Passionflower

What Is Passionflower?

Passionflower is a climbing vine of the southeastern United States, valued as a gentle calming herb. Its leaves and stems (the aerial parts) are dried for teas, tinctures and standardized extracts, taken for anxiety, restlessness and poor sleep.

Passiflora incarnata, also called maypop, grows in open woods, prairies and disturbed ground from Texas and Kansas east to Florida and north to Virginia and Ohio ^{45Reference 45GoldmanH., & MacDougal, JView study →}. Native Americans gathered its fruit for thousands of years, and the leaf has long been taken as a sedative tea ^{32,45Reference 32Miroddi et al. · 2013Clinical trialPassiflora incarnata L.: ethnopharmacology, clinical application, safety and evaluation of clinical trials — reviewView study →Reference 45GoldmanH., & MacDougal, JView study →}.

The leaves carry flavonoids, chiefly vitexin and isovitexin, along with trace amounts of harmala alkaloids ^{32,38Reference 32Miroddi et al. · 2013Clinical trialPassiflora incarnata L.: ethnopharmacology, clinical application, safety and evaluation of clinical trials — reviewView study →Reference 38Rehwald et al. · 1995Trace analysis of harman alkaloids in Passiflora incarnata by reversed-phase high-performance liquid chromatography}. Small human trials have studied it for anxiety before surgery and dental work and for sleep, with generally positive but modest results ^{2,7,11Reference 2Movafegh et al. · 2008RCTPreoperative oral Passiflora incarnata reduces anxiety in ambulatory surgery patients: a double-blind, placebo-controlled study — randomised, placebo-controlledView study →Reference 7Miyasaka et al. · 2007Systematic reviewPassiflora for anxiety disorder — systematic review (Cochrane)View study →Reference 11Lee et al. · 2020RCTEffects of Passiflora incarnata Linnaeus on polysomnographic sleep parameters in subjects with insomnia disorder — randomised, placebo-controlledView study →}.

It is often confused with passion fruit (P. edulis), a tropical food crop in the same genus.

How Is Passionflower Used?

Passionflower is used as the dried aerial parts. In Europe it is sold as registered herbal medicines for mild stress and to aid sleep ^{14,43Reference 14da Fonseca et al. · 2020ReviewHerbal medicinal products from Passiflora for anxiety: an unexploited potential — reviewView study →Reference 43Brouns et al. · 2025Passionflower (Passiflora incarnata): quality of food supplements versus registered herbal medicinal products — analyticalView study →}. It is often combined with other calming herbs, such as valerian, hops, lemon balm and St John’s wort, in sleep and anxiety formulas ^{40Reference 40Ulmer et al. · 2004Passiflora: Passionflowers of the World}.

• Tea — 2–4 g of dried herb per cup, up to three times daily.
• Tincture (1:5) — 3–6 mL, up to three times daily.
• Liquid extract (1:2) — 15–40 mL per week.
• Standardized extracts — tablets and drops, dosed according to the product.

The Passionflowers

Passiflora holds about 550 species, most of them in tropical America ^{46Reference 46GoldmanH., & MacDougal, JView study →}. P. incarnata is the species used in Europe’s registered passionflower medicines and grown as a medicinal crop ^{40,43Reference 40Ulmer et al. · 2004Passiflora: Passionflowers of the WorldReference 43Brouns et al. · 2025Passionflower (Passiflora incarnata): quality of food supplements versus registered herbal medicinal products — analyticalView study →}. In an analysis of the European market, five of six passionflower food supplements failed identity or content testing, while all the registered medicines passed ^{43Reference 43Brouns et al. · 2025Passionflower (Passiflora incarnata): quality of food supplements versus registered herbal medicinal products — analyticalView study →}.

Several other species are used as medicines, mostly in Brazil and the tropics. In rodents, leaf extracts of P. alata and P. edulis both reduced anxious behaviour over the same dose range ^{42Reference 42Petry et al. · 2001AnimalComparative pharmacological study of hydroethanol extracts of Passiflora alata and Passiflora edulis leaves — animal modelView study →}. The species differ in the part used, and their flavonoid profiles can be told apart by mass spectrometry ^{44Reference 44McCullagh et al. · 2021Profiling of the known-unknown Passiflora variant complement by liquid chromatography-ion mobility-mass spectrometry — analyticalView study →}.

Other Medicinal Passionflowers

• Winged-stem passionflower (P. alata) — Brazil’s official passionflower, listed in its pharmacopoeia since 1929. The leaf is used as a calming and sedative herb.
• Passion fruit (P. edulis) — the fruit crop. Its leaf is used as a sedative, and its fruit peel and seeds have been studied separately.
• Stinking passionflower (P. foetida) — a tropical weed used for pain rather than for calm ^{23Reference 23Sasikala et al. · 2011AnimalAnalgesic and anti-inflammatory activities of Passiflora foetida L. — animal modelView study →}.
• Blue passionflower (P. caerulea) — a hardy ornamental grown in Europe.

