. Total testosterone and DHEA-S levels showed non-significant trends toward reduction. Subjective hirsutism (modified DQLI questionnaire) improved in the spearmint group, but the objective Ferriman-Galwey hirsutism score did not change significantly (p = 0.12) over the 30-day period, consistent with the known long growth cycle of androgen-dependent hair follicles. The study confirmed the anti-androgenic hormonal effect previously suggested by Akdogan et al. (2007) and demonstrated that a simple, readily available herbal tea can produce measurable hormonal changes.
Limitations: Relatively small sample size (n=42). Short study duration (30 days) was insufficient to demonstrate clinical reduction in hirsutism (hair follicle turnover requires months). Chamomile used as placebo may not be pharmacologically inert. Single ethnic population (Turkish). Did not measure carvone or polyphenol intake. Longer-term trials (3-6 months minimum) are needed to assess clinical hirsutism outcomes.
[6]
Spearmint tea and androgen levels in hirsute women (pilot study)
Akdogan et al. (2007) conducted a pilot study in 21 women with hirsutism (12 with PCOS, 9 with idiopathic hirsutism). Participants consumed spearmint tea (one cup brewed from 5 g dried M. spicata) twice daily for 5 days during the follicular phase of their menstrual cycles. Serum androgen levels were measured before and after treatment.
Findings: After 5 days of spearmint tea consumption, there was a significant decrease in free testosterone (P < 0.05) and a significant increase in LH, FSH, and estradiol levels (P < 0.05). Total testosterone and DHEA-S showed non-significant decreases. The study provided the first clinical evidence that spearmint tea has anti-androgenic hormonal effects in women and laid the groundwork for the subsequent Grant (2010) RCT.
Limitations: Pilot study design without placebo control. Very short duration (5 days). Small sample size (n=21). No blinding. No assessment of clinical outcomes (hirsutism scores, acne). Hormonal changes at 5 days may not reflect long-term effects.
[7]
Anti-androgenic mechanism of spearmint in rat model
Guney et al. (2006) investigated the mechanism of spearmint's anti-androgenic effects using a rat model. Male rats were administered spearmint tea for 20 and 40 days, and the effects on testicular tissue, steroidogenic enzymes, and hormone levels were assessed.
Findings: Spearmint administration induced oxidative stress in the hypothalamic region and demonstrated testicular anti-androgenic effects. RT-PCR and immunoblot analysis showed decreased expression of key steroidogenic enzymes: cytochrome P450scc (cholesterol side-chain cleavage), cytochrome P450C17, and 3-beta-hydroxysteroid dehydrogenase (3-beta-HSD). Activities of endogenous antioxidant enzymes (SOD, catalase, GPx, glutathione reductase) were decreased in the hypothalamus of treated rats. These findings suggest that spearmint's anti-androgenic effects may be mediated through suppression of steroidogenic enzyme expression, potentially via oxidative stress pathways in the hypothalamus and gonadal tissue.
Limitations: Animal model (male rats) -- results may not directly translate to the female human PCOS context. Supraphysiological doses relative to typical human tea consumption. The oxidative stress mechanism observed in rats raises questions about long-term safety at high doses, though human clinical trials have not shown adverse effects. Male reproductive toxicity in rats should not be extrapolated to female human therapeutic use without caution.
[10]
Spearmint extract improves working memory in age-associated memory impairment (RCT)
Herrlinger et al. (2018) conducted a randomized, double-blind, placebo-controlled trial evaluating a proprietary spearmint extract (Neumentix) standardized for high rosmarinic acid content in adults with age-associated memory impairment (AAMI). Ninety subjects (67% female, mean age 59 years) were randomized to 900 mg/day, 600 mg/day, or placebo for 90 days. Cognitive outcomes were assessed using a computerized test battery.
