Damiana

In Germany, damiana is used to relieve excess mental activity and nervous debility, and as a tonic for the hormonal and central nervous systems ^{34Reference 34Taylor · 2005The healing power of rainforest herbs: A guide to understanding and using herbal medicinals}.

The British Herbal Pharmacopoeia gives its indications as “anxiety neurosis, with a predominant sexual factor, depression, nervous dyspepsia, atonic constipation, and coital inadequacy” ^{34Reference 34Taylor · 2005The healing power of rainforest herbs: A guide to understanding and using herbal medicinals}. It is also used as a tonic in nervous exhaustion (neurasthenia) ^{33Reference 33Bernardo et al. · 2021In vitroTrichilia catigua and Turnera diffusa extracts: in vitro inhibition of tyrosinase, antiglycation and neuroinflammation — in vitroView study →}.

Around the world the plant has been used as an antidepressant, cough remedy, mild laxative, aphrodisiac, tonic and diuretic. The conditions it has been given for include bedwetting, depression, anxiety, sexual problems, bronchitis, stomach ulcers, menstrual irregularities, constipation, asthma, diabetes, dysentery, indigestion, headaches, paralysis, kidney disease, spermatorrhoea and stomach aches ^{34,35Reference 34Taylor · 2005The healing power of rainforest herbs: A guide to understanding and using herbal medicinalsReference 35Bone · 2003A clinical guide to blending liquid herbs: Herbal formulations for the individual patient}.

Damiana was an aphrodisiac of the Maya ^{38Reference 38Fern · 2026Turnera diffusa — habit, range, habitat, cultivation, edible and medicinal uses — species databaseView study →}, who also used it for giddiness and loss of balance ^{34Reference 34Taylor · 2005The healing power of rainforest herbs: A guide to understanding and using herbal medicinals}.

In Mexico it is used extensively for coughs, as a diuretic and as an aphrodisiac ^{37Reference 37Arbo · 2015Turnera diffusa Willdenow — species and variety description, habitat, distribution and uses — floraView study →}. In Baja California, where it is known as damiana de California, it is also used against infection ^{18Reference 18Reyes-Becerril et al. · 2020In vitroChemical, biological and immunological properties of “Damiana de California” Turnera diffusa extracts in Longfin yellowtail leukocytes — in vitroView study →}. Mexican folk medicine uses it for liver illness and for diabetes as well ^{10,24Reference 10Delgado-Montemayor et al. · 2023In vitroHepatodamianol as hepatoprotective constituent of Turnera diffusa — in vitroView study →Reference 24Parra-Naranjo et al. · 2017Acute hypoglycemic and antidiabetic effect of teuhetenone A isolated from Turnera diffusa — animal studyView study →}.

Antioxidant activity is the most reproducible finding for damiana. A chromatographic-fingerprint study modelled DPPH radical-scavenging across 40 extracts and correctly predicted the activity of 83% of the commercial products tested, tying the effect to the herb’s phenolic profile ^{5Reference 5Garza-Juárez et al. · 2011In vitroCorrelation between chromatographic fingerprint and antioxidant activity of Turnera diffusa (Damiana) — in vitroView study →}.

Wild T. diffusa from arid Tamaulipas, Mexico, held up to about 34 mg gallic-acid equivalents of phenolics per gram, with strong ABTS and FRAP activity that differed between sites ^{6Reference 6Urbizu-González et al. · 2017In vitroNatural variability of essential oil and antioxidants in the medicinal plant Turnera diffusa — in vitroView study →}.

The effect carries into tissue. A water–ethanol extract lowered malondialdehyde and nitric oxide in kidney mitochondria of diabetic rats, though it did not correct their high blood sugar ^{7Reference 7Edgar Romualdo et al. · 2018AnimalAntioxidant effects of damiana (Turnera diffusa) in kidney mitochondria from streptozotocin-diabetic rats — animal modelView study →}. Damiana also reduced lipid peroxidation and restored antioxidant enzymes in the testes of rats exposed to a pesticide and hexavalent chromium ^{17Reference 17El-Demerdash et al. · 2019AnimalModulatory effect of Turnera diffusa against testicular toxicity induced by fenitrothion and/or hexavalent chromium in rats — animal studyView study →}.

