Sedatives
An animal study has demonstrated that passionflower enhances the effects of pentobarbital, a medication used to promote sleep and for seizure disorders. Caution is advised when taking passionflower with sedatives because the herb may increase the effects of these substances. Additional examples of medications with sedative properties include certain antihistamines, such as diphenhydramine and hydroxyzine; drugs for anxiety, like a class called benzodiazipines including diazepam and lorazepam; and other medications used to treat insomnia. Interestingly, passionflower appears to work similarly to benzodiazipines.