Passionflower was well tolerated in its trials, and NCCIH names 3 possible side effects: drowsiness, dizziness and confusion. The larger risk is combining it with alcohol or 1 of many sedative drugs.
This page covers both, plus pregnancy, driving and the liver question people keep asking.
Quick Answer: What Are Passionflower's Side Effects?
In trials passionflower was well tolerated, and NCCIH lists drowsiness, dizziness and confusion as possible side effects. The bigger risks are interactions: alcohol, benzodiazepines, sleeping pills, opioids, anesthesia and other sedating herbs may add to its effect. NCCIH says to avoid it in pregnancy and to tell your provider if surgery is within 2 weeks.
Key Takeaways
- NCCIH lists 3 possible side effects: drowsiness, dizziness and confusion.
- Alcohol plus passionflower means 2 things that slow the nervous system together.
- Tell your provider if surgery or dental sedation is within 2 weeks.
- Pregnancy is 1 firm avoid, because it may induce uterine contractions.
- The 1 fatal liver case on PubMed also involved kava, not passionflower alone.
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The Side Effects Actually Reported
Most people in the trials reported nothing troublesome. The effects that do appear follow from what the herb is for.
- Drowsiness: The most predictable, and the reason for the driving rule.
- Dizziness: Listed by NCCIH, and seen in the case reports.
- Confusion: Uncommon, and more likely when stacked with other sedatives.
- Nausea and vomiting: Reported in 1 serious case.
NCCIH lists drowsiness, dizziness and confusion, and describes daily extract as possibly safe for up to 8 weeks.[1]Passionflower: Usefulness and Safety — National Center for Complementary and Integrative Health View source
Which species these warnings apply to is explained in the plant behind the supplement.
What the Case Reports Show
PubMed holds 8 case reports that mention passionflower. Four describe harm in someone who took it.
| Report | What happened | Taken with |
|---|---|---|
| 2000, 1 woman | Nausea, vomiting, drowsiness, heart rhythm changes | Passionflower alone, normal doses |
| 1997, 5 patients | Admitted with altered consciousness | A passionflower product, Relaxir |
| 2009, 1 man | Tremor, dizziness, muscle fatigue | Valerian and lorazepam |
| 2003, 1 patient | Fatal liver failure | A product containing kava |
The most serious single-herb case was a 34-year-old woman with vomiting and heart rhythm changes at normal doses.[2]Toxicity of Passiflora incarnata L. — Journal of Toxicology: Clinical Toxicology (2000) View source In a Norwegian report, 5 patients were admitted with altered consciousness after a passionflower product.[3]Nature medicine as intoxicant (Relaxir case series) — Tidsskrift for den Norske Laegeforening (1997) View source
What Not to Mix It With
This is the section that matters most, because the risk lives in combinations.
- Alcohol: Both slow the nervous system.
- Benzodiazepines: Such as lorazepam, alprazolam or diazepam.
- Sleeping pills: Including zolpidem and sedating antihistamines.
- Opioids: Prescription painkillers slow breathing and alertness.
- Other sedating herbs: Valerian, kava, hops and California poppy.
A man on lorazepam who added valerian and passionflower developed tremor, dizziness and muscle fatigue, which the authors attributed to additive effects at GABA receptors.[4]Interactions of Valeriana officinalis L. and Passiflora incarnata L. in a patient treated with lorazepam — Phytotherapy Research (2009) View source The trials that gave it before surgery did so under supervision, as the pre-surgery anxiety studies describe.
Alcohol and Driving
These 2 deserve their own section, because both are ordinary evening habits.
- Alcohol: Do not drink on the evenings you take it.
- Tinctures: Most, including ours, are made with alcohol.
- Driving: Not until you know how it affects you.
- Machinery: The same rule applies to tools and ladders.
Reassuringly, a single dose before spinal anesthesia did not change psychomotor test results.[5]Passiflora incarnata Linneaus as an anxiolytic before spinal anesthesia — Journal of Anesthesia (2012) View source That was 1 dose in a hospital, without alcohol, which is why it does not license driving.
Pregnancy and Breastfeeding
This is the firmest rule on the page.
- Pregnancy: Avoid, because it may induce uterine contractions.
- Trying to conceive: Stop before, not after, a positive test.
- Breastfeeding: Little is known, so avoid it.
- Teas count: Passionflower tea is still passionflower.
The only human pregnancy data is 5 women treated for depression or anxiety. Complications included 1 neonatal death, though their illness may have contributed.[6]Pregnancy outcomes in psychiatric patients treated with passiflora incarnata — Complementary Therapies in Medicine (2018) View source The duration limits are in a sensible dose and duration.
The Liver Question
People ask whether passionflower is hard on the liver. The honest answer is that the evidence points elsewhere.
- The fatal case: A product combining kava and passionflower.
- What was blamed: Kava, which carries known liver warnings.
- Passionflower alone: No liver failure case found on PubMed.
- Still sensible: Tell your doctor if you have liver disease.
The 2003 case of fatal liver failure involved a natural therapy containing kava.[7]Fatal fulminant hepatic failure induced by a natural therapy containing kava — Medical Journal of Australia (2003) View source Blends are why the label matters: check every herb in a formula, not just the first.
Who Should Avoid It
Put together, the list is short and specific.
- Avoid: Pregnancy, breastfeeding and children.
- Ask first: Anyone on sedatives, opioids or anxiety medication.
- Ask first: Anyone with surgery planned within 2 weeks.
- Choose carefully: Anyone avoiding alcohol entirely.
If alcohol is the concern, the capsule format, which contains no alcohol, removes that 1 variable.
Stop and Speak to a Clinician If
- You take a benzodiazepine, a sleeping pill, an opioid or another sedating prescription
- You drink alcohol in the evening, or need to drive after taking it
- You already take valerian, kava, hops or another sedating herb
- You are pregnant, trying to conceive or breastfeeding
- You have surgery or a dental procedure with sedation within 2 weeks
Frequently Asked Questions
What are the side effects of passionflower? +
NCCIH lists 3: drowsiness, dizziness and confusion. Nausea, vomiting and heart rhythm changes appear in 1 serious case report.
Is passionflower hard on the liver? +
The 1 fatal liver case in the reports involved a kava product. No liver failure from passionflower alone appears on PubMed.
Who should avoid passionflower? +
Anyone pregnant or breastfeeding, children, and anyone with surgery within 2 weeks. People on sedatives should ask first.
What not to mix with passion flower? +
Alcohol, benzodiazepines, sleeping pills, opioids and sedating herbs such as valerian or kava. Each adds to the same 1 effect.
What medications does passionflower interfere with? +
Mainly sedatives: benzodiazepines, sleeping pills, opioids and anesthesia. 1 case report involved lorazepam.
Is passion tea safe while pregnant? +
No. NCCIH says passionflower should not be used in pregnancy, and tea is no exception. The only human data covers 5 pregnancies.
Can I drink alcohol with passionflower? +
No. Both slow the nervous system, and our product label says the same. Avoid alcohol on the 1 evening you take it.
Can I drive after taking passionflower? +
Wait until you know how it affects you. Drowsiness is 1 of its 3 listed side effects.
Should I stop passionflower before surgery? +
Tell your surgeon or dentist. NCCIH advises talking to your provider if surgery is within 2 weeks.
Is passionflower safe for children? +
It has not been established. Our products are for adults, and a 2017 review of 9 ADHD trials in children rated its evidence as low.
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