Passionflower (Passiflora incarnata) was used historically in South America and later in Europe as a "calming" herb for anxiety, insomnia, seizures, and hysteria. It is still used today to treat anxiety and insomnia. Although scientists aren't sure, it is believed that passionflower works by increasing levels of a chemical called gamma-aminobutyric acid (GABA) in the brain. GABA lowers the activity of some brain cells, resulting in relaxation.

Passionflower tends to have less potent effects than valerian (Valeriana officinalis) or kava (Piper methysticum), other calming herbs, and is often combined with valerian, lemon balm (Melissa officinalis), or other herbs that treat anxiety. No scientific studies have successfully evaluated passionflower for anxiety or insomnia, however; since it is often combined with other calming herbs, it is difficult to tell what the effects of passionflower alone might be.

For example, one study of 36 people with generalized anxiety disorder found that passionflower was as effective as the drug oxazepam for treating symptoms; however, the study lacked a placebo group, so it is not considered to be definitive. In another study of 91 people with anxiety symptoms, researchers found that an herbal European product containing passionflower and other herbal sedatives significantly reduced symptoms compared to placebo. An earlier study, however, failed to find any benefits from an herbal tablet containing passionflower, valerian, and other sedative herbs.

Native to southeastern parts of the Western Hemisphere, passionflower is now grown throughout Europe. It is a perennial climbing vine with herbaceous shoots and a sturdy woody stem that grows to a length of nearly 10 meters (about 32 feet). Each flower has 5 white petals and 5 sepals that vary in color from magenta to blue. According to folklore, passionflower was given its name because its corona resembles the crown of thorns worn by Jesus during the crucifixion. The passionflower's ripe fruit is an egg-shaped berry that may be yellow or purple. Some kinds of passionfruit are edible.

The above-ground parts (flowers, leaves, and stems) of the passionflower are used for medicinal purposes.

Available forms include the following:

• Infusions
• Teas
• Liquid extracts
• Tinctures

Pediatric

Because no studies have examined the effects of passionflower in children, you should only give passionflower to a child under a doctor's supervision. Adjust the recommended adult dose to account for the child's weight. Most herbal dosages for adults are calculated on the basis of a 150 lb (70 kg) adult. So if a child weighs 50 lb (20 - 25 kg), the appropriate dose of passionflower for this child would be 1/3 of the adult dosage.

Adult

The following are recommended adult doses for passionflower:

• Tea: Steep 0.5 - 2 g (about 1tsp.) of dried herb in 1 cup boiling water for 10 minutes; strain and cool. For anxiety, drink 3 to 4 cups per day. For insomnia, drink one cup an hour before going to bed.
• Fluid extract (1:1 in 25% alcohol): 10 - 30 drops, three times a day
• Tincture (1:5 in 45% alcohol): 10 - 60 drops, three times a day

The use of herbs is a time-honored approach to strengthening the body and treating disease. Herbs, however, can trigger side effects and can interact with other herbs, supplements, or medications. For these reasons, herbs should be taken with care, under the supervision of a health care provider.

Do not take passionflower if you are pregnant or breastfeeding.

For others, passionflower is generally considered to be safe and nontoxic in recommended doses.

Passionflower may interact with the following medications:

Sedatives (drugs that cause sleepiness) -- Because of its calming effect, passionflower may increase the effects of sedative medications. These can include:

• Anticonvulsants such as phenytoin (Dilantin)
• Barbiturates
• Benzodiazepines such as alprazolam (Xanax) and diazepam (Valium)
• Drugs for insomnia, such as zolpidem (Ambien), zaleplon (Sonata), eszopiclone (Lunesta), ramelteon (Rozerem)
• Tricyclic antidepressants, such as amitriptyline (Elavil), amoxapine, doxepin (Sinequan), and nortriptyline (Pamelor)

Antiplatelets and anticoagulants (blood thinners) -- Passionflower may increase the amount of time blood needs to clot, so it could make the effects of blood-thinning medications stronger and increase your risk of bleeding. Blood-thinning drugs include:

• Clopidogrel (Plavix)
• Warfarin (Coumadin)

Monoamine oxidase inhibitors (MAO inhibitors or MAOIs) -- MAO inhibitors are an older class of antidepressants that are not often prescribed now. Theoretically, passionflower might increase the effects of MAO inhibitors, as well as their side effects, which can be dangerous. These drugs include:

• Isocarboxazid (Marplan)
• Phenelzine (Nardil)
• Tranylcypromine (Parnate)

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