Passionflower benefits: what the research does and doesn't show

The evidence doesn't support passionflower, in any form, as a treatment for anxiety, insomnia or any other diagnosed condition. Two small placebo-controlled trials exist: one found better anxiety scores than placebo before a stressful medical procedure; the other found better self-rated sleep after a week of nightly tea. Both are small and short.

What the evidence doesn't support

It doesn't support passionflower as a treatment for an anxiety disorder, generalized anxiety, panic attacks, insomnia or any other diagnosed sleep or mental-health condition. It doesn't support the idea that passionflower tea, extract or capsules do anything measurable for someone without the specific circumstance each trial tested — sitting in a pre-surgery waiting room, or already having mild, fluctuating sleep quality. Nobody has tested passionflower against a placebo for longer than a week, in a clinical population, or against a validated diagnostic outcome rather than a self-rated score.

What the trials found

A 2008 randomized, double-blind, placebo-controlled trial gave 60 adults a single 500 mg oral dose of Passiflora incarnata extract, or a placebo, 90 minutes before ambulatory (outpatient) surgery. Anxiety, rated on a numerical scale before dosing and again at 10, 30, 60 and 90 minutes afterward, was significantly better in the passiflora group than placebo. Sedation scores, psychomotor test performance and time to discharge didn't differ between groups. That's one dose, in one specific, time-limited situation — waiting for surgery — in adults who weren't diagnosed with an anxiety disorder.

A 2011 double-blind, placebo-controlled crossover trial had 41 healthy adults (18-35) with mild, self-reported fluctuations in sleep quality drink a cup of Passiflora incarnata herbal tea, or a placebo tea, nightly for a week, with a week off in between. Sleep-diary ratings of sleep quality were significantly better after the passionflower week than the placebo week; five other sleep-diary measures showed no significant difference. Ten of the 41 participants also spent one night per arm in a sleep lab, but the published results don't report a separate finding from that recording — the headline result comes from the self-reported diaries.

Both trials used Passiflora incarnata, the species behind essentially all human passionflower research, including the European Medicines Agency's herbal monograph. Other species sold as passionflower — most notably Passiflora caerulea, a different but commonly cultivated species — haven't been tested in a human trial the same way, so neither of these results says anything about a product made from a different species.

Trial	Population	Dose & form	Result
2008 RCT, n=60	Adults before outpatient surgery	500 mg extract, single dose	Better anxiety scores than placebo; no added sedation
2011 crossover RCT, n=41	Healthy adults with mild sleep complaints	Herbal tea, nightly for a week	Better self-rated sleep quality than placebo tea

Questions people ask

Is passionflower good for anxiety?

The one placebo-controlled trial tested a single dose before a specific, short-term stressor — outpatient surgery — in adults without a diagnosed anxiety disorder. That's a narrow finding, not evidence that passionflower works for anxiety generally or for everyday worry.

Is passionflower good for sleep?

One small trial found better self-rated sleep quality after a week of nightly tea in healthy adults with mild sleep complaints — not people with diagnosed insomnia, and not a result measured any other way than a morning sleep diary.

Can passionflower cause anxiety?

Neither trial reported anxiety as a side effect of passionflower. That's reassuring but limited: between the two trials, fewer than 100 people were studied in total.

How much passionflower is good for anxiety or sleep?

The two trials used different forms at different amounts — a 500 mg single extract dose for the anxiety trial, a cup of tea nightly for the sleep trial — and neither tested a range of doses to find out what amount works best. See how much passionflower should you take a day? for what's actually been tested.

Is lemon balm or passionflower better for anxiety?

This page doesn't rank passionflower against other herbs — the underlying trial quality for herbal research on mood and stress is generally thin, passionflower included, and a head-to-head trial between the two doesn't exist.

When to talk to a doctor

Anxiety or sleep problems that interfere with daily life, work or relationships are worth raising with a doctor. Passionflower is not a treatment for an anxiety disorder or insomnia, and nothing in the two trials above supports using it in place of an evaluation, therapy or a prescribed treatment a doctor might recommend. If you take medication — especially a sedative, sleep medication or anything for anxiety — talk to a doctor before adding any supplement.

Related reading: what is passionflower? A plain guide, how much passionflower should you take a day?, and passionflower and medications: what to check.