Passionflower (Passiflora incarnata) is a creeping perennial vine with white, purple-tinged flowers and orange berries that grows to a height of up to 30 ft (9 m).
First used by Native Americans and the Aztecs of Mexico as a sedative, passionflower has been a popular folk remedy for centuries in Europe and North America. Other names for passionflower include maypop, granadilla, passion vine, and apricot vine.
The herb, which is generally used today to alleviate anxiety and insomnia, received its curious name from the Spanish conquistadors who overran Mexico and Peru in the sixteenth century.
In the flowers of the vine, they saw various symbols of the Passion of Christ, which in Christian tradition refers to the period of time between the Last Supper and Christ’s death.
In the Spaniard’s elaborate analogy, the corona in the center of the flower was thought to resemble the crown of thorns worn by Jesus during the crucifixion. The flower’s tendrils symbolized whips, the five stamens represented Christ’s wounds, the total number of petals corresponded to the 10 faithful apostles (Peter and Judas did not make the cut), and so on.
While there are over 400 species belonging to the genus Passiflora, the variety used for medicinal purposes is called incarnata, which can be translated "embodied".
The plant is obtained primarily from the southern United States, India, and the West Indies, though passionflower also grows in Mexico as well as Central and South America. Only the parts of the plant that grow above the ground are used as a drug, in fresh and dried form.
Some investigations of passionflower have been conducted in humans; in addition, animal and other studies suggest that the herb has sedative, anxiolytic, and antispasmodic properties. The German Commission E, considered an authoritative source of information on alternative remedies, reported that passionflower appears to reduce restlessness in animals.
In a 1988 study involving rats that was published in a German journal of pharmacology, passionflower was shown to prolong sleep, reduce motor activity, and protect the rodents from convulsions. Despite findings such as these, researchers have been unable to identify the herb’s active ingredients.
Attention has focused on flavonoids (medicinal passionflower contains up to 2.5% of these chemicals); maltol; and harmala alkaloids such as harman, harmine, harmaline, and harmalol. (The Germans attempted to use harmine as a truth serum during World War II because of the chemical’s reputation for inducing a euphoria-like state.)
Some researchers speculate that it is the interaction, or synergy, of several chemicals in passionflower that is responsible for the herb’s therapeutic effects.
Although it has not been approved by the Food and Drug Administration (FDA), passionflower is mainly used in the United States and Europe to relieve anxiety, restlessness, and insomnia.
It is also recommended for the relief of nausea caused by nervousness or anxiety. The herb appears to work, at least in part, by mildly depressing the central nervous system and preventing muscle spasms.
In its capacity as a sedative and sleep aid, passionflower has been endorsed by several important European research organizations. For over 15 years, passionflower has been approved by Commission E for the treatment of nervous unrest.
The European Scientific Cooperative on Phytotherapy has approved the herb for use in people who experience tension, restlessness, and insomnia associated with irritability. Passionflower is listed in many national pharmacopoeiae as a drug plant.
Passionflower is often used in combination with other sedative plants. In the United Kingdom, it is an ingredient in several dozen over-the-counter (OTC) sedatives.
In Germany, the herb is used as an ingredient in sedative preparations that also include valerian and lemon balm. The standardized sedative tea formula approved by Commission E contains 30% passionflower, 40% valerian root, and 30% lemon balm. Passionflower is also used in Germany in a special sedative tea for children.
The ingredients of this tea typically include 30% passionflower, 30% lemon balm, 30% lavender flower, and 10% St. John’s wort. In combination with hawthorn, passionflower is also used to alleviate digestive spasms associated with gastritis and colitis.
In the past, passionflower was approved by the FDA as an ingredient in OTC sleep aids and sedative products. This approval was revoked in 1978 during a review by the agency, but not because the reviewers found passionflower to be unsafe or ineffective.
Drug manufacturers were responsible for submitting information about the safety and effectiveness of OTC medications under review by the FDA. No companies submitted data for passionflower, so the herb was denied approval because it had no sponsors.
Throughout its history, passionflower has been used to treat a variety of medical problems in addition to those mentioned above. These include epilepsy, diarrhea, neuralgia, asthma, whooping cough, seizures, painful menstruation, and hemorrhoids (when used externally).
Some herbalists also recommend passionflower as a treatment for Parkinson’s disease, based on their belief that the harmine and harmaline in the herb may help to counteract the effects of the disorder. As of 2000, these additional uses for passionflower are considered speculative.
In 2002, a team of American researchers published a report finding that passionflower shows promise as a chemopreventive for cancer. The scientists found that passionflower extract inhibits an early antigen of Epstein-Barr virus, which suggests that it may also inhibit the growth of cancerous tumors.
Recommended dosages of passionflower generally range from 4–8 g of herb a day. While it is typically used in preparations containing other sedative ingredients, it may also be used alone.
Passionflower tea can be prepared by steeping 1 teaspoonful of the herb in 150 ml of simmering water. The mixture should be strained after about 10 minutes. Dosage is usually two or three cups of tea a day, taken during the day and a half-hour before going to bed.
The liquid extract preparation is usually taken three times a day in doses of 0.5–1.0 ml. Dosage for the tincture is 0.5–2.0 ml three times a day. Tablets containing passionflower are available in the United Kingdom. Persons who use a combination product containing passionflower should follow the package directions for use.
Passionflower is not known to be harmful when taken in recommended dosages, though there are some precautions to consider. The herb contains two potentially dangerous alkaloids called harman and harmaline. In large amounts, these chemicals may stimulate the tissue of the uterus.
However, most authorities believe that the amounts of harman and harmaline contained in medicinal passionflower are too small to have an adverse effect when the herb is used in normal amounts. Caution should also be exercised when combining passionflower with certain medications (see below).
While self-care measures such as passionflower may be effective in relieving anxiety or insomnia, these problems may be a symptom of a more serious psychological disorder that requires consultation with a mental health professional.
Nighttime sleep aids should not be used for longer than two weeks without seeking medical advice. Due to lack of sufficient medical study, passionflower should be used with caution in children, women who are pregnant or breast-feeding, and people with liver or kidney disease.
When taken in recommended dosages, passionflower has not been associated with any significant or bothersome side effects.
Passionflower has the potential to interact adversely with certain medications. The harman and harmaline in passionflower may increase the effects of prescription antidepressants called monoamine oxidase inhibitors (MAOIs), which are generally used to treat depression, panic attacks, and eating disorders. Passionflower may also increase the effects of OTC sedatives as well as those sold by prescription.