An infusion, the traditional tea, had more phenolics and flavonoids and stronger hydroxyl-radical scavenging than a methanol extract in one comparison ^{18Reference 18Reyes-Becerril et al. · 2020In vitroChemical, biological and immunological properties of “Damiana de California” Turnera diffusa extracts in Longfin yellowtail leukocytes — in vitroView study →}.

Gap: every result is from the laboratory or animals, and no antioxidant dose has been defined for people.

This is the herb’s main traditional use and its best-developed animal pharmacology. A T. diffusa fluid extract improved mating performance in sexually sluggish or impotent male rats, but not in sexually potent ones. At 1 mL/kg it increased the share of rats reaching ejaculation and shortened the delays between mating steps, without affecting general activity ^{1Reference 1Arletti et al. · 1999AnimalStimulating property of Turnera diffusa and Pfaffia paniculata extracts on the sexual behavior of male rats — animal studyView study →}.

A chemically characterised aqueous extract (80 mg/kg) restored mating in sexually exhausted rats, much as yohimbine did, and arbutin and flavonoids were among its main compounds ^{8Reference 8Estrada-Reyes et al. · 2009Turnera diffusa recovers sexual behavior in sexually exhausted males — animal studyView study →}.

A follow-up in sexually sluggish rats found that the extract and sildenafil, both at 10 mg/kg, shortened the time to ejaculation. An inhibitor of nitric-oxide synthase blocked both effects, pointing to the nitric-oxide pathway, acting mainly in the brain. The extract also had an anxiety-reducing effect without changing activity ^{9Reference 9Estrada-Reyes et al. · 2013AnimalPro-sexual effects of Turnera diffusa in male rats involves the nitric oxide pathway — animal studyView study →}.

Gap: all efficacy data are from rats. No controlled human trial has tested damiana alone for libido or erectile function.

Damiana’s reputation as a nervine is supported by rodent studies. Of four extracts of T. aphrodisiaca aerial parts tested in the mouse elevated plus-maze, only the methanol extract (25 mg/kg) reduced anxiety-like behaviour. Its butanol fraction was active at 10 mg/kg and the remaining methanol extract at 75 mg/kg ^{20Reference 20Kumar et al. · 2005Anti-anxiety activity studies of various extracts of Turnera aphrodisiaca Ward — animal studyView study →}.

The flavonoid apigenin was isolated as an anxiety-reducing constituent. At 2 mg/kg it reduced anxiety-like behaviour in three mouse models, and it had no antidepressant or anticonvulsant effect. At about twelve times that dose it was mildly sedating, and it relieved pain in a dose-dependent way ^{13Reference 13Kumar et al. · 2008Pharmacological evaluation of bioactive principle of Turnera aphrodisiaca — animal studyView study →}.

An aqueous extract produced clear anxiety-reducing and antidepressant-like effects in mice without affecting movement, and a 28-day toxicology study found no damage to organs ^{12Reference 12Ana María et al. · 2019AnimalNeurobehavioral and toxicological effects of an aqueous extract of Turnera diffusa in mice — animal studyView study →}.

Gap: the evidence is entirely rodent-based. Most of the apigenin in the plant is bound as glycosides, and the flowers hold more than the leaves ^{21Reference 21Kumar et al. · 2008Estimation of apigenin, an anxiolytic constituent, in Turnera aphrodisiacaView study →}.

Arbutin, a major T. diffusa glycoside, protected the stomach lining of rats against aspirin- and ethanol-induced ulcers. It lowered lipid peroxidation (TBARS) and modulated IL-6, IL-10 and TNF-α, did not act through nitric oxide, and showed no toxicity ^{23Reference 23Taha et al. · 2012Gastroprotective activities of Turnera diffusa revisited: role of arbutin — animal studyView study →}.

In the related T. ulmifolia, a hydroalcoholic extract of the aerial parts protected against ulcers caused by indomethacin, ethanol and pylorus ligation in rodents, and it raised protective stomach mucus ^{30Reference 30Antônio et al. · 1998Oral anti-inflammatory and anti-ulcerogenic activities of a hydroalcoholic extract and fractions of Turnera ulmifolia — animal studyView study →}.