Findings: The 900 mg/day group showed statistically significant improvement in quality of working memory (+15%, P = 0.047) and spatial working memory accuracy (+9%, P = 0.046) compared to placebo. The 600 mg/day group showed trends toward improvement but did not reach statistical significance for most measures. Additionally, subjects in the 900 mg/day group reported significantly improved ability to fall asleep compared to placebo (P = 0.005). Active reaction time also showed improvement. The cognitive-enhancing effects were attributed to the high polyphenolic content, particularly rosmarinic acid's neuroprotective and antioxidant effects in the CNS.
Limitations: Moderate sample size (n=90 across three arms, ~30 per group). Proprietary extract (Neumentix) standardized for rosmarinic acid -- results may not generalize to standard spearmint tea or other preparations. 90-day duration; longer-term cognitive outcomes unknown. Industry-funded study (Kemin Industries). AAMI population; effects in healthy young adults or clinical cognitive impairment may differ.
[8]
Attention-enhancing effects of spearmint extract in healthy adults (RCT)
Falcone et al. (2019) conducted a randomized, double-blind, placebo-controlled, parallel trial evaluating the attention-enhancing effects of the same proprietary spearmint extract (Neumentix, 900 mg/day) in healthy men and women for 90 days.
Findings: Spearmint extract supplementation improved sustained attention and attentional processing in healthy young adults. The findings extended the Herrlinger et al. (2018) results to a younger, cognitively healthy population, suggesting that the nootropic effects of spearmint extract are not limited to individuals with existing cognitive impairment.
Limitations: Industry-funded. Proprietary extract preparation. Moderate sample size. Short-term outcomes only.
[9]
Comprehensive review of spearmint phytochemistry, pharmacology, and traditional uses
Mahendran et al. (2021) published a comprehensive review in the Journal of Ethnopharmacology covering the traditional uses, phytochemistry, and pharmacology of Mentha spicata. The review synthesized data on essential oil composition, polyphenol content, antimicrobial, antioxidant, anti-inflammatory, anticancer, and hepatoprotective activities.
Findings: The review confirmed carvone as the dominant essential oil compound (typically 50-70%) with significant chemotypic variation globally. It catalogued extensive traditional use across Mediterranean, Middle Eastern, South Asian, and European folk medicine for digestive complaints, respiratory symptoms, and skin conditions. Pharmacological evidence supported antimicrobial activity against both Gram-positive and Gram-negative bacteria and several fungi. Antioxidant, anti-inflammatory, and hepatoprotective effects were documented across multiple in vitro and in vivo models. The review concluded that pharmacological properties supported the traditional uses of spearmint.
Limitations: Narrative review, not a systematic review with formal quality assessment methodology. Heterogeneity of preparations, doses, and models across cited studies. Many pharmacological studies used essential oil or isolated compounds rather than the whole herb preparations used in clinical practice. Limited coverage of human clinical trial data.
[5]
Antimicrobial and antibiofilm activity of spearmint essential oil
Neves et al. (2018) investigated the antimicrobial and antibiofilm activity of M. spicata essential oil against planktonic and biofilm cultures of Vibrio species, alongside chemical composition analysis.
Findings: The essential oil contained carvone (40.8%), limonene (20.8%), and 1,8-cineole (17.0%) as major components, with 50.6% oxygenated monoterpenes and 45.1% monoterpene hydrocarbons. The oil demonstrated significant antimicrobial activity against multiple Vibrio species in planktonic form and, importantly, disrupted preformed biofilms. Minimum inhibitory concentrations ranged from 0.25-1.0 mg/mL depending on the species tested. The antibiofilm activity is particularly significant as biofilm-forming bacteria are often resistant to conventional antimicrobial agents.
Limitations: In vitro study. Activity against Vibrio species specifically -- clinical relevance is primarily to foodborne and waterborne pathogens. Concentrations used in vitro may not be achievable through dietary spearmint consumption. Essential oil tested, not whole herb or tea preparations.
[11]
Medicinal uses, phytochemistry, pharmacology, and toxicology of Mentha spicata (review)
Bardaweel et al. (2022) published a comprehensive review in the journal Antioxidants covering the medicinal uses, detailed phytochemistry, pharmacological activities, and toxicological profile of Mentha spicata, with emphasis on safety data.
