There is preliminary evidence that passionflower may help restlessness, anxiety or agitation but better research is needed. A recent review of two studies concluded there were insufficient good quality trials to make conclusions about its effect on anxiety, although some research has found it as effective as benzodiazepine drugs, with less job impairment.
There is preliminary evidence from a few small studies that passionflower might be helpful reducing anxiety before a medical ordental procedure.
Another small 2013 study showed preliminary evidence that a combination of passionflower with two other herbs (valerian and hops) may be helpful for insomnia. There is also preliminary evidence that passionflower tea might help sleep quality.
Some studies suggest it may help in opiate, cannabis and alcohol withdrawal. However, there is not enough evidence to draw conclusions about its usefulness in conditions such as heart disease, asthma or sleep.
Side-effects and interactions
Hypersensitivity reactions (hives, skin blood vessel inflammation), occupational asthma and drowsiness have been reported. It may cause dizziness and confusion.
It may interact with some drugs especially blood thinning drugs, antiepileptics, benzodiazepines and barbiturates. It can cause excessive sleepiness if taken together with a sedative drug. Avoid in pregnancy as it may increase uterine contractions.