Other Passifloras

Most of the rest of the genus is grown for fruit or as ornamentals.

• Giant granadilla (P. quadrangularis) — a tropical fruit crop with the largest fruit in the genus. In a comparison of three species, its stem extract had the highest phenolic content ^{25Reference 25Ramaiya et al. · 2014In vitroAssessment of total phenolic, antioxidant, and antibacterial activities of Passiflora species — in vitroView study →}. Its extract reduced activity in mice ^{41Reference 41Sakalem et al. · 2022AnimalBehavioral pharmacology of five uncommon Passiflora species indicates sedative and anxiolytic-like potential — animal modelView study →}.
• Red granadilla (P. coccinea) — reduced activity in mice and shortened the time they took to fall asleep ^{41Reference 41Sakalem et al. · 2022AnimalBehavioral pharmacology of five uncommon Passiflora species indicates sedative and anxiolytic-like potential — animal modelView study →}.
• P. sidaefolia — reduced anxious behaviour in mice about as well as P. incarnata, without affecting movement ^{41Reference 41Sakalem et al. · 2022AnimalBehavioral pharmacology of five uncommon Passiflora species indicates sedative and anxiolytic-like potential — animal modelView study →}.
• Sweet granadilla (P. ligularis), banana passionfruit (P. tripartita var. mollissima), water lemon (P. laurifolia) and sweet calabash (P. maliformis) — Latin American fruit crops. The leaf extract of P. maliformis had the highest phenolic content and antioxidant activity of the three species tested in one study ^{25Reference 25Ramaiya et al. · 2014In vitroAssessment of total phenolic, antioxidant, and antibacterial activities of Passiflora species — in vitroView study →}.
• P. bahiensis and P. vitifolia — tested alongside the sedative species and showed no calming effect in mice ^{41Reference 41Sakalem et al. · 2022AnimalBehavioral pharmacology of five uncommon Passiflora species indicates sedative and anxiolytic-like potential — animal modelView study →}.

Traditional Uses

Native American Medicine

Native Americans may have cultivated maypop, or at least gathered its edible fruit, for more than 3,000 years before European settlement ^{45Reference 45GoldmanH., & MacDougal, JView study →}.

The Cherokee used it for skin infections and earache, as a liver tonic, and for weaning babies. The Houma used it as a blood tonic ^{45Reference 45GoldmanH., & MacDougal, JView study →}.

North American & European Herbal Medicine

Nineteenth-century North American practice used the leaf infusion as a sedative for headache, nerve pain (neuralgia) and general pain ^{39Reference 39Taylor · 2005The Healing Power of Rainforest Herbs}.

In North America it has been taken as a sedative tea, and in folk practice for diarrhoea, menstrual pain, neuralgia, burns, haemorrhoids and insomnia ^{32Reference 32Miroddi et al. · 2013Clinical trialPassiflora incarnata L.: ethnopharmacology, clinical application, safety and evaluation of clinical trials — reviewView study →}. In Europe it has long been used for insomnia and anxiety ^{32Reference 32Miroddi et al. · 2013Clinical trialPassiflora incarnata L.: ethnopharmacology, clinical application, safety and evaluation of clinical trials — reviewView study →}.

Spanish explorers were the first Europeans to meet Passiflora, and some read the flower as a symbol of the Crucifixion: the three styles as the nails and the corona as the crown of thorns. This led to its cultivation in Europe in the early seventeenth century, and P. incarnata was probably the first species grown there ^{46Reference 46GoldmanH., & MacDougal, JView study →}.

Polish & Turkish Folk Medicine

In Poland the herb was used for hysteria and nervous exhaustion (neurasthenia) ^{32Reference 32Miroddi et al. · 2013Clinical trialPassiflora incarnata L.: ethnopharmacology, clinical application, safety and evaluation of clinical trials — reviewView study →}.

In Turkey it was used for menstrual pain, epilepsy, insomnia, nervous complaints and neuralgia ^{32Reference 32Miroddi et al. · 2013Clinical trialPassiflora incarnata L.: ethnopharmacology, clinical application, safety and evaluation of clinical trials — reviewView study →}.

Brazilian Folk Medicine

In Brazil P. incarnata has been used for pain, spasm, asthma and worms, and as a sedative ^{32Reference 32Miroddi et al. · 2013Clinical trialPassiflora incarnata L.: ethnopharmacology, clinical application, safety and evaluation of clinical trials — reviewView study →}.