Findings: The review confirmed the broad pharmacological profile of M. spicata including antimicrobial, antioxidant, anti-inflammatory, anticancer, antidiabetic, and neuroprotective activities. It detailed the essential oil chemotypes and noted that carvone-rich chemotypes are most commercially valuable and most widely studied. The toxicological review found that spearmint is generally regarded as safe (GRAS) by the FDA, with no significant acute or chronic toxicity at dietary exposure levels. The review noted the animal data (Guney et al. 2006, Akdogan et al. 2004) showing reproductive effects in male rats at high doses but emphasized that these findings have not been replicated in human studies and are at doses far exceeding normal consumption.
Limitations: Narrative review format. Toxicological data largely from animal studies with limited human safety data from controlled trials.
[12]
Preparations & Dosage
Infusion (Tea)
Strength: 1.5-5 g dried herb per 200-250 mL water. Standard ratio approximately 1:60-1:100 (herb:water by weight)
Place 1-2 teaspoons (1.5-3 g) of dried spearmint leaf, or 2-3 tablespoons (approximately 6-10 g) of fresh leaves, in a cup or teapot. Pour 200-250 mL of freshly boiled water over the herb. Cover immediately to prevent volatile oil loss (this is important -- an uncovered infusion loses significant essential oil to evaporation). Steep for 5-10 minutes. Strain and drink. For a stronger therapeutic infusion, use 2-3 teaspoons of dried herb and steep for 10-15 minutes.
1-2 cups (200-500 mL) of infusion, 2-3 times daily. For anti-androgenic purposes (PCOS/hirsutism), the clinical trial protocol used 5 g dried spearmint steeped in one cup of boiling water, consumed twice daily (Grant 2010).
2-3 times daily, preferably after meals for digestive indications. For PCOS/anti-androgenic use: twice daily consistently.
May be used long-term as a daily beverage. For anti-androgenic effects, consistent daily use for at least 1-3 months is recommended before assessing therapeutic response. Spearmint tea is consumed daily as a lifelong practice by millions across the Mediterranean and Middle East.
Children 2-12 years: half-strength infusion (1/2 to 1 teaspoon dried herb per cup), 1-2 times daily. Spearmint tea is one of the mildest and safest herbal teas for children and has a long history of pediatric use for colic and digestive upset.
Infusion is the traditional and most accessible preparation form for spearmint. The hot water effectively extracts both the volatile essential oil components (carvone, limonene) and the non-volatile polyphenols (rosmarinic acid, flavonoids), providing the full spectrum of bioactive compounds. Covering the vessel during steeping is essential to capture the volatile essential oil in the condensation rather than losing it to the atmosphere. Spearmint infusion has a pleasant, sweet, warm aroma and is far less intensely cooling than peppermint tea, making it more palatable for many individuals. In the Moroccan tea tradition, spearmint is combined with Chinese gunpowder green tea and sugar, which may modify the polyphenol profile through synergistic effects.
Tincture
Strength: 1:5 in 45% ethanol (dried herb) or 1:2 in 75% ethanol (fresh herb)
Use dried or fresh spearmint leaf. For dried herb: macerate 1 part dried herb in 5 parts menstruum (45-60% ethanol) for 2-4 weeks with daily agitation. For fresh herb: macerate 1 part fresh herb in 2 parts menstruum (75-95% ethanol to account for plant moisture). Press, filter, and bottle. Label with herb, ratio, menstruum strength, and date.
2-4 mL (40-80 drops) three times daily
Three times daily, taken in a small amount of water
May be used for extended periods. Reassess therapeutic goals periodically.
Not typically used in children due to alcohol content. Glycerite preparation preferred for pediatric use.
Tincture preserves both the volatile essential oil fraction and the non-volatile polyphenol fraction in a stable, long-lasting preparation with a shelf life of 3-5+ years. The ethanol efficiently extracts carvone, limonene, rosmarinic acid, and flavonoids. Tincture is convenient for standardized dosing and can be added to water or other beverages. The higher alcohol concentration for fresh herb tincture compensates for the plant's water content. For individuals avoiding alcohol, glycerite is an alternative.
