A single dose before a stressful event calms about as much as a standard sedative drug, while leaving coordination, reaction speed and memory of the event intact. Measured sleep lengthens modestly. Benefit for long-standing anxiety is unsettled. It adds to anything else that sedates, and most tested supplements did not contain what their labels claimed. (Full Review)

Protocol

Standard European dry-extract protocol

200–800 mg dry extract daily

Or 0.5–2 g dried herb infused as tea up to three times daily. Most practitioners start at 250–400 mg.

Situational single-dose protocol

260–500 mg single dose

Taken 30–90 minutes before an anticipated stressor; the regimen used in surgical and dental trials.

Best time of day

Evening

Evening for the sleep and daily-calm goal, 30–90 minutes before the event for the situational goal. Daytime dosing is where sedation complaints concentrate.

Time to effect

Situational anxiety

30–90 minutes

Response to a single dose.

Sleep and daily calm

1–2 weeks

30-day trials showed further gain.

Minimum useful trial period

2 weeks

Set by the one-to-two-week window in which sleep and daily-calm effects were measured.

Benefits

High: Reduction of acute situational anxiety

Medium: Improved sleep quality and total sleep time; sustained reduction in generalized anxiety; calming effect without psychomotor impairment or amnesia

Low: Support during benzodiazepine tapering; reduced mental symptoms of opioid withdrawal; lowered physiological stress markers

Speculative: Antioxidant and anti-inflammatory activity

Contraindications

Pregnancy at any gestational age, and breastfeeding

Congenital long-QT syndrome, QTc above 470 ms, or history of ventricular arrhythmia

Monoamine oxidase inhibitor use

Untreated moderate-to-severe obstructive sleep apnea (apnea-hypopnea index above 15 events per hour)

Decompensated liver disease (Child-Pugh Class C)

Prior hypersensitivity to Passiflora species or other Passifloraceae

Within 48 hours of driving-critical or safety-critical duty without a prior personal response test

Key Interactions

Benzodiazepines and Z-drugs: diazepam, alprazolam, lorazepam, oxazepam, zolpidem, zaleplon, eszopiclone

Opioids: oxycodone, morphine, tramadol, buprenorphine

General anesthetics and pre-medication

Sedating over-the-counter medicines: diphenhydramine, doxylamine, chlorpheniramine, "PM" analgesic combinations

Alcohol

Warfarin and antiplatelet agents

CYP3A4 substrates: simvastatin, atorvastatin, tacrolimus, ciclosporin, apixaban

Sedative supplements: valerian, kava, hops, lemon balm, chamomile, melatonin, magnesium glycinate, L-Theanine, cannabidiol

Antihypertensives and blood-pressure-lowering supplements

Risk & Side Effects

High: Drowsiness and daytime sedation

Medium: Potentiation of sedative and anti-anxiety drugs; substandard, misidentified or adulterated products

Low: Nausea, vomiting and dizziness at labeled doses; QT prolongation and non-sustained ventricular tachycardia; hypersensitivity vasculitis; adverse outcomes in pregnancy

Speculative: Reduced blood levels of CYP3A4-metabolized drugs

Monitoring

Marker	Target	Why
QTc interval	Under 430 ms (men), under 440 ms (women)	Screens the one serious cardiac signal reported
Serum potassium	4.2–4.6 mmol/L	Low potassium lengthens repolarization independently
Serum magnesium (red blood cell)	5.0–6.5 mg/dL	Low magnesium compounds any repolarization effect
ALT	10–26 U/L (men), 10–19 U/L (women)	Confirms no unexpected liver effect from a multi-herb product
Insomnia Severity Index	Under 8	The primary success measure for the sleep goal
GAD-7 anxiety score	4 or below	The primary success measure for the anxiety goal
Sleep efficiency	88–92%	Tracks the objective sleep endpoint that moved in trial

Cadence: Symptom scores at 2 weeks and 4 weeks, then every 3 months while use continues. Electrocardiogram repeated only if the dose rises or a QT-prolonging drug is added; liver enzymes rechecked annually.

Qualitative Assessment

Morning grogginess in the first hour after waking — the earliest sign the dose is too high or too late
Daytime alertness and reaction quality, particularly during driving or training
Ease of falling asleep, as distinct from total sleep time
Subjective evenness of mood under a known stressor, rather than at rest
Absence of memory gaps around the evening dose

Passionflower for Health & Longevity

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment