Passionflower (Passiflora incarnata) has a long history of use in traditional herbal medicine, especially in North and South America and Europe, where it has been used to support relaxation and treat anxiety and insomnia. Scientifically, several small clinical studies and animal experiments suggest that passionflower may have anxiolytic (anxiety-reducing) effects. Proposed mechanisms include modulation of the gamma-aminobutyric acid (GABA) system in the brain, which is also targeted by conventional anti-anxiety medications like benzodiazepines.

Human research, while limited, includes randomized controlled trials in which passionflower extracts have been compared to placebo and to prescription medications. For example, a 2001 double-blind study found passionflower to be as effective as oxazepam (a benzodiazepine) in treating generalized anxiety disorder, though with fewer side effects. Other studies have reported reduced anxiety in patients undergoing dental procedures or surgery when given passionflower extracts.

However, the overall quality, size, and duration of these studies are generally considered low, with methodological weaknesses and small sample sizes. Systematic reviews and meta-analyses have concluded that, while there is some evidence for passionflower’s efficacy in anxiety, the data are not strong enough to make firm recommendations, and more rigorous research is needed. Therefore, the evidence is rated as moderate to low (2/5), but there is both historical tradition and some scientific support for its use.