Catnip, or Nepeta cataria, is a perennial herb in the mint family well-known for its striking behavioral effects on domestic cats and many other felids. When a feline encounters the plant, it often results in a flurry of rolling, rubbing, and general euphoria that lasts for a short time. This temporary state of excitement raises a common question: if it affects cats so profoundly, why are humans completely unaffected? The answer lies in the specific biological differences between the feline and human sensory and neurological systems.
Nepetalactone: The Active Compound
The substance responsible for the cat’s intense reaction is a volatile compound called nepetalactone. This chemical is categorized as an iridoid, a type of monoterpene that plants often use for defense against insects. Nepetalactone is concentrated within microscopic glands, or bulbs, found primarily on the leaves and stems of the Nepeta cataria plant.
When the plant material is bruised, crushed, or chewed, these tiny bulbs rupture, immediately releasing the volatile oil into the air. Nepetalactone and its various isomers make up a significant portion of the essential oil distilled from catnip, triggering the unique feline response.
The Feline Sensory and Brain Response
The catnip-induced behavior begins not with ingestion, but with inhalation, as nepetalactone must enter the cat’s nasal passages. Once inhaled, the molecules bind to specialized sensory receptors in the nasal tissues, which are highly sensitive to this specific chemical structure. The effect is potent because the structure of nepetalactone closely mimics a feline pheromone.
This binding stimulates sensory neurons that send electrical impulses to the brain, specifically targeting the olfactory bulb. From the olfactory bulb, the signal travels rapidly to two distinct regions: the amygdala, which processes emotional responses, and the hypothalamus, which regulates behavioral and sexual responses. This neural cascade activates the cat’s opioid system, resulting in temporary euphoria and characteristic behaviors like rolling and rubbing. This sensitivity is a genetic trait, and about 20 to 30% of domestic cats lack the inherited response entirely.
Why Humans Do Not Share the Effect
Humans do not experience the same psychoactive effects from catnip because we lack the necessary biological mechanism. The primary reason is the absence of the specific, highly sensitive olfactory receptors in the human nasal and olfactory systems that are present in cats. While humans can detect the compound’s aroma, our olfactory wiring does not translate this chemical signal into the powerful neural cascade seen in felines.
The human olfactory bulb and subsequent neural pathways do not process nepetalactone as an internal pheromone mimic. In a cat, the chemical bypasses typical sensory processing to directly influence the brain’s pleasure and behavioral centers. Conversely, the human brain’s structure and receptor profile are not equipped to convert the nepetalactone signal into a euphoric response. This physiological difference is why the plant only affects cats.
Catnip Uses Beyond the Feline High
Although catnip does not cause a euphoric response in humans, the plant has been used for centuries in herbal applications. When consumed as a tea, catnip has mild sedative properties that can aid in relaxation and promote sleep. This calming effect is attributed to other compounds found in the plant, not the nepetalactone that affects cats.
Historically, people have used catnip to alleviate symptoms of colic, digestive discomfort, and nervousness. Beyond internal uses, the plant’s essential oil, which contains nepetalactone, acts as an effective insect repellent against various pests, including mosquitoes. These human applications rely on different chemical constituents of the herb or physiological mechanisms separate from the neurological process in the cat.