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Glycerite
Strength: 1:5 in 60% glycerin/40% water
Macerate 1 part dried spearmint leaf in 5 parts menstruum consisting of 60% vegetable glycerin and 40% water. Macerate for 4-6 weeks with regular agitation. Press and filter. Alternatively, prepare a concentrated infusion and mix 3 parts glycerin with 1 part strained infusion.
3-5 mL three times daily
Two to three times daily
May be used long-term
Children 2-12 years: 1-2 mL two to three times daily. Glycerite is the preferred extraction form for children due to its sweet taste and absence of alcohol.
Glycerite is the preferred alcohol-free preparation for children, pregnant women (at standard doses), and individuals avoiding alcohol. Glycerin extracts water-soluble polyphenols (rosmarinic acid, flavonoids) effectively but is a less efficient solvent for volatile terpenes compared to ethanol. The sweet taste of glycerin makes this preparation highly palatable, especially for children. Shelf life is 1-2 years when refrigerated.
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Capsule / Powder
Strength: Crude powder: 500 mg per capsule. Extract: varies by manufacturer; Neumentix contains 14.5% rosmarinic acid and 24% total polyphenols
Fill vegetarian or gelatin capsules with dried, finely powdered spearmint leaf. Alternatively, encapsulate concentrated spearmint extract powder. The Herrlinger et al. (2018) cognitive trial used a proprietary extract (Neumentix) in capsule form standardized for rosmarinic acid content.
Crude powder: 1-3 g daily in divided doses (2-6 capsules of 500 mg). Concentrated extract: 500-900 mg daily, depending on concentration ratio. For cognitive support (per Herrlinger 2018): 900 mg/day of standardized extract.
Two to three times daily with water, taken with meals
May be used long-term. For cognitive support, the clinical trial duration was 90 days.
Not typically used in capsule form for children (tea or glycerite preferred)
Capsules provide standardized, convenient dosing and are especially relevant for the nootropic/cognitive indication, which was established using a standardized extract rather than traditional tea. For anti-androgenic/PCOS use, the clinical evidence is based on tea consumption rather than capsules, so tea may be preferred for that indication. Products should specify whether they contain crude leaf powder or concentrated extract, and the polyphenol/rosmarinic acid content if available.
Essential Oil
Strength: Pure essential oil (100%). Must be diluted before application. INCI: Mentha Spicata (Spearmint) Oil
For external and aromatherapy use only. Dilute 2-5 drops of spearmint essential oil in 10 mL (2 teaspoons) of carrier oil (e.g., jojoba, sweet almond, coconut) for topical application. For steam inhalation: add 3-5 drops to a bowl of hot water, cover head with towel, and inhale for 5-10 minutes. For diffusion: add 5-10 drops to an ultrasonic or nebulizing diffuser.
Topical: 1-2% dilution (2-5 drops per 10 mL carrier oil). Inhalation: 3-5 drops in hot water or diffuser. Internal use of undiluted essential oil is NOT recommended without guidance from a qualified clinical aromatherapist.
As needed for aromatherapy. Topical application 2-3 times daily as needed.
Short-term topical use. Discontinue if skin irritation occurs.
Children over 6 years: 0.5-1% dilution (1-2 drops per 10 mL carrier oil). Not for use in children under 2 years. Spearmint EO is gentler than peppermint EO for children.
Spearmint essential oil is significantly milder than peppermint essential oil due to the absence of menthol. It does not produce the intense cooling sensation of peppermint oil and is less likely to cause skin irritation or mucous membrane burning. This makes it preferable for use with children and sensitive individuals. The essential oil is widely used in food, pharmaceutical, and cosmetic industries as a flavoring and fragrance agent. The FDA classifies spearmint oil as Generally Recognized as Safe (GRAS) for food use. However, essential oils are highly concentrated (50-100x the concentration in the whole plant) and should be respected accordingly.