Iraqi & Indian Folk Medicine

In Iraq it has been used as a sedative and narcotic, and in India to treat opiate dependence ^{32Reference 32Miroddi et al. · 2013Clinical trialPassiflora incarnata L.: ethnopharmacology, clinical application, safety and evaluation of clinical trials — reviewView study →}.

Indications

• Anxiety, including before surgery and dental work [aerial parts; European and North American herbal medicine] ⚠Caution: A Cochrane review found too few trials to draw conclusions, and a 2022 network meta-analysis did not find a significant reduction in anxiety scores ^7,8.
• Insomnia and poor sleep quality [aerial parts, as tea or extract]
• Nervous tension and restlessness [aerial parts]
• Opiate withdrawal, alongside standard treatment [aerial-part extract; Indian folk use]
• ADHD in children [aerial-part extract]
• Epilepsy and seizures [aerial parts; Turkish folk use]
• Headache and nerve pain [leaf infusion; North American herbal medicine]
• Menstrual pain [aerial parts; North American and Turkish folk use]
• Muscle spasm and mild high blood pressure [aerial parts] ⚠Caution: The harmala alkaloids linked to this use occur only in trace amounts in P. incarnata, and the effect has been shown only in isolated animal tissue ^22,38.
• Asthma [aerial parts; Brazilian folk use]
• Haemorrhoids and burns [aerial parts; North American folk use]
• Skin infections and earache [Cherokee use]

Botany

Passionflower is a fast-growing perennial vine in the Passifloraceae that climbs by tendrils ^{46,47Reference 46GoldmanH., & MacDougal, JView study →Reference 47North Carolina State Extension (n.d.)Passiflora incarnata (Passionflower, Maypop) — species description, native range and growing conditions — plant databaseView study →}. In cold-winter climates its stems die back to the ground each year ^{45,47Reference 45GoldmanH., & MacDougal, JView study →Reference 47North Carolina State Extension (n.d.)Passiflora incarnata (Passionflower, Maypop) — species description, native range and growing conditions — plant databaseView study →}.

It spreads by suckers from deep, far-reaching roots, and can cover large areas in well-drained soil ^{45Reference 45GoldmanH., & MacDougal, JView study →}.

The leaves are 4–12 cm long, deeply three-lobed (sometimes five-lobed) and toothed along the edges. The leaf stalk carries a pair of glands ^{45,47Reference 45GoldmanH., & MacDougal, JView study →Reference 47North Carolina State Extension (n.d.)Passiflora incarnata (Passionflower, Maypop) — species description, native range and growing conditions — plant databaseView study →}.

The flowers are fragrant and 2.5–7.5 cm across. They have white to lavender petals and sepals around a crown of fringed, purple-pink filaments ^{47Reference 47North Carolina State Extension (n.d.)Passiflora incarnata (Passionflower, Maypop) — species description, native range and growing conditions — plant databaseView study →}. Carpenter bees are the main pollinators ^{46Reference 46GoldmanH., & MacDougal, JView study →}.

The fruit is a fleshy, egg-shaped berry, the maypop, which turns yellowish when ripe ^{47Reference 47North Carolina State Extension (n.d.)Passiflora incarnata (Passionflower, Maypop) — species description, native range and growing conditions — plant databaseView study →}. The whole genus contains cyanide-releasing compounds, and unripe Passiflora fruit is probably poisonous ^{46Reference 46GoldmanH., & MacDougal, JView study →}.

Passion fruit (P. edulis) is a close relative. It has larger stipules (at least 10 mm) and larger, leaf-like bracts beneath the flower ^{45Reference 45GoldmanH., & MacDougal, JView study →}.

Distribution

Passionflower is native to the southeastern and south-central United States and Bermuda ^{45,47Reference 45GoldmanH., & MacDougal, JView study →Reference 47North Carolina State Extension (n.d.)Passiflora incarnata (Passionflower, Maypop) — species description, native range and growing conditions — plant databaseView study →}. Its native range probably reaches no farther north than southern Illinois and Ohio, central Virginia and West Virginia, though it is very cold-hardy and turns up further north ^{45Reference 45GoldmanH., & MacDougal, JView study →}.

It grows in open woodland, savanna, prairie, dunes, cultivated ground and disturbed places, often in poor, dry to moist soil, from sea level to about 1,000 m ^{45Reference 45GoldmanH., & MacDougal, JView study →}. Its range has probably spread with the clearing of land. It can be a weed of cropland, yet it is rare in parts of its range, such as Indiana and Ohio ^{45Reference 45GoldmanH., & MacDougal, JView study →}.

P. incarnata is grown commercially as a medicinal crop in the United States, Brazil, India and elsewhere ^{40Reference 40Ulmer et al. · 2004Passiflora: Passionflowers of the World}.

