Side Effects of Passiflora Incarnata

Passiflora incarnata, or Passionflower, is a perennial vine with lavender flowers and green trilobed leaves. Due to its potent flavonoid and alkaloid content, the plant has been used traditionally as an herbal remedy for stress and anxiety, high blood pressure, and spastic muscle conditions. Since it is not a narcotic and nonaddictive, Passiflora incarnata is also a favorite remedy for insomnia. It is generally safe to use as a tea, extract, or tincture, but some negative side effects have been reported in the medical literature.

Drowsiness

Passiflora incarnata is a central nervous system depressant. Its flavonoid constituents have sedative properties and can induce sleep. Do not drive or operate potentially dangerous machinery when taking this herb.

Do not take Passiflora incarnata with other central nervous system depressants, such as benzodiazepines, barbiturates, narcotics, antidepressants or alcohol, because the combination can cause serious side effects. In the May 13, 2009 issue of "Phytotherapy Research," Carrasco, Vallejo, Pardo-de-Santayana, Peral, Martin, and Altimiras found that a patient who used Passiflora incarnata with another herb, Valeriana officinalis, and the benzodiazepine drug lorazepam suffered dizziness, shaking hands, throbbing and muscle fatigue. They concluded that the active ingredients in the herbs increased the effects of the lorazepam, resulting in severe side effects.

The tincture form of Passiflora incarnata may contain alcohol as a base. If you have diabetes or liver disease, this may be a concern. Use alcoholic beverages cautiously when taking the herb tincture.

Allergies

Allergic reactions to Passiflora incarnata are rare, but have occurred. In the January 1993 issue of the "British Journal of Rheumatology," Smith, Chalmers and Nuki reported the case of an elderly man who was given herbal tablets containing Passiflora incarnata for his insomnia. He developed a small and short-lived case of vasculitis (inflammation of the blood vessels) that his doctors attributed to the herb. If you experience itching, burning, or blistering, discontinue use of the herb.

Nausea and Vomiting

Passiflora incarnata may cause nausea and vomiting even if you take the recommended dose for the tincture (10 to 60 drops, three times per day) or the extract (10 to 30 drops, three times per day). In the 2000 issue of "Clinical Toxicology," Fisher, Purcell and Le Couteur cite the case of a female who experienced severe nausea and vomiting after taking a normal dose of the herb. If you experience these side effects, discontinue use immediately.

MAO Inhibitor

The alkaloid components in Passiflora incarnata include the monoamine oxidase inhibitors (MAO-inhibitors) harmaline, harmine and harman. MAO-inhibitors are prescribed for the treatment of depression. Do not take Passiflora incarnata with other antidepressant MAO-inhibitors as it may enhance the effects of those drugs.

Do not take Passiflora incarnata if you are using two other classes of antidepressants, tricyclic antidepressants and serotonin reuptake inhibitors, because the combination may cause excessive sedation or low blood pressure.

Bleeding

Passiflora incarnata contains scopoletin and umbelliferone, which are coumarin compounds that act as blood thinners. A synthetic form of coumarin is used in the anticoagulant drug warfarin. Do not take Passiflora incarnata with warfarin or other drugs that may cause bleeding, including aspirin, heparin, ibuprofen, naproxen and anti-platelet drugs.

Do not use Passiflora incarnata with other plants or herbal products that can cause bleeding, such as Ginkgo biloba, since the combination may increase the overall risk of bleeding.