Gap: the strongest data are for isolated arbutin rather than whole damiana, and part of the support comes from T. ulmifolia.

Older reports suggested that damiana’s blood-sugar-lowering constituents are water-soluble ^{34Reference 34Taylor · 2005The healing power of rainforest herbs: A guide to understanding and using herbal medicinals}. Bioassay-guided work on a methanol extract of the aerial parts later isolated teuhetenone A, which gradually lowered glucose in normal and diabetic mice. It did not inhibit α-glucosidase ^{24Reference 24Parra-Naranjo et al. · 2017Acute hypoglycemic and antidiabetic effect of teuhetenone A isolated from Turnera diffusa — animal studyView study →}.

In diabetic rats, a water–ethanol extract did not reverse high blood sugar, although it protected kidney mitochondria ^{7Reference 7Edgar Romualdo et al. · 2018AnimalAntioxidant effects of damiana (Turnera diffusa) in kidney mitochondria from streptozotocin-diabetic rats — animal modelView study →}. In a type 2 diabetes rat model, a leaf extract (100–200 mg/kg for 28 days) restored sperm count, motility and testosterone-producing proteins, mainly by reducing oxidative stress and inflammation (NF-κB ↓) ^{25Reference 25Kumar et al. · 2023AnimalOral Turnera diffusa extract ameliorates steroidogenesis and spermatogenesis impairment in the testes of type-2 diabetic rats — animal studyView study →}.

Gap: results depend on the dose and the fraction, and several studies found organ protection without any fall in blood glucose.

Bioassay-guided fractionation of a methanol extract of the aerial parts isolated the C-glycoside hepatodamianol. It protected HepG2 liver cells against carbon tetrachloride about four times more than silibinin, with high antioxidant capacity and no toxicity to the cells ^{10Reference 10Delgado-Montemayor et al. · 2023In vitroHepatodamianol as hepatoprotective constituent of Turnera diffusa — in vitroView study →}.

A methanol extract also lowered scarring markers (α-SMA, COL1α1, TIMP1) in activated human liver stellate cells ^{11Reference 11Rodríguez-Rodríguez et al. · 2021In vitroTurnera diffusa extract attenuates profibrotic, extracellular matrix and mitochondrial markers in activated human hepatic stellate cells — in vitroView study →}.

Gap: both studies are in cell cultures. No animal or human liver study has been done.

A methanol extract of damiana leaves inhibited aromatase (IC₅₀ 63.1 µg/mL). Of 24 compounds isolated from the leaves, the flavonoids pinocembrin and acacetin were the strongest aromatase inhibitors (IC₅₀ 10.8 and 18.7 µM), while apigenin 7-glucoside, Z-echinacin and pinocembrin were estrogenic in a yeast screen ^{15Reference 15Zhao et al. · 2008In vitroAnti-aromatase activity of the constituents from damiana (Turnera diffusa) — in vitroView study →}.

A computer docking study found three damiana compounds that bind strongly to estrogen receptors ^{16Reference 16Powers et al. · 2015A molecular docking study of phytochemical estrogen mimics from dietary herbal supplements — in silicoView study →}, and damiana is grouped with other estrogenic plants in a review on menopause ^{26Reference 26Echeverria et al. · 2021ReviewEstrogenic plants to prevent neurodegeneration and memory loss after menopause — reviewView study →}.

In a pilot study, 15 women with irregular cycles who were breast-cancer survivors or at high genetic risk took damiana combined with wild yam and chaste tree. Their cycles became regular and menstrual pain eased, but damiana’s own part cannot be separated ^{27Reference 27Grandi et al. · 2023Phyto-progestins for abnormal uterine bleeding in women at high risk for breast cancer — pilot studyView study →}.

Gap: the evidence is at the level of isolated flavonoids, enzyme tests and docking. A whole-herb estrogenic effect in the body is unproven.

Damiana itself has been tested against bacteria in a few lab studies. In a comparison of common medicinal plant extracts against Staphylococcus aureus, damiana was one of the “highly effective” group, which both stopped bacterial growth and killed the bacteria at higher concentrations ^{39Reference 39Snowden R et al. · 2014In vitroA comparison of the anti-Staphylococcus aureus activity of extracts from commonly used medicinal plants — in vitroView study →}. At lower doses its effect faded and the bacteria recovered ^{39Reference 39Snowden R et al. · 2014In vitroA comparison of the anti-Staphylococcus aureus activity of extracts from commonly used medicinal plants — in vitroView study →}.

