Passiflora incarnata in Neuropsychiatric Disorders-A Systematic Review.

The short version

This systematic review pooled nine randomised clinical trials to ask whether passionflower (Passiflora incarnata) helps with anxiety, sleep and related neuropsychiatric symptoms. Passionflower is a perennial climbing vine whose aerial parts, flowers and fruit are used medicinally, and whose activity is attributed to flavonoids such as apigenin and luteolin and to flavonoid glycosides including vitexin and isovitexin. The European Medicines Agency recognised it as a medicinal product in a 2014 herbal monograph. The review frames the problem as stress — the body's response to physical and psychological stressors, which becomes pathological when prolonged and can impair concentration and memory. The authors searched PubMed, Embase and ClinicalTrials.gov to October 2019 and screened 417 records down to nine trials run between 2017 and 2019, five of them in Iran. Participants were all adults, between 16 and 128 per trial, and eight of the nine trials enrolled healthy volunteers rather than diagnosed patients. Preparations varied widely — drops, tablets, syrup, a standardised extract and herbal tea — over periods from a single day to 30 days. Anxiety was measured with instruments including the State-Trait Anxiety Inventory and the Corah Dental Anxiety Scale, sedation with the Ramsey scale, and sleep with polysomnography. Most trials found reduced anxiety, though the benefit was smaller in people whose anxiety was mild to begin with. In generalised anxiety disorder, 45 drops daily for 28 days matched oxazepam without impairing work performance. Before surgery, 500 mg tablets lowered anxiety more than oxazepam, and a 700 mg per 5 mL syrup given 30 minutes before spinal anaesthesia reduced anxiety with haemodynamics unchanged. Compared with midazolam before wisdom-tooth extraction, 260 mg gave similar calming with markedly less somnolence (50% versus 82.5%) and no amnesia at all, against 20% on midazolam — although more participants would still choose midazolam again (52% versus 27.5%), which the authors attribute to that same amnesia preventing negative memories. Herbal tea drunk nightly for a week improved self-reported sleep quality by 5.2% over placebo. No adverse effects, memory loss or collapse of psychometric function were reported anywhere in the review. The practical reading is that passionflower performs comparably to two established sedatives for procedural anxiety, with a different side-effect profile — less somnolence, no amnesia — which may matter where alertness is wanted afterwards. The evidence is genuinely limited, though: nine small trials, too heterogeneous to pool statistically, three of them rated low quality, and most never recorded which part of the plant was used. Its anxiolytic action is thought to work through the GABA system. Larger trials across more varied populations are needed before firm dosing guidance is possible.

Key findings

• Across nine randomised trials, passionflower reduced anxiety about as effectively as the sedative drugs oxazepam and midazolam, though the benefit was smaller in people whose anxiety was already mild.
• Before dental surgery, passionflower caused far less drowsiness than midazolam (50% versus 82.5% of patients) and caused no amnesia at all, whereas one in five midazolam patients could not remember the procedure.
• Drinking passionflower tea nightly for one week improved self-reported sleep quality by an average of 5.2% compared with a placebo tea.
• No adverse effects, memory loss or loss of psychometric function (measurable thinking and coordination skills) were observed in any of the nine trials.
• The evidence remains limited: the trials were small (16 to 128 people), too different from one another to combine statistically, and most did not record which part of the plant was used.

Common questions