Syrup
Strength: Concentrated infusion (approximately 1:10 herb:water) combined 1:1 with honey or sugar
Prepare a concentrated spearmint infusion by steeping 30-50 g of dried spearmint leaf in 500 mL of boiling water for 15-20 minutes in a covered vessel. Strain thoroughly. Measure the liquid and add an equal volume of raw honey or sugar. Gently warm (do not boil) and stir until dissolved. Optionally add a small amount of lemon juice (preservative and flavor). Store refrigerated in a clean glass bottle.
1-2 tablespoons (15-30 mL) two to three times daily, or as needed for sore throat and cough
Two to three times daily or as needed
Short-term (acute respiratory or digestive symptoms). Consume within 2-4 weeks if refrigerated.
Children 2-12 years: 1-2 teaspoons (5-10 mL) two to three times daily. Not for children under 1 year if honey-based (botulism risk).
Spearmint syrup is a pleasant, palatable preparation especially useful for children and for sore throat, cough, and respiratory congestion where the soothing quality of the honey/sugar base complements the aromatic, mildly antimicrobial spearmint. The sweet base also makes this preparation effective for nausea. This is a short-shelf-life preparation (2-4 weeks refrigerated) and should be made in small batches.
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Safety & Interactions
Class 1
Can be safely consumed when used appropriately (AHPA Botanical Safety Handbook)
Contraindications
Individuals with confirmed allergy to spearmint, peppermint, or other members of the Lamiaceae family (basil, rosemary, lavender, thyme, etc.) should avoid spearmint products. Contact dermatitis from spearmint has been reported rarely, typically in occupational settings (food industry workers). Cross-reactivity within the Lamiaceae family is possible.
Drug Interactions
| Drug / Class | Severity | Mechanism |
|---|---|---|
| Anti-androgen medications (spironolactone, flutamide, finasteride, cyproterone acetate) (Anti-androgens) | theoretical | Spearmint has demonstrated anti-androgenic activity in clinical trials (reduction in free testosterone). Co-administration with pharmaceutical anti-androgens could theoretically produce additive androgen-lowering effects. |
| Iron supplements and iron-containing medications (Mineral supplements) | minor | The polyphenol content (rosmarinic acid, caffeic acid, chlorogenic acid) of spearmint can chelate non-heme iron, potentially reducing iron absorption. This is a general property of polyphenol-rich beverages (tea, coffee) rather than a specific spearmint effect. |
| CYP enzyme substrates (theoretical based on essential oil constituents) (Various (CYP3A4, CYP2D6 substrates)) | theoretical | In vitro studies suggest that some Mentha essential oil components (carvone, limonene) may inhibit cytochrome P450 enzymes (CYP3A4, CYP2D6) at high concentrations. However, the concentrations required for significant enzyme inhibition far exceed those achieved through dietary spearmint tea consumption. |
Pregnancy & Lactation
Pregnancy
likely safe
Lactation
likely safe
Spearmint tea at standard dietary and beverage doses (1-2 cups daily) is considered likely safe during pregnancy and lactation based on its extremely long history of use as a common food and beverage plant with no documented pattern of adverse reproductive outcomes. It is one of the most widely consumed herbal teas across cultures, including by pregnant and breastfeeding women, particularly in Mediterranean and Middle Eastern populations where daily mint tea consumption is normative. The AHPA Botanical Safety Handbook (2nd ed., Gardner & McGuffin 2013) classifies Mentha spicata as Class 1 (herbs that can be safely consumed when used appropriately) without specific pregnancy contraindication at food/beverage doses. HOWEVER: (1) Concentrated therapeutic doses aimed at anti-androgenic effects should be approached with caution during pregnancy due to theoretical concerns about androgen modulation in the developing fetus. (2) Spearmint essential oil should NOT be used during pregnancy at therapeutic doses. (3) The traditional mild emmenagogue classification warrants general awareness, though at standard tea doses this effect is not clinically significant.
