Mechanism of Action
Preclinical research proposes GABA-related activity: passion flower extracts appear to influence the brain's main inhibitory neurotransmitter system, the same broad system many calming agents act on. The compounds responsible have not been pinned down, so the mechanism is best described as proposed rather than established.
Evidence Summary
Passion flower's research base is the smallest in this formula, which is exactly why it plays a supporting role rather than a lead one. The most cited clinical result is a 2001 pilot double-blind randomised trial by Akhondzadeh and colleagues in the Journal of Clinical Pharmacy and Therapeutics, which compared passion flower extract with oxazepam, a benzodiazepine, in people with generalised anxiety. The extract performed comparably over the trial with less impairment of daily function, though the study was small and had no placebo arm. The US National Center for Complementary and Integrative Health sums up that human picture as suggestive but not definite.
In dogs, no controlled anxiety trial has been published. The only canine study verifiable as at August 2026 used a combination product containing passion flower in seven senior dogs and measured inflammation markers, not behaviour. A seven-dog combination study cannot show what passion flower alone does, so we treat it as context rather than proof.
In Petz Park Products
Stress + Anxiety for Dogs contains 50mg of passion flower per scoop, from $34.95 AUD for 45 scoops up to $99.95 AUD for 180, rated 4.7 stars from 590 reviews. Stress + Anxiety for Cats contains 10mg of passion flower extract per scoop, $32.95 AUD for 60 scoops or $58.95 AUD for 120, rated 4.7 stars from 235 reviews.
Safety and Considerations
Human references list drowsiness, dizziness and confusion as possible side effects and an additive effect with sedatives is expected. Passion flower should not be used in pregnancy because it may stimulate uterine contractions and the same caution applies to pregnant dogs. The dog formula also contains St John's Wort which interacts with many medications, so check with your vet if your dog takes any medication. If drowsiness is marked or your dog seems unsteady, stop and see your vet.