This herb has mild sedative properties and is effective for mild to moderate anxiety. A study in the Journal of Clinical Pharmacology Therapeutics looked at the effect of passionflower on 36 people with generalized anxiety disorder. In a 4 week trial 18 people took passionflower extract at a dose of 45 drops per day plus a placebo tablet, and 18 took oxazepam (Serax) at 30 mg per day plus placebo drops. Researchers found that passionflower extract and oxazepam (Serax) were both effective in the treatment of generalized anxiety disorder.
No significant difference was observed between the two compounds at the end of trial. While oxazepam (Serax) showed a rapid onset of action it also had more side effects such as significantly more problems relating to impairment of job performance. (Akhondzadeh S, Naghavi HR, Vazirian M, Shayeganpour A, Rashidi H, Khani M. Passionflower in the treatment of generalized anxiety: a pilot double-blind randomized controlled trial with oxazepam. J Clin Pharm Ther. 2001 Oct;26(5):363-7.)