Passiflora incarnata is a perennial wildflower that is commonly found in the southern United States. Passionflower extract is contained in many dietary supplement products marketed as sleep aids or anxiety relievers. A handful of studies in humans support these claims, although it is still unknown whether passionflower extracts are safe and effective in the long-term. Scientists are not sure how this herb works, but have speculated that compounds in passionflower may interact with receptors in the brain that would mediate a relaxation response. Studies done in mice suggest that passionflower extracts have mild anti-inflammatory and anti-seizure activity.
Because animal studies show disrupted sexual behavior in male offspring, passionflower should be avoided during pregnancy. It may also interact with certain medications as well as have added effects with St. John's wortand/or valerian.