Growing Conditions

Cultivation snapshot for Passionflower

SunFull sun to part shadeWaterMedium; drought-tolerant once establishedLifeperennialZoneUSDA 5–9

SoilAverage, well-drained soils; roots can rot in wet, poorly drained ground.

• Spreads by root suckers, so give it room or contain it.

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Phytochemistry

The dried aerial parts contain about 2.5% total flavonoids, mainly C-glycosides: vitexin, isovitexin, orientin, isoorientin and schaftoside ^{32Reference 32Miroddi et al. · 2013Clinical trialPassiflora incarnata L.: ethnopharmacology, clinical application, safety and evaluation of clinical trials — reviewView study →}. These serve as the pharmacopoeial markers.

The herb also contains trace β-carboline (harmala) alkaloids, including harman, harmine, harmaline and tetrahydroharmine. Harman makes up roughly 0.005–0.012% of the dry herb ^{38Reference 38Rehwald et al. · 1995Trace analysis of harman alkaloids in Passiflora incarnata by reversed-phase high-performance liquid chromatography}. The γ-pyrone maltol has been linked to the herb’s sedative effect ^{39Reference 39Taylor · 2005The Healing Power of Rainforest Herbs}.

The flavonoids chrysin and apigenin have shown anxiolytic-type effects in animals ^{27,28Reference 27Zanoli et al. · 2000AnimalBehavioural characterisation of the flavonoids apigenin and chrysin — animal modelView study →Reference 28Brown et al. · 2007AnimalEvaluation of the anxiolytic effects of chrysin, a Passiflora incarnata extract, in the laboratory rat — animal modelView study →}. A characterized whole extract reduced anxious behaviour in mice through the GABA system ^{20Reference 20Grundmann et al. · 2008AnimalAnxiolytic activity of a phytochemically characterized Passiflora incarnata extract is mediated via the GABAergic system — animal modelView study →}.

Harmala alkaloids occur at far higher levels in ayahuasca vine and Syrian rue than in passionflower.

Constituent Summary

Percent of dry herb; levels vary with plant part and growing conditions.

Other Constituents

P. incarnata also contains further flavonoids (apigenin, kaempferol, quercetin, vicenin, lucenin, saponarin), triterpene saponins (cyclopassiflosides), the coumarin scopoletin, phytosterols (β-sitosterol, stigmasterol), fatty acids (linoleic, linolenic, palmitic, oleic and myristic), maltol and trace serotonin ^{32,39Reference 32Miroddi et al. · 2013Clinical trialPassiflora incarnata L.: ethnopharmacology, clinical application, safety and evaluation of clinical trials — reviewView study →Reference 39Taylor · 2005The Healing Power of Rainforest Herbs}.

It also contains cyanogenic glycosides such as gynocardin, which serve in plant defence and decline as the leaves age ^{32,39Reference 32Miroddi et al. · 2013Clinical trialPassiflora incarnata L.: ethnopharmacology, clinical application, safety and evaluation of clinical trials — reviewView study →Reference 39Taylor · 2005The Healing Power of Rainforest Herbs}. The extract contains a substantial amount of GABA itself ^{18Reference 18Elsas et al. · 2010In vitroPassiflora incarnata L. (Passionflower) extracts elicit GABA currents in hippocampal neurons in vitro, and show anxiogenic and anticonvulsant effects in vivo — in vitro / animal modelView study →}.

Pharmacology & Research

P. incarnata aerial parts carry a European Medicines Agency herbal monograph and appear in several pharmacopoeias for mild stress and sleep disturbance ^{14Reference 14da Fonseca et al. · 2020ReviewHerbal medicinal products from Passiflora for anxiety: an unexploited potential — reviewView study →}. The human trials centre on anxiety, especially before surgery and dental procedures, and on sleep ^{1,2,3,4,5,6,10,11,12Reference 1Akhondzadeh et al. · 2001RCTPassionflower in the treatment of generalized anxiety: a pilot double-blind randomized controlled trial with oxazepam — randomisedView study →Reference 2Movafegh et al. · 2008RCTPreoperative oral Passiflora incarnata reduces anxiety in ambulatory surgery patients: a double-blind, placebo-controlled study — randomised, placebo-controlledView study →Reference 3Aslanargun et al. · 2012RCTPassiflora incarnata Linneaus as an anxiolytic before spinal anesthesia — randomised, placebo-controlledView study →Reference 4Dantas et al. · 2017RCTEffects of passiflora incarnata and midazolam for control of anxiety in patients undergoing dental extraction — randomised, double-blind crossoverView study →Reference 5Lima Neto et al. · 2025RCTEffects of Passiflora incarnata on salivary biomarkers and anxiety in patients undergoing third molar extraction surgery — randomised, placebo-controlledView study →Reference 6Christoffoli et al. · 2021RCTAssessment of Passiflora incarnata L for conscious sedation during extraction of mandibular third molars — randomised, double-blind crossoverView study →Reference 10Ngan et al. · 2011RCTA double-blind, placebo-controlled investigation of the effects of Passiflora incarnata (passionflower) herbal tea on subjective sleep quality — randomised, placebo-controlledView study →Reference 11Lee et al. · 2020RCTEffects of Passiflora incarnata Linnaeus on polysomnographic sleep parameters in subjects with insomnia disorder — randomised, placebo-controlledView study →Reference 12Harit et al. · 2024RCTRandomized, double-blind, placebo-controlled clinical study of Passiflora incarnata in participants with stress and sleep problems — randomised, placebo-controlledView study →}.