A damiana infusion and a methanol extract both inhibited Vibrio parahaemolyticus ^{18Reference 18Reyes-Becerril et al. · 2020In vitroChemical, biological and immunological properties of “Damiana de California” Turnera diffusa extracts in Longfin yellowtail leukocytes — in vitroView study →}. It is a pathogen of farmed fish, and also a leading cause of food poisoning from raw or undercooked seafood in people ^{40Reference 40Su YC · 2007ReviewVibrio parahaemolyticus: a concern of seafood safety — reviewView study →}. Damiana essential oil was tested against 15 strains of mycobacteria, the group that includes tuberculosis, and was less active than a sage oil (Salvia aratocensis) tested alongside it ^{41Reference 41Bueno J et al. · 2011In vitroComposition of three essential oils, and their mammalian cell toxicity and antimycobacterial activity against drug resistant-tuberculosis and nontuberculous mycobacteria strains — in vitroView study →}.

The antibiotic-boosting findings come from a related species, Turnera ulmifolia. An ethanol extract of T. ulmifolia boosted gentamicin and kanamycin against MRSA ^{28Reference 28Coutinho et al. · 2009In vitroHerbal therapy associated with antibiotic therapy: potentiation against MRSA by Turnera ulmifolia — in vitroView study →}. It did not inhibit multidrug-resistant E. coli on its own, but it increased the effect of amikacin, neomycin and tobramycin ^{29Reference 29Coutinho et al. · 2010In vitroIncreasing aminoglycoside activity against multidrug-resistant E. coli by Turnera ulmifolia and chlorpromazine — in vitroView study →}. Parallel results with chlorpromazine point to an efflux pump in the bacteria ^{28,29Reference 28Coutinho et al. · 2009In vitroHerbal therapy associated with antibiotic therapy: potentiation against MRSA by Turnera ulmifolia — in vitroView study →Reference 29Coutinho et al. · 2010In vitroIncreasing aminoglycoside activity against multidrug-resistant E. coli by Turnera ulmifolia and chlorpromazine — in vitroView study →}.

Reviews of the genus list antibacterial and antimycobacterial activity across Turnera ^{3Reference 3Szewczyk et al. · 2014ReviewEthnobotany, phytochemistry, and bioactivity of the genus Turnera with a focus on damiana — reviewView study →}.

Gap: the potentiation data are for T. ulmifolia, the work is in vitro, and the efflux-pump mechanism is inferred rather than shown for damiana.

A hydroalcoholic extract of T. ulmifolia aerial parts reduced carrageenan paw swelling and cotton-pellet granuloma in rodents and blocked vessel leakage caused by histamine, serotonin and prostaglandin E2 ^{30Reference 30Antônio et al. · 1998Oral anti-inflammatory and anti-ulcerogenic activities of a hydroalcoholic extract and fractions of Turnera ulmifolia — animal studyView study →}. A flower extract of another species, T. subulata, had pain-relieving, anti-inflammatory and blood-sugar-lowering effects in zebrafish ^{31Reference 31Rebouças et al. · 2022Antinociceptive, anti-inflammatory and hypoglycemic activities of the ethanolic Turnera subulata Sm. flower extract in adult zebrafish (Danio rerio) — animal studyView study →}.

For T. diffusa itself, a leaf extract lowered NF-κB, p-IKKβ and TNF-α and raised IκBα in the testes of diabetic rats ^{25Reference 25Kumar et al. · 2023AnimalOral Turnera diffusa extract ameliorates steroidogenesis and spermatogenesis impairment in the testes of type-2 diabetic rats — animal studyView study →}. Its isolated flavonoid apigenin relieved pain in mice ^{13Reference 13Kumar et al. · 2008Pharmacological evaluation of bioactive principle of Turnera aphrodisiaca — animal studyView study →}.

Gap: most of the anti-inflammatory evidence comes from other Turnera species.

