Passionflower (Passiflora incarnata) has a surprisingly long history as a medicinal plant. When Spanish explorers arrived in the Americas in the 16th century, they found indigenous peoples already using it for sleep troubles and anxiety. The name itself comes from missionaries who thought the flower’s structure symbolised the Passion of Christ, with its corona representing the crown of thorns.

Today, passionflower supplements and teas line pharmacy shelves throughout Europe and North America. But does the research support all these traditional uses? Here’s what we know so far.

What is passionflower?

The passionflower family (Passifloraceae) contains roughly 500 species, but Passiflora incarnata is the one primarily used in herbal medicine. It’s a climbing vine native to the southeastern United States, though you’ll now find it growing across tropical and subtropical regions worldwide.

You might recognise a close relative: passion fruit (Passiflora edulis) comes from the same family and is popular in tropical drinks and desserts.

The above-ground parts of the plant, including leaves, stems, and flowers, contain the active compounds. These include flavonoids like chrysin and apigenin, along with alkaloids and other phytochemicals that researchers believe are responsible for the calming effects [1].

Passionflower preparations come in various forms: dried herb for tea, liquid extracts, tinctures, and standardised capsules. The European Medicines Agency has approved it as a traditional herbal medicine for temporary relief of mild anxiety and sleep difficulties, though they note the evidence comes mainly from long-standing use rather than clinical trials [2].

What are the proven benefits of passionflower?

1. May help with generalised anxiety disorder

Generalised anxiety disorder involves persistent, excessive worry that interferes with daily life. People with this condition often know their concerns are disproportionate to actual threats, yet struggle to control them. The worry tends to show up physically too: restlessness, fatigue, muscle tension, difficulty concentrating, and sleep problems are common.

One double-blind trial from 2001 compared passionflower extract to oxazepam (a benzodiazepine drug) in 36 people with generalised anxiety disorder over four weeks. Both treatments reduced anxiety scores by similar amounts. The interesting difference was in side effects: the oxazepam group reported significantly more impairment in job performance, while the passionflower group tolerated treatment better [3].

That’s a promising finding, though I should be clear about the limitations. Thirty-six participants is a small sample. The study lasted only four weeks. And we don’t have good data on whether passionflower remains effective with longer use or how it compares to other treatments like cognitive behavioural therapy.

2. May improve sleep quality

Sleep problems affect far more people than most realise. Estimates suggest that between 50 and 70 million adults in the United States have chronic sleep or wakefulness disorders, with women affected more often than men [4].

A 2011 study looked at passionflower tea in 41 people who reported mild sleep difficulties. Participants drank a cup of tea containing 2 grams of dried passionflower or a placebo tea for one week each, with a week’s break in between. Sleep quality improved modestly when drinking the passionflower tea compared to placebo [5].

The effect was real but not dramatic. Sleep diaries showed better subjective sleep quality, though polysomnography (objective sleep measurement) didn’t show significant differences. This suggests passionflower might help you feel like you slept better without necessarily changing sleep architecture.

If you’re dealing with nocturia (waking frequently to urinate at night), passionflower alone probably won’t solve the underlying problem. But reducing anxiety before bed could theoretically help with sleep onset in some cases.

3. Can reduce preoperative anxiety

Anyone who’s faced surgery knows the anxiety that comes with it. Studies suggest between 60 and 80 percent of surgical patients experience significant preoperative anxiety, which can complicate anaesthesia, increase postoperative pain, and slow recovery.

A double-blind study from 2008 gave 60 patients undergoing outpatient surgery either passionflower extract or placebo 90 minutes before their procedure. Anxiety scores dropped significantly more in the passionflower group. However, the treatment didn’t affect psychomotor function or recovery time, and sedation levels were similar between groups [6].

This is actually encouraging from a safety standpoint. The passionflower reduced subjective anxiety without causing excessive sedation or impairing cognitive function, which are concerns with some prescription anxiolytics.

4. May support opioid withdrawal

Opioid addiction affects millions of people worldwide. Withdrawal symptoms, which include anxiety, irritability, insomnia, muscle aches, nausea, and intense cravings, make quitting extraordinarily difficult.

A 2001 trial compared two approaches in 65 people addicted to opioids: clonidine (a medication commonly used in withdrawal treatment) combined with either passionflower extract or placebo. Both groups improved in terms of physical withdrawal symptoms. But here’s where it gets interesting: the passionflower group showed significantly better improvement in psychological symptoms like anxiety and restlessness [7].

The researchers suggested passionflower could be a useful add-on treatment during opioid detoxification. It won’t replace medical treatment for addiction, but it might help manage some of the psychological distress that makes relapse so common.

5. May ease menopausal symptoms

The menopausal transition brings hormonal fluctuations that can cause hot flashes, mood changes, sleep disturbances, irritability, and other symptoms. Many women seek natural alternatives to hormone replacement therapy.

A clinical study followed 59 women with menopausal symptoms for six weeks. Both passionflower extract and St. John’s wort improved symptoms, particularly hot flashes, insomnia, depression, anger, and headaches [8].

Again, small sample size and short duration limit what we can conclude. But for women looking to try natural approaches before medication, passionflower is at least worth discussing with a healthcare provider.

How does passionflower work?

The mechanism isn’t fully understood, but researchers have some theories. Passionflower appears to increase levels of gamma-aminobutyric acid (GABA) in the brain, a neurotransmitter that reduces neuronal excitability. This is similar to how benzodiazepine medications work, though passionflower seems to act through different pathways and with less potency [9].

The flavonoids in passionflower, particularly chrysin, may bind to benzodiazepine receptors and enhance GABA activity. Other compounds might contribute to anti-inflammatory and antioxidant effects. If you’re interested in GABA-related supplements, you might also want to read about GABA supplements or L-theanine.

