In 1985, Germany's Commission E officially approved passionflower as a treatment for "nervous unrest." The herb is considered to be a mildly effective treatment for anxiety and insomnia, less potent than kava and valerian, but nonetheless useful. Like melissa (lemon balm), chamomile, and valerian, passionflower is also used for nervous stomach.

However, there is only weak supporting scientific evidence that passionflower works for these purposes. Preliminary trials suggest that passionflower might be helpful for anxiety^9,14 and chemical dependency.¹⁰Animal studiessuggest that passionflower extracts can reduce agitation and prolong sleep.^1,11-13

The active ingredients in passionflower are not known.

What Is the Scientific Evidence for Passionflower?

Anxiety

A 4-week double-blind study of 36 individuals with anxiety(specifically, generalized anxiety disorder) compared passionflower to the standard drug oxazepam.⁹Oxazepam worked more quickly, but by the end of the 4-week trial, both treatments proved equally effective. Furthermore, passionflower showed a comparative advantage in terms of side-effects: use of oxazepam was associated with more job-related problems (such as, daytime drowsiness). And, in a placebo-controlled trial involving 60 surgical patients, passionflower significantly reduced anxiety up to 90 minutes prior to surgery.¹⁴

Chemical Dependency

A 14-day, double-blind trial enrolled 65 men addicted to opiate drugs and compared the effectiveness of passionflower and the drug clonidine together against clonidine alone.¹⁰ Clonidine is a drug widely used to assist narcotic withdrawal. It effectively reduces physical symptoms such as increased blood pressure. However, clonidine does not help emotional symptoms, such as drug craving, anxiety, irritability, agitation, and depression. These symptoms can be quite severe and often cause enrollees in drug treatment programs to end participation. In this 14 day study, the use of passionflower along with clonidine significantly eased the emotional aspects of withdrawal as compared to clonidine alone.

Dosage

The proper dosage of passionflower is 1 cup 3 times daily of a tea made by steeping 1 teaspoon of dried leaves for 10 to 15 minutes. Passionflower tinctures and powdered extracts should be taken according to the label instructions.

Safety Issues

Passionflower is on the FDA's GRAS (Generally Recognized as Safe) list.

The alkaloids harman and harmaline found in passionflower have been found to act somewhat like the drugs known as MAO inhibitors and also to stimulate the uterus,^3,4but whether whole passionflower has these effects remains unknown. Passionflower might increase the action of sedative medications.^5,6,7Finally, there are five case reports from Norway of individuals becoming temporarily mentally impaired from a combination herbal product containing passionflower.⁸ It is not clear whether the other ingredients may have played a role.

Safety has not been established for pregnant or nursing mothers, very young children, or those with severe liver or kidney disease.

Interactions You Should Know About

If you are taking:

• Sedative medications: Passionflower might exaggerate their effect.