Of five medicinal plants screened, an aqueous damiana extract was the most active on nervous-system targets. It inhibited monoamine oxidase-A and, given beforehand, protected SH-SY5Y nerve cells against glutamate damage, partly through antioxidant effects ^{32Reference 32Bernardo et al. · 2017In vitroTurnera diffusa inhibits CNS enzymes and delays glutamate excitotoxicity in SH-SY5Y cells — in vitroView study →}.

In a comparison with Trichilia catigua, a damiana extract rich in luteolin derivatives was weaker at inhibiting tyrosinase and 5-lipoxygenase, but it was the only one that lowered nitric-oxide production by stimulated microglia ^{33Reference 33Bernardo et al. · 2021In vitroTrichilia catigua and Turnera diffusa extracts: in vitro inhibition of tyrosinase, antiglycation and neuroinflammation — in vitroView study →}.

Gap: this is all cell and enzyme work, with no animal or human cognition data.

A methanol extract of T. diffusa was cytotoxic to five tumour cell lines, most strongly MDA-MB-231 breast-cancer cells (IC₅₀ about 30.7 µg/mL). Arbutin and apigenin were isolated from the most active fraction ^{14Reference 14Avelino-Flores et al. · 2015In vitroCytotoxic activity of the methanolic extract of Turnera diffusa on breast cancer cells — in vitroView study →}.

Gap: this is a single cell-line study, with no animal tumour model and no test of selectivity.

Animal toxicity. In a 28-day study in mice, an aqueous extract caused no behavioural side effects and no damage to target organs, only a sex-dependent reduction in weight gain; in a 35-day study it did not harm sperm quality ^{12Reference 12Ana María et al. · 2019AnimalNeurobehavioral and toxicological effects of an aqueous extract of Turnera diffusa in mice — animal studyView study →}. Isolated arbutin showed no toxicity in rodents or in cell tests ^{23Reference 23Taha et al. · 2012Gastroprotective activities of Turnera diffusa revisited: role of arbutin — animal studyView study →}. There are no formal human safety studies.

Blood sugar. Older reports describe a water-soluble blood-sugar-lowering action ^{34Reference 34Taylor · 2005The healing power of rainforest herbs: A guide to understanding and using herbal medicinals}, and the isolated compound teuhetenone A lowered glucose in normal and diabetic mice ^{24Reference 24Parra-Naranjo et al. · 2017Acute hypoglycemic and antidiabetic effect of teuhetenone A isolated from Turnera diffusa — animal studyView study →}. Damiana may therefore add to the effect of diabetes medicines.

Hormonal activity. The leaf flavonoids pinocembrin and acacetin inhibit aromatase, and several leaf compounds are estrogenic or bind estrogen receptors in laboratory tests ^{15,16Reference 15Zhao et al. · 2008In vitroAnti-aromatase activity of the constituents from damiana (Turnera diffusa) — in vitroView study →Reference 16Powers et al. · 2015A molecular docking study of phytochemical estrogen mimics from dietary herbal supplements — in silicoView study →}. This has not been shown with the whole herb in people, but it is a reason for care in hormone-sensitive conditions.

Cyanogenic glycosides. The leaves contain the cyanogenic glycoside tetraphyllin B ^{34Reference 34Taylor · 2005The healing power of rainforest herbs: A guide to understanding and using herbal medicinals}, and seven such compounds are known from the genus ^{3Reference 3Szewczyk et al. · 2014ReviewEthnobotany, phytochemistry, and bioactivity of the genus Turnera with a focus on damiana — reviewView study →}.

Long-term use. Damiana is traditionally not taken long term. The 28-day mouse study was reassuring ^{12Reference 12Ana María et al. · 2019AnimalNeurobehavioral and toxicological effects of an aqueous extract of Turnera diffusa in mice — animal studyView study →}.

Product quality. Sexual-enhancement supplements are sometimes adulterated with erectile-dysfunction drugs (PDE5 inhibitors). A 2026 screen of 20 damiana supplements found none ^{19Reference 19Jiménez-Amezcua et al. · 2026Analytical strategies for identifying PDE5 inhibitors in damiana (Turnera diffusa) productsView study →}.

Interactions. No clinical drug-interaction or CYP450 study has been done.