Passionflower

What it is

Passionflower is the dried aerial parts of Passiflora incarnata, a perennial climbing plant, taken as a tea, tincture or dry extract. It is one of the oldest herbal calmatives in European and North American use and is registered in the European Union as a traditional herbal medicinal product on the basis of long-standing use rather than trial evidence. Its constituents include flavonoids; no single active principle has been agreed.

What the research says

It is sold for nervousness and sleep. The strongest synthesis, a Cochrane review, found only two eligible randomised trials totalling 198 people and concluded no conclusion could be drawn. A later systematic review of nine trials found most reported reduced anxiety, with the effect weakest in people whose anxiety was mild, and reported no adverse effects in those trials. Regulators register it for traditional use only; EMA's 2014 assessment report notes that conventional clinical safety data are virtually absent.

Evidence grade: Limited evidence.

What goes wrong

A case of ventricular tachycardia with prolonged QT interval followed passionflower ingestion, though causality could not be confirmed. (Source 1)

• Case report, Very low certainty.
• Size: 1 patient.
• Who: a person taking passionflower preparations.
• How long: 2 days of ingestion.
• Result: daily dose corresponded to 1.5 g and 2 g of crude drug over two days; hospital admission for cardiac monitoring and intravenous fluids was required.
• Funding: not applicable.

One case of ventricular tachycardia accompanied by severe nausea, vomiting, drowsiness and prolonged QT interval required hospital admission for cardiac monitoring and intravenous fluid therapy (Fisher et al., 2000).

Hypersensitivity reactions, including one case of hypersensitivity vasculitis, have been reported. (Source 1)

• Case report, Very low certainty.
• Size: 1 reported case of vasculitis.
• Who: users of passionflower preparations.
• How long: not stated.
• Result: no rate is given; the assessment describes hypersensitivity as possible in very rare cases.
• Funding: not applicable.

Hypersensitivity is possible in very rare cases (ESCOP, 2003). One case of hypersensitivity vasculitis has been reported (Smith et al., 1993).

The European regulator records that the minimum required mutagenicity data for passionflower are still not available, and on that basis did not recommend including it in the Community list. (Source 1)

• Official position, Certainty not rated.
• Size: not applicable.
• Who: users of Passiflora incarnata herbal medicinal products.
• How long: not applicable.
• Result: no rate; the assessment also states that conventional clinical safety data are virtually absent and that, in the absence of sufficient data, use during pregnancy and lactation is not recommended.
• Funding: regulatory body.

As the minimum required data on mutagenicity (Ames test) are still not available, an inclusion to the Community list of traditional herbal substances, preparations and combinations thereof for use in traditional herbal medicinal products is not recommended.

What the evidence supports

A systematic review of randomised trials found most reported reduced anxiety after passionflower preparations, with the effect weaker in mild anxiety. (Source 2)

• Systematic review, Low certainty.
• Size: nine clinical trials.
• Who: adults aged 18 and over in neuropsychiatric settings.
• How long: from one day up to 30 days.
• Result: no pooled effect size was calculated; outcomes were measured with differing scales across the included trials.
• Funding: not stated in the abstract.

The majority of studies reported reduced anxiety levels following the administration of Passiflora incarnata preparations, with the effect less evident in people with mild anxiety symptoms.

Within the trials of the 2020 systematic review, no adverse effects on memory or psychometric function were observed. (Source 2)

• Systematic review, Low certainty.
• Size: nine clinical trials.
• Who: adults.
• How long: one day to 30 days.
• Result: no adverse effects reported in the included trials.
• Funding: not stated in the abstract.

No adverse effects, including memory loss or collapse of psychometric functions, were observed.

What the evidence does not support

A Cochrane review found only two eligible randomised trials and concluded that no conclusion about effectiveness could be drawn. (Source 3)

• Systematic review, Very low certainty.
• Size: two studies, 198 participants in total.
• Who: people with a primary anxiety disorder diagnosis.
• How long: not stated in the abstract.
• Result: one trial indicated a lack of difference in efficacy between benzodiazepines and passiflora; the apparent advantages in job performance and drowsiness did not reach statistical significance.
• Funding: not stated in the abstract.

RCTs examining the effectiveness of passiflora for anxiety are too few in number to permit any conclusions to be drawn.

In the Cochrane review the apparent advantages of passionflower over a comparator drug were not statistically significant. (Source 3)

• Systematic review, Very low certainty.
• Size: two studies, 198 participants.
• Who: adults with anxiety disorder.
• How long: not stated.
• Result: improvement in job performance (a post-hoc outcome) and lower drowsiness versus mexazolam both failed to reach statistical significance.
• Funding: not stated in the abstract.

Two studies, with a total of 198 participants, were eligible for inclusion in this review.

Where the evidence is mixed

The trials included in that review were short and used inconsistent outcome measures. (Source 2)

• Systematic review, Low certainty.
• Size: nine clinical trials.
• Who: adults.
• How long: one day to 30 days.
• Result: heterogeneous scales prevented pooling.
• Funding: not stated in the abstract.

The systematic review included nine clinical trials. The duration of the studies included in the analysis varied widely, from one day up to 30 days.