Systematic reviews describe these trials as small, with extracts that are often poorly described ^{7,13,32Reference 7Miyasaka et al. · 2007Systematic reviewPassiflora for anxiety disorder — systematic review (Cochrane)View study →Reference 13Janda et al. · 2020Systematic reviewPassiflora incarnata in neuropsychiatric disorders — a systematic reviewView study →Reference 32Miroddi et al. · 2013Clinical trialPassiflora incarnata L.: ethnopharmacology, clinical application, safety and evaluation of clinical trials — reviewView study →}. Much of the rest of the pharmacology comes from animal and cell studies, from other Passiflora species, or from the isolated flavonoid chrysin rather than the whole herb ^{23,25,26Reference 23Sasikala et al. · 2011AnimalAnalgesic and anti-inflammatory activities of Passiflora foetida L. — animal modelView study →Reference 25Ramaiya et al. · 2014In vitroAssessment of total phenolic, antioxidant, and antibacterial activities of Passiflora species — in vitroView study →Reference 26Kasala et al. · 2015In vitroChemopreventive and therapeutic potential of chrysin in cancer: mechanistic perspectives — review (in vitro / animal)View study →}.

1. Anxiety

A pilot double-blind RCT in 36 people with generalized anxiety disorder found a P. incarnata extract (45 drops/day) as effective as oxazepam 30 mg/day over four weeks. Oxazepam acted faster, but caused more impairment of job performance ^{1Reference 1Akhondzadeh et al. · 2001RCTPassionflower in the treatment of generalized anxiety: a pilot double-blind randomized controlled trial with oxazepam — randomisedView study →}.

Most of the evidence concerns anxiety before a procedure. In 60 outpatients, 500 mg of oral P. incarnata 90 minutes before surgery lowered anxiety without causing sedation or slowing recovery ^{2Reference 2Movafegh et al. · 2008RCTPreoperative oral Passiflora incarnata reduces anxiety in ambulatory surgery patients: a double-blind, placebo-controlled study — randomised, placebo-controlledView study →}. A second trial of 60 patients found that it blunted the rise in anxiety before spinal anaesthesia, without changing psychomotor function or blood pressure ^{3Reference 3Aslanargun et al. · 2012RCTPassiflora incarnata Linneaus as an anxiolytic before spinal anesthesia — randomised, placebo-controlledView study →}.

In dental surgery, 260 mg of P. incarnata had an anxiolytic effect similar to 15 mg of midazolam in a 40-person crossover trial, with little effect on memory ^{4Reference 4Dantas et al. · 2017RCTEffects of passiflora incarnata and midazolam for control of anxiety in patients undergoing dental extraction — randomised, double-blind crossoverView study →}. A 20-person crossover trial also found it comparable to midazolam, with less drowsiness and dizziness ^{6Reference 6Christoffoli et al. · 2021RCTAssessment of Passiflora incarnata L for conscious sedation during extraction of mandibular third molars — randomised, double-blind crossoverView study →}. A 2025 trial of 30 patients found no difference in anxiety scores between passionflower, midazolam and placebo, though salivary cortisol after surgery was lower with passionflower and midazolam than with placebo ^{5Reference 5Lima Neto et al. · 2025RCTEffects of Passiflora incarnata on salivary biomarkers and anxiety in patients undergoing third molar extraction surgery — randomised, placebo-controlledView study →}.

A 2007 Cochrane review found the trials too few and too small to draw conclusions ^{7Reference 7Miyasaka et al. · 2007Systematic reviewPassiflora for anxiety disorder — systematic review (Cochrane)View study →}. In a 2022 Bayesian network meta-analysis, passionflower did not significantly reduce Hamilton anxiety scores in the summary network, though the authors judged it worth further study ^{8Reference 8Zhang et al. · 2022Meta-analysisMedicinal herbs for the treatment of anxiety: a systematic review and network meta-analysis — systematic reviewView study →}.