Adverse Effects
References
Monograph Sources
- [1] Hoffmann D. Medical Herbalism: The Science and Practice of Herbal Medicine. Healing Arts Press, Rochester, Vermont (2003) . ISBN: 978-0892817498
- [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, Texas (1998) . ISBN: 978-0965555500
- [3] Gardner Z, McGuffin M (eds). American Herbal Products Association's Botanical Safety Handbook, 2nd edition. CRC Press/Taylor & Francis, Boca Raton, Florida (2013) . ISBN: 978-1466516946
- [4] Grieve M. A Modern Herbal: The Medicinal, Culinary, Cosmetic and Economic Properties, Cultivation and Folk-lore of Herbs, Grasses, Fungi, Shrubs & Trees with Their Modern Scientific Uses. Jonathan Cape, London (reprinted by Dover Publications, 1971) (1931) . ISBN: 978-0486227986
- [5] Mahendran G, Verma SK, Rahman LU. The traditional uses, phytochemistry and pharmacology of spearmint (Mentha spicata L.): A review. J Ethnopharmacol (2021) ; 278 : 114266 . DOI: 10.1016/j.jep.2021.114266 . PMID: 34087400
Clinical Studies
- [6] Grant P. Spearmint herbal tea has significant anti-androgen effects in polycystic ovarian syndrome. A randomized controlled trial. Phytother Res (2010) ; 24 : 186-188 . DOI: 10.1002/ptr.2900 . PMID: 19585478
- [7] Akdogan M, Tamer MN, Cure E, Cure MC, Koroglu BK, Delibas N. Effect of spearmint (Mentha spicata Labiatae) teas on androgen levels in women with hirsutism. Phytother Res (2007) ; 21 : 444-447 . DOI: 10.1002/ptr.2074 . PMID: 17310494
- [8] Herrlinger KA, Nieman KM, Sanoshy KD, Chamberlin KA, Fonseca BA, Lasrado JA, Schild AL, Maki KC. Spearmint extract improves working memory in men and women with age-associated memory impairment. J Altern Complement Med (2018) ; 24 : 37-47 . DOI: 10.1089/acm.2016.0379 . PMID: 29314866
- [9] Falcone PH, Nieman KM, Tribby AC, Vogel RM, Joy JM, Moon JR, Slayton CA, Henigman MM, Lasrado JA, Lewis BJ, Fonseca BA, Herrlinger KA. The attention-enhancing effects of spearmint extract supplementation in healthy men and women: a randomized, double-blind, placebo-controlled, parallel trial. Nutr Res (2019) ; 64 : 24-38 . DOI: 10.1016/j.nutres.2018.11.012 . PMID: 30802720
- [10] Guney M, Oral B, Karahanoglu E, Mungan T, Akdogan M. The effect of Mentha spicata Labiatae on uterine tissue in rats. Toxicol Ind Health (2006) ; 22 : 461-464 . DOI: 10.1177/0748233706074110 . PMID: 17533779
Traditional Texts
- [11] Neves IA, da Camara CAG, de Oliveira JCS, de Almeida AV. Mentha spicata essential oil: chemical composition, antioxidant and antibacterial activities against planktonic and biofilm cultures of Vibrio spp. strains. Molecules (2018) ; 24 : 31 . DOI: 10.3390/molecules24010031 . PMID: 30577562
- [12] Bardaweel SK, Bakchiche B, ALSalamat HA, Rezzoug M, Gherib A, Flamini G. Medicinal uses, phytochemistry, pharmacology, and toxicology of Mentha spicata. Antioxidants (2022) ; 11 : 1478 . DOI: 10.3390/antiox11081478 . PMID: 36009196
Pharmacopeias & Reviews
- [13] European Directorate for the Quality of Medicines (EDQM). European Pharmacopoeia, 10th edition: Menthae crispae folium (Spearmint leaf). Council of Europe, Strasbourg (2019)
Last updated: 2026-03-02 | Status: review
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