Are there side effects?

For most people taking appropriate doses short-term, passionflower appears well-tolerated. Reported side effects in studies have been mild and include:

Drowsiness or sedation
Dizziness
Confusion (rare, usually at high doses)
Nausea
Rapid heartbeat (uncommon)
Impaired coordination

One case report described an individual who developed altered consciousness and uncoordinated movements after taking passionflower, though this appeared to resolve after stopping the supplement [10]. Such reactions seem rare at standard doses.

The sedative effect is worth noting if you’re driving or operating machinery. Starting with a lower dose and taking it in the evening initially makes sense.

Safety precautions and contraindications

1. Pregnancy

Pregnant women should avoid passionflower. Some compounds in the plant may stimulate uterine contractions. Animal studies have raised concerns about potential harm to the developing foetus. Until we have better safety data, it’s not worth the risk.

2. Breastfeeding and children

We simply don’t have adequate safety information for nursing mothers or children. Most herbalists and regulatory bodies recommend avoiding passionflower in these populations.

3. Surgery

If you have scheduled surgery, stop taking passionflower at least two weeks beforehand. It could potentially interact with anaesthesia or affect bleeding. Inform your anaesthesiologist about any supplements you’ve been taking.

4. Interactions with sedative medications

Passionflower may enhance the effects of drugs that cause drowsiness. This includes:

Benzodiazepines (diazepam, lorazepam, clonazepam)
Barbiturates (phenobarbital, secobarbital)
Sleep medications (zolpidem, zopiclone)
Antihistamines
Some antidepressants
Alcohol

Combining passionflower with these substances could cause excessive sedation. If you take any prescription sedatives, speak with your doctor before adding passionflower.

What’s the recommended dosage?

There’s no officially established dose for passionflower. Clinical trials have used varying amounts, and optimal dosing likely depends on the specific preparation and individual factors.

Based on available research and traditional use, typical doses include:

For anxiety:

400-500 mg of dried extract capsules twice daily
45 drops of liquid extract daily
2-4 grams of dried herb as tea

For sleep:

1-2 cups of passionflower tea before bed
300-450 mg of extract 30-60 minutes before sleep

Start with lower doses and increase gradually if needed. Effects may take a few days to become noticeable.

If passionflower alone doesn’t provide enough relief, some people combine it with other calming herbs. Valerian is commonly paired with passionflower for sleep support. Kava has stronger evidence for anxiety but comes with concerns about liver toxicity.

Melatonin works through completely different mechanisms, targeting circadian rhythm rather than anxiety.

Summary

Passionflower has centuries of traditional use and modest scientific support for mild anxiety and sleep difficulties. It’s not a substitute for professional treatment of serious anxiety disorders or chronic insomnia, but it may help take the edge off day-to-day stress or occasional sleep troubles.

The evidence base consists mainly of small, short-term studies. We need larger trials to confirm benefits and establish optimal dosing. That said, the safety profile looks reasonable for most adults when used appropriately.

If you want to try passionflower, choose products from reputable manufacturers, start with conservative doses, and pay attention to how your body responds. And as with any supplement, let your healthcare provider know you’re taking it.

References

Miroddi M, Calapai G, Navarra M, Minciullo PL, Gangemi S. Passiflora incarnata L.: ethnopharmacology, clinical application, safety and evaluation of clinical trials. J Ethnopharmacol. 2013;150(3):791-804. doi:10.1016/j.jep.2013.09.047
European Medicines Agency. Assessment report on Passiflora incarnata L., herba. EMA/HMPC/669740/2013. 2014.
Akhondzadeh S, Naghavi HR, Vazirian M, Shayeganpour A, Rashidi H, Khani M. Passionflower in the treatment of generalized anxiety: a pilot double-blind randomized controlled trial with oxazepam. J Clin Pharm Ther. 2001;26(5):363-367. doi:10.1046/j.1365-2710.2001.00367.x
Institute of Medicine Committee on Sleep Medicine and Research. Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem. Washington (DC): National Academies Press; 2006.
Ngan A, Conduit R. A double-blind, placebo-controlled investigation of the effects of Passiflora incarnata (passionflower) herbal tea on subjective sleep quality. Phytother Res. 2011;25(8):1153-1159. doi:10.1002/ptr.3400
Movafegh A, Alizadeh R, Hajimohamadi F, Esfehani F, Nejatfar M. Preoperative oral Passiflora incarnata reduces anxiety in ambulatory surgery patients: a double-blind, placebo-controlled study. Anesth Analg. 2008;106(6):1728-1732. doi:10.1213/ane.0b013e318172c3f9
Akhondzadeh S, Kashani L, Mobaseri M, Hosseini SH, Nikzad S, Khani M. Passionflower in the treatment of opiates withdrawal: a double-blind randomized controlled trial. J Clin Pharm Ther. 2001;26(5):369-373. doi:10.1046/j.1365-2710.2001.00366.x
Fahami F, Asali Z, Aslani A, Fathizadeh N. A comparative study on the effects of Hypericum Perforatum and passion flower on the menopausal symptoms of women referring to Isfahan city health care centers. Iran J Nurs Midwifery Res. 2010;15(4):202-207.
Appel K, Rose T, Fiebich B, Kammler T, Hoffmann C, Weiser D. Modulation of the γ-aminobutyric acid (GABA) system by Passiflora incarnata L. Phytother Res. 2011;25(6):838-843. doi:10.1002/ptr.3352
Solbakken AM, Rorbakken G, Gundersen T. Nature medicine as intoxicant. Tidsskr Nor Laegeforen. 1997;117(8):1140-1141.