The effect has been linked to GABA_A signalling in cell studies ^{18,19Reference 18Elsas et al. · 2010In vitroPassiflora incarnata L. (Passionflower) extracts elicit GABA currents in hippocampal neurons in vitro, and show anxiogenic and anticonvulsant effects in vivo — in vitro / animal modelView study →Reference 19Appel et al. · 2011In vitroModulation of the γ-aminobutyric acid (GABA) system by Passiflora incarnata L. — in vitroView study →}.

Gap: Trials are small, mostly single-centre, and use different proprietary extracts. No large, standardized-dose RCT has tested it for chronic generalized anxiety.

2. Sleep & Insomnia

Three small human RCTs report a short-term sleep benefit. A low-dose P. incarnata tea, one cup nightly for a week, improved subjective sleep quality versus placebo in 41 healthy adults with mild sleep fluctuations ^{10Reference 10Ngan et al. · 2011RCTA double-blind, placebo-controlled investigation of the effects of Passiflora incarnata (passionflower) herbal tea on subjective sleep quality — randomised, placebo-controlledView study →}.

A double-blind trial in 110 adults with insomnia disorder found that an extract increased total sleep time on polysomnography after two weeks. Sleep efficiency and waking after sleep onset improved in the passionflower group, but not significantly more than with placebo ^{11Reference 11Lee et al. · 2020RCTEffects of Passiflora incarnata Linnaeus on polysomnographic sleep parameters in subjects with insomnia disorder — randomised, placebo-controlledView study →}.

A 2024 placebo-controlled trial in 65 adults with stress and sleep problems found that a standardized extract taken for 30 days reduced perceived stress and increased total sleep time, with no adverse effects ^{12Reference 12Harit et al. · 2024RCTRandomized, double-blind, placebo-controlled clinical study of Passiflora incarnata in participants with stress and sleep problems — randomised, placebo-controlledView study →}.

Effects are modest and short-term, and the trials used different preparations and doses.

3. Substance-Withdrawal Adjunct

A double-blind RCT in 65 people undergoing outpatient opiate detoxification compared clonidine plus P. incarnata extract (60 drops daily) with clonidine plus placebo for 14 days. Both groups did equally well on physical withdrawal symptoms, but the passionflower group did significantly better on mental symptoms ^{15Reference 15Akhondzadeh et al. · 2001RCTPassionflower in the treatment of opiates withdrawal: a double-blind randomized controlled trial — randomisedView study →}.

In mice, a commercial P. incarnata extract reduced naloxone-induced withdrawal jumping in morphine-dependent animals without reducing movement ^{16Reference 16Dos Reis Izolan et al. · 2021AnimalSintocalmy, a Passiflora incarnata based herbal, attenuates morphine withdrawal in mice — animal modelView study →}.

There is also a registered but unpublished trial in benzodiazepine withdrawal. The one human trial combined the herb with clonidine, so passionflower’s effect on its own has not been tested.

4. Anticonvulsant

In mice, an injected P. incarnata hydroalcoholic extract delayed the onset of chemically induced seizures, shortened them and prevented deaths. The effect was blocked by flumazenil and naloxone, pointing to GABA and opioid involvement ^{17Reference 17Nassiri-Asl et al. · 2007AnimalAnticonvulsant effects of aerial parts of Passiflora incarnata extract in mice: involvement of benzodiazepine and opioid receptors — animal modelView study →}.

In a second study, extracts elicited GABA currents in hippocampal neurons, and two of five extracts were anticonvulsant in mice. All five extracts made the mice more anxious rather than less in a maze test, and the results varied with the extraction method ^{18Reference 18Elsas et al. · 2010In vitroPassiflora incarnata L. (Passionflower) extracts elicit GABA currents in hippocampal neurons in vitro, and show anxiogenic and anticonvulsant effects in vivo — in vitro / animal modelView study →}.

A registered trial in partial epilepsy was withdrawn before completion. There is no human anticonvulsant data.

5. Antioxidant

Leaf and stem extracts of P. quadrangularis, P. maliformis and P. edulis showed antioxidant activity in laboratory assays that tracked their phenolic content. P. maliformis leaf and P. quadrangularis stem extracts were the strongest ^{25Reference 25Ramaiya et al. · 2014In vitroAssessment of total phenolic, antioxidant, and antibacterial activities of Passiflora species — in vitroView study →}.

P. incarnata was not included in that study, and there is no human data on antioxidant status.

6. Antispasmodic & Hypotensive

The traditional muscle-relaxant and mild blood-pressure-lowering reputation is attributed to the harmala (β-carboline) alkaloids. In rabbit aorta and guinea-pig intestine, harmaline and related alkaloids relaxed smooth muscle by blocking calcium channels, with half-maximal effects at around 50–70 µM ^{22Reference 22Karaki et al. · 1986In vitroInhibition of calcium channels by harmaline and other harmala alkaloids in vascular and intestinal smooth muscles — in vitroView study →}.

