Passionflower for anxiety and sleep: evidence, surgery cautions and UK status

Passionflower is a vine native to the southeastern United States and to Central and South America. Spanish explorers learned of its sedative use in the sixteenth century and carried it to Europe, where it became a cultivated medicinal plant. Today it is promoted for anxiety, including anxiety before surgery, sleep problems, stress, ADHD and pain.

NIH reports that its effect on anxiety and other conditions has not been studied extensively. The evidence for anxiety and insomnia is the strongest of its claimed uses, but still thin, and the evidence for other conditions such as ADHD, heart failure, menopausal symptoms, fibromyalgia and stress is not enough to say whether it helps.

NIH summarises a small amount of research suggesting that oral passionflower might reduce anxiety symptoms, including anxiety before a surgical or dental procedure, though conclusions are not definite. A small amount of research also suggests it might improve total sleep time in adults with insomnia, but its effects on time to fall asleep and staying asleep are mixed.

A 2020 systematic review in Nutrients included nine randomised clinical trials, lasting from one day to thirty days, in adults. Most reported lower anxiety after passionflower preparations, with the effect less evident in people with mild anxiety symptoms. No adverse effects, including memory loss or loss of psychometric function, were observed. The authors concluded that it may be helpful for some symptoms in neuropsychiatric patients, while the short durations and varied rating scales limit what can be concluded for long-term care.

• Short trials, with different preparations and scales.

• Most data concern symptoms of anxiety rather than diagnosed anxiety disorders treated over months.

• Sleep results are mixed and based on small numbers.

• None of this compares passionflower head to head with therapy or prescribed medicines.

The Committee on Herbal Medicinal Products concluded that, on the basis of long-standing use, passion flower preparations can be used for relief of mild symptoms of mental stress and to aid sleep. They should be used only in adults and adolescents over 12, and a doctor or qualified healthcare practitioner should be consulted if symptoms last more than two weeks or worsen during use.

This is a traditional-use conclusion: effectiveness is plausible, and the herb has been used safely for at least 30 years including at least 15 in the EU, for a condition that does not need medical supervision. The committee noted published clinical studies but felt the low patient numbers and serious design shortcomings prevented firm conclusions. At the time no side effects had been reported with the medicines it assessed.

NIH calls passionflower likely safe as a food flavouring and possibly safe as a tea for up to seven nights or as a daily extract for up to eight weeks. Possible side effects include drowsiness, dizziness and confusion. It is not known whether skin application is safe.

The surgical caution is important and often missed. NIH warns that passionflower taken alongside anaesthesia or other medicines used before and after surgery might slow the nervous system too much, and advises talking to your clinician if you take it within two weeks of scheduled surgery. Tell the pre-operative assessment team about every herbal product, including teas. NIH also says passionflower should not be used during pregnancy because it may induce uterine contractions, and little is known about breastfeeding.

Because of the sedative effect, combining it with alcohol, sleeping tablets, benzodiazepines, opioids or sedating antihistamines is unwise, and driving or operating machinery should wait until you know how it affects you.

Persistent anxiety or insomnia has effective, evidence-based treatments available through a GP and NHS Talking Therapies, including talking therapies and, where appropriate, medicines. A herb may be a harmless adjunct for mild, short-term symptoms, but should not delay assessment for panic attacks, constant worry that affects daily life, low mood, or sleep problems lasting weeks. Seek urgent help through NHS 111 or 999 if you have thoughts of harming yourself.

A passionflower product sold with a medicinal purpose, such as easing stress or helping sleep, should carry a traditional herbal registration number and mark, showing that the MHRA assessed safety, quality and patient information. Teas and capsules sold as foods should not make medical claims, and the MHRA can treat a product as a medicine based on its claims, ingredients and presentation. The NHS advises asking a pharmacist before taking any herbal product with prescribed medicines, and against buying unlicensed herbal medicines online.