The European Medicines Agency's HMPC position, adopted 25 March 2014, registers passionflower for traditional use only. (Source 4)

• Official position, Certainty not rated.
• Size: not applicable.
• Who: adults using registered traditional herbal medicinal products.
• How long: not applicable.
• Result: indication limited to mild symptoms of mental stress and sleep, on the basis of long-standing use rather than clinical trials.
• Funding: regulatory body.

Traditional herbal medicinal product for use in the specified indication exclusively based upon long-standing use

Where the research disagrees

Whether passionflower has shown an anxiety benefit

• Cochrane review authors (Miyasaka and colleagues, 2007), Cochrane systematic review; two trials, 198 participants: RCTs examining the effectiveness of passiflora for anxiety are too few in number to permit any conclusions to be drawn. (Source 3)
• Authors of a 2020 systematic review in Nutrients, systematic review of nine randomised clinical trials, no pooled effect estimate: The majority of studies reported reduced anxiety levels following the administration of Passiflora incarnata preparations, with the effect less evident in people with mild anxiety symptoms. (Source 2)

How much

• Reference intake: No reference intake exists; passionflower is not a nutrient. The EMA registers it as a traditional herbal medicinal product rather than setting an intake. (Source 4)
• Upper limit: No tolerable upper intake level or acceptable daily intake has been set. EMA's 2014 assessment report states that conventional clinical safety data are virtually absent. (Source 1)
• Studied: EMA's monograph describes a traditional-use herbal tea preparation of 1-2 g of the comminuted herbal substance in 150 ml of boiling water, taken 1 to 4 times daily. (Source 4)
• Studied: The case of ventricular tachycardia followed a daily dose corresponding to 1.5 g and then 2 g of crude drug over two days. (Source 1)

A common belief, and what the research shows

The belief: Passionflower is proven to calm anxiety and is completely free of side effects.

What the research shows: The Cochrane review states that "RCTs examining the effectiveness of passiflora for anxiety are too few in number to permit any conclusions to be drawn." On safety, the European regulator writes that "Conventional clinical safety data are virtually absent", and records "One case of ventricular tachycardia accompanied by severe nausea, vomiting, drowsiness and prolonged QT interval required hospital admission for cardiac monitoring and intravenous fluid therapy (Fisher et al., 2000)."

Questions and answers

What is it?

Passionflower is a perennial climbing plant, Passiflora incarnata, whose dried above-ground parts are used medicinally as tea, tincture or extract. It is not the same as the edible passion fruit vine species usually sold as fruit. It has been used for a long time as a calming herb. (Source 2)

What does it do in the body?

It is taken for stress, restlessness and sleep. The literature suggests a calming effect, but no single active constituent or mechanism has been established, and the clinical work uses many different scales rather than one accepted outcome. (Source 2)

Is it good or bad for you?

Neither clearly. The Cochrane review found too few randomised trials to reach any conclusion about whether it works for anxiety. Later trials mostly point in a favourable direction for short-term anxiety, but they are small and brief. Harms appear uncommon, with isolated serious case reports including one of ventricular tachycardia. (Source 3)

How do you get more of it?

It is taken as a herbal preparation, not obtained from food. The European Medicines Agency describes a traditional infusion made from the comminuted dried herb, and also registers tinctures and dry extracts. These are traditional-use preparations rather than doses validated by trials. (Source 4)

If it is harmful, what reduces it?

It is not a substance that accumulates in the body and needs removing. Where a person reacts badly, the relevant action is to stop. The only contraindication the European regulator lists is hypersensitivity to the herb, and hypersensitivity reactions including one vasculitis case have been reported. (Source 1)

Why might someone be low in it or missing it?

Does not apply. Passionflower is a herb, not a nutrient the body requires, so there is no deficiency state and no reason a person would be low in it. Its registered role is as a traditional herbal medicine for mild symptoms. (Source 4)

Which whole foods contain it or feed it?

No staple whole food contains medicinal passionflower. The closest everyday form is the herbal infusion made from the dried herb itself. Edible passion fruit comes from related Passiflora species and is not the preparation studied. (Source 4)

What happens if you do not have it?

Nothing. There is no consequence of never taking passionflower, because it is not required by the body. Not taking it simply means forgoing a herbal preparation whose benefit has not been established in randomised trials. (Source 3)

How can you test for it?

There is no clinical test of a person's passionflower status, because there is no deficiency or normal range to measure. In the trials, what was measured was the outcome rather than the substance, using a variety of anxiety and psychometric scales, which is one reason results cannot easily be pooled. (Source 2)

We searched: Searched the Cochrane review, the 2020 systematic review of nine trials and the EMA assessment report for any validated biomarker or status assay for Passiflora incarnata; none is described.

References

1. European Medicines Agency, Committee on Herbal Medicinal Products (HMPC). Assessment report on Passiflora incarnata L., herba (final; EMA/HMPC/669738/2013), adopted 25 March 2014. 2014. Read the source
2. Nutrients. Passiflora incarnata in Neuropsychiatric Disorders-A Systematic Review. 2020. PMID 33352740, DOI 10.3390/nu12123894. Read the source
3. Cochrane Database of Systematic Reviews. Passiflora for anxiety disorder. 2007. PMID 17253512, DOI 10.1002/14651858.CD004518.pub2. Read the source
4. European Medicines Agency, Committee on Herbal Medicinal Products (HMPC). Community herbal monograph on Passiflora incarnata L., herba. 2014. Read the source