Harmane and harmine occur only in trace amounts in P. incarnata, roughly 0.005–0.012% of the dry herb ^{38Reference 38Rehwald et al. · 1995Trace analysis of harman alkaloids in Passiflora incarnata by reversed-phase high-performance liquid chromatography}.

Gap: The mechanism has been shown only in isolated animal tissue, at concentrations far above what the herb’s trace alkaloids would deliver. There is no human cardiovascular trial.

7. Antidepressant

The antidepressant findings come from the isolated flavonoid chrysin. In mice under chronic mild stress, chrysin reversed depression-like behaviour, normalized corticosterone and raised BDNF and NGF in the hippocampus and prefrontal cortex, with effects comparable to fluoxetine ^{29Reference 29Filho et al. · 2015AnimalChronic unpredictable mild stress decreases BDNF and NGF levels and Na⁺,K⁺-ATPase activity in the hippocampus and prefrontal cortex of mice: antidepressant effect of chrysin — animal modelView study →}.

Chrysin also occurs in propolis and honey, and the doses used far exceed what the herb provides.

Gap: No study has tested P. incarnata itself for depression.

8. Antimicrobial

“Passicol”, a substance obtained from Passiflora species, was active in vitro against a wide range of moulds, yeasts and bacteria, both Gram-positive and Gram-negative. It was non-toxic to mice and rabbits ^{24Reference 24Nicolls et al. · 1973In vitroPassicol, an antibacterial and antifungal agent produced by Passiflora plant species — in vitroView study →}.

Extracts of P. edulis, P. maliformis and P. quadrangularis inhibited Gram-positive but not Gram-negative bacteria ^{25Reference 25Ramaiya et al. · 2014In vitroAssessment of total phenolic, antioxidant, and antibacterial activities of Passiflora species — in vitroView study →}.

These are laboratory findings, largely from species other than P. incarnata, with no clinical data.

9. Analgesic & Anti-Inflammatory

The analgesic and anti-inflammatory data come from P. foetida, a different species. Its ethanol leaf extract raised the pain threshold in mice at 200 mg/kg and reduced paw swelling in rats at 100 mg/kg ^{23Reference 23Sasikala et al. · 2011AnimalAnalgesic and anti-inflammatory activities of Passiflora foetida L. — animal modelView study →}.

The Cherokee used P. incarnata on the skin for infections, but it has not been tested for pain or inflammation ^{45Reference 45GoldmanH., & MacDougal, JView study →}.

10. Antitussive

A 2002 mouse study found that a methanol leaf extract of P. incarnata (100 and 200 mg/kg by mouth) suppressed cough by 39% and 65%, comparable to codeine ^{21Reference 21Dhawan et al. · 2002AnimalAntitussive activity of the methanol extract of Passiflora incarnata leaves — animal modelView study →}. It has not been repeated or tested in humans.

11. Neuroprotective

The neuroprotective findings come from isolated constituents. Chrysin reduced brain damage and neurological deficits in a mouse model of stroke through anti-inflammatory and antioxidant effects ^{30Reference 30Yao et al. · 2014AnimalChrysin protects against focal cerebral ischemia/reperfusion injury in mice through attenuation of oxidative stress and inflammation — animal modelView study →}, and maltol protected rat retinal nerve cells against oxidative stress ^{31Reference 31Song et al. · 2015In vitroThe neuroprotective effect of maltol against oxidative stress on rat retinal neuronal cells — in vitro / animal modelView study →}.

Both are single-compound studies at high doses in acute injury models. There is no whole-herb data.

12. Anticancer (Chemoprotective)

All of the anticancer data concern isolated chrysin, which slows the growth of many cancer cell lines and some rodent tumours ^{26Reference 26Kasala et al. · 2015In vitroChemopreventive and therapeutic potential of chrysin in cancer: mechanistic perspectives — review (in vitro / animal)View study →}.

None of this work used P. incarnata extract, and there is no human data.

Gap: Entirely isolated-chrysin, in vitro and in rodents.

Mechanisms

Whole passionflower extract produces GABA_A currents in brain cells, in part because the extract itself contains GABA ^{18,19Reference 18Elsas et al. · 2010In vitroPassiflora incarnata L. (Passionflower) extracts elicit GABA currents in hippocampal neurons in vitro, and show anxiogenic and anticonvulsant effects in vivo — in vitro / animal modelView study →Reference 19Appel et al. · 2011In vitroModulation of the γ-aminobutyric acid (GABA) system by Passiflora incarnata L. — in vitroView study →}. The flavonoids chrysin and apigenin have been studied for anxiolytic effects in animals, and a characterized extract acts through the GABA system in mice ^{20,27,28Reference 20Grundmann et al. · 2008AnimalAnxiolytic activity of a phytochemically characterized Passiflora incarnata extract is mediated via the GABAergic system — animal modelView study →Reference 27Zanoli et al. · 2000AnimalBehavioural characterisation of the flavonoids apigenin and chrysin — animal modelView study →Reference 28Brown et al. · 2007AnimalEvaluation of the anxiolytic effects of chrysin, a Passiflora incarnata extract, in the laboratory rat — animal modelView study →}.

