- Apricot vine
- Passion vine
For Patients & Caregivers
Passionflower may reduce anxiety, but its long-term safety and effectiveness are not known.
Passiflora incarnata is a perennial wildflower that is commonly found in the southern United States. Passionflower extract is contained in many dietary supplement products marketed as sleep aids or anxiety relievers. A handful of studies in humans support these claims, although it is still unknown whether passionflower extracts are safe and effective in the long-term. Scientists are not sure how this herb works, but have speculated that compounds in passionflower may interact with receptors in the brain that would mediate a relaxation response. Studies done in mice suggest that passionflower extracts have mild anti-inflammatory and anti-seizure activity.
Because animal studies show disrupted sexual behavior in male offspring, passionflower should be avoided during pregnancy. It may also interact with certain medications as well as have added effects with St. John’s wort and/or valerian.
To relieve anxiety
One small clinical trial suggested that passionflower may be as effective as oxazepam, a common drug used for treating general anxiety. In addition, another clinical trial showed that passionflower reduced anxiety in presurgical patients. However, the safety and effectiveness of its long-term use are not known.
As a sleep aid, for insomnia
Passionflower may reduce anxiety (see above), which may help induce sleep. A small study showed benefits of passionflower in sleep quality in healthy adults.
To treat nerve pain
Passionflower may help reduce anxiety (see above), and could thereby reduce the perception of pain. However, other than this theoretical association, no scientific evidence supports the use of passionflower for nerve pain.
To treat attention-deficit hyperactivity disorder (ADHD)
One small study in children suggests passionflower may reduce ADHD symptoms similar to a prescription drug but with less side effects. However, larger well-designed clinical trials are needed.
- You are taking pentobarbital: Passionflower may have additive effects.
- You are taking benzodiazepines such as Ativan® or Valium®: Passionflower may increase the sedative effects of these medications.
- You are taking drugs that prolong the QT interval (eg, azithromycin, dasatinib, fingolimod): The QT interval shows the electrical activity in the heart’s lower chambers, the ventricles. Because lab analyses suggest passionflower may also prolong QT interval with large doses, it is not known whether passionflower may have added cardiac effects with these medications.
- You are pregnant: Passionflower should be avoided because it may cause uterine contraction and behavioral dysfunction in offspring.
- Lack of muscle coordination
- Allergic reaction
- Impaired cognitive function
Large doses may result in central nervous system depression and slowed or irregular heart rhythms.
- A 34-year-old woman required hospital admission with symptoms of nausea, vomiting, decreased heart rate, and heart rhythm abnormalities after using a passionflower supplement.
- A patient who self-medicated with valerian and passionflower while on anti-anxiety therapy experienced hand tremors, dizziness, throbbing and muscular fatigue suspected to be caused by using these products together.
For Healthcare Professionals
Passiflora incarnata is a perennial wildflower that is commonly found in the southern United States. Passionflower extract is used in supplemental form by patients to treat insomnia, anxiety, epilepsy, neuralgia, and withdrawal syndromes from opiates or benzodiazepines. It may also be found in over-the-counter preparations to reduce symptoms associated with menopause and hyperactivity.
Animal models suggest antidiabetic (19), antiasthmatic (20), and seizure suppression effects (21). In one study, passionflower reduced seizure severity and immobility periods, and retained brain levels of serotonin and noradrenaline (21). Another study found that P. incarnata extracts produced anxiogenic effects in mice, although two of these extracts also showed an anticonvulsant effect against seizures (6).
In humans, a small pilot study of passionflower for generalized anxiety showed comparable efficacy to oxazepam (3), but a systematic review concluded that randomized controlled studies are needed to confirm such effects (4). In patients undergoing surgery, preoperative passionflower use reduced anxiety (5) (16). In healthy adults, consumption of a low-dose passionflower tea produced short-term benefits in sleep quality (17). Another small study suggests that the effect of passionflower is comparable to a prescription drug in the treatment of ADHD (22).
When used concurrently, passionflower was shown to enhance the pharmacologic effects of St. John’s wort (18).
Theoretically, passionflower may potentiate the sedative effect of central nervous system depressants including benzodiazepines, barbiturates, and alcohol (2). Due to potential adverse effects, passionflower should be avoided during pregnancy (23).
The alkaloid constituents harman and harmaline are thought to produce monoamine oxidase inhibition (1), while maltol and gamma-pyrone derivatives cause activation of gamma amino butyric acid (GABA) receptors that may account for anxiolytic and sedative properties (11). Chrysin has also been identified among the bioactive metabolites with central nervous system (CNS) suppression activity (21).
In vitro, modulation of the GABA system by passionflower includes affinity to GABA(A) and GABA(B) receptors, and effects on GABA uptake (24). Antiradical activities observed are attributed to flavonoids such as isovitexin (25). An isolated benzoflavone moiety is suspected as being the strongest aromatase inhibitor in passionflower, although the flavone chrysin also has these properties (26).
In an animal reproductive and developmental study, passionflower produced sexual behavioral disruption in male adult rats that was not accompanied by alterations in plasma testosterone levels, reproductive-related organs, and glands weights or sperm count, and was potentially attributed to aromatase inhibition (27). In seizure models, protection against post-ictal depression not seen with diazepam controls point to activity from metabolites in passionflower rather than as a result of its seizure suppression effects (21).
Passionflower also exhibits mild anti-inflammatory activity. An ethanolic extract of passionflower reduced carrageenan-induced edema, leukocyte migration, and granuloma formation in mice, although the effect was less than that seen with aspirin (13).
Large doses may result in central nervous system depression and bradycardia, prolonged QTc and ventricular tachycardia (4).
Nausea, vomiting, bradycardia, and abnormal electrocardiogram: ECG changes included non-sustained ventricular tachycardia, QTc prolongation, and nonspecific ST-T wave changes in a 34-year-old woman requiring hospital admission (7).
Hand tremors, dizziness, throbbing and muscular fatigue: In a patient who self-medicated with valerian and passionflower while on lorazepam treatment. An additive or synergistic effect is suspected to have caused these symptoms (14).
Pentobarbital: Passionflower may potentiate the effects of pentobarbital (2).
Benzodiazepines: Passionflower may increase the sedative effects of benzodiazepines by increasing the binding activity of benzodiazepines to GABA receptors (14).
Drugs that prolong the QT interval (eg, azithromycin, dasatinib, fingolimod): The pharmacologic profile of passionflower also suggests prolonged QT interval with large doses (4), and it is not known whether passionflower may have added cardiac effects with these medications.
St. John’s wort: In antidepressant models, passionflower was shown to enhance the potency of St. John’s wort (18).