The harmala alkaloids block calcium channels in smooth muscle, but they are present in passionflower only in trace amounts ^{22,38Reference 22Karaki et al. · 1986In vitroInhibition of calcium channels by harmaline and other harmala alkaloids in vascular and intestinal smooth muscles — in vitroView study →Reference 38Rehwald et al. · 1995Trace analysis of harman alkaloids in Passiflora incarnata by reversed-phase high-performance liquid chromatography}. The antidepressant, neuroprotective and anticancer mechanisms come from isolated chrysin.

Clinical Trials

The registered and published human trials are small and concentrate on anxiety (including before surgery and dental work) and sleep. Of 13 trials on ClinicalTrials.gov, 6 are completed, 2 were withdrawn (climacteric syndrome; partial epilepsy) and 5 have an unknown status.

Last checked: July 2026.

Dosage

In trials, passionflower is given mostly as proprietary extracts dosed by product weight. These are research doses, not recommendations.

Traditional Dosage

These are the EU traditional-use doses for adults and adolescents over 12, for mild stress and to aid sleep ^{48Reference 48European Medicines Agency · 2014ReviewCommunity herbal monograph on Passiflora incarnata L., herba, EMA/HMPC/669740/2013 — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-community-herbal-monograph-passiflora-incarnata-l-herba_en.pdfView study →}.

Safety & Pregnancy

Passionflower is generally well tolerated. Its main caution is that it adds to the effect of sedative drugs and alcohol.

Full Safety & Interactions Detail

General tolerance. Passionflower is generally well tolerated at customary doses, and reviewers describe a good safety profile ^{32Reference 32Miroddi et al. · 2013Clinical trialPassiflora incarnata L.: ethnopharmacology, clinical application, safety and evaluation of clinical trials — reviewView study →}. Reported side effects are usually mild: drowsiness, dizziness and nausea. P. incarnata is classified as generally recognized as safe (GRAS) for food use in the United States ^{32Reference 32Miroddi et al. · 2013Clinical trialPassiflora incarnata L.: ethnopharmacology, clinical application, safety and evaluation of clinical trials — reviewView study →}.

Sedatives. It may add to the effect of benzodiazepines, barbiturates and other sedatives. A man taking lorazepam who also took valerian and passionflower developed trembling hands, dizziness, throbbing and muscle fatigue, which was attributed to an additive effect ^{37Reference 37Carrasco et al. · 2009Case reportInteractions of Valeriana officinalis L. and Passiflora incarnata L. in a patient treated with lorazepam — case reportView study →}.

Heart rhythm. A 34-year-old woman developed severe nausea, vomiting, drowsiness, QTc prolongation and episodes of non-sustained ventricular tachycardia after taking passionflower at therapeutic doses, and needed hospital monitoring ^{36Reference 36Fisher et al. · 2000Case reportToxicity of Passiflora incarnata L. — case reportView study →}.

Drug metabolism. In a laboratory study, a passionflower infusion raised the expression of the liver enzyme CYP3A4 in human liver cells but did not affect P-glycoprotein. No study has measured an effect on drug levels in people ^{49Reference 49Mazzari et al. · 2022In vitroIn vitro effects of European and Latin-American medicinal plants in CYP3A4 gene expression, glutathione levels, and P-glycoprotein activityView study →}.

Everyday use. Because it is sedating, avoid combining it with alcohol or driving until you know how it affects you, and stop it before surgery unless supervised.

References

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2. Movafegh, A., Alizadeh, R., Hajimohamadi, F., et al. (2008). Preoperative oral Passiflora incarnata reduces anxiety in ambulatory surgery patients: a double-blind, placebo-controlled study — randomised, placebo-controlled. Anesth Analg. https://pubmed.ncbi.nlm.nih.gov/18499602/
3. Aslanargun, P., Cuvas, O., Dikmen, B., et al. (2012). Passiflora incarnata Linneaus as an anxiolytic before spinal anesthesia — randomised, placebo-controlled. J Anesth. https://pubmed.ncbi.nlm.nih.gov/22048283/
4. Dantas, L. P., de Oliveira-Ribeiro, A., et al. (2017). Effects of passiflora incarnata and midazolam for control of anxiety in patients undergoing dental extraction — randomised, double-blind crossover. Med Oral Patol Oral Cir Bucal. https://pubmed.ncbi.nlm.nih.gov/27918731/
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