Marijuana has historically been classified as a hallucinogen by scientists, but this label is misleading. Cannabis doesn’t fit neatly into any single drug category. It can produce depressant, stimulant, and hallucinogenic effects depending on the dose, the strain, and the person using it. At typical doses, the hallucinogenic effects are mild or absent. At high doses, perceptual distortions can occur, but they’re qualitatively different from the hallucinations caused by drugs like LSD or psilocybin.
How Cannabis Is Officially Classified
Under the U.S. Controlled Substances Act, marijuana is a Schedule I substance. That classification means the federal government considers it to have a high potential for abuse and no currently accepted medical use. Schedule I doesn’t distinguish between hallucinogens, stimulants, or depressants. LSD, heroin, and MDMA all sit in the same schedule despite working very differently in the brain.
The DEA’s drug fact sheets and the World Health Organization both identify THC (delta-9-tetrahydrocannabinol) as the principal psychoactive compound in cannabis. CBD, the other well-known compound, is not psychoactive. The WHO notes that the main adverse effects of cannabis use are dizziness, impaired motor control, and impaired cognitive function, which are effects more associated with depressants than with hallucinogens.
Why Scientists Called It a Hallucinogen
The hallucinogen label dates back decades and stuck partly because cannabis can, at high doses, alter perception. People may experience visual distortions, heightened sensitivity to sound, or a sense that time is moving differently. In clinical settings, diagnostic criteria for cannabis intoxication include the possibility of hallucinations and delusions as features of severe reactions. These effects gave scientists enough reason to group cannabis alongside other perception-altering drugs.
But “can cause hallucinations in some people at high doses” is very different from “is a hallucinogen.” Plenty of drugs that aren’t classified as hallucinogens can trigger perceptual disturbances at extreme doses or in vulnerable individuals. The hallucinogen label for cannabis reflects an older, less nuanced approach to drug classification.
How Cannabis Effects Differ From True Hallucinogens
Classic hallucinogens like LSD, psilocybin (the compound in magic mushrooms), and mescaline all work by activating a specific serotonin receptor in the brain called 5-HT2A. There’s a strong, well-documented correlation between a drug’s potency at this receptor and the intensity of its hallucinogenic effects. THC doesn’t work this way. It binds to cannabinoid receptors, which are part of a completely separate signaling system. Studies have confirmed there’s no cross-tolerance between THC and LSD, meaning tolerance to one doesn’t reduce the effects of the other. This is strong pharmacological evidence that the two drugs act through different mechanisms.
The subjective experience also differs. In a case study comparing cannabis-induced perceptual changes to those from psilocybin and DXM (an atypical hallucinogen), researchers documented a person who experienced visual distortions, auditory hypersensitivity, and an out-of-body sensation after a high dose of THC. He saw patterns moving on carpet and chairs, felt the floor sinking away, and described feeling removed from his body. These sound hallucinogenic on the surface. But when scored on standardized scales, his experience showed significantly lower changes in affect and cognition compared to psilocybin and DXM. Since shifts in emotion and thought patterns are core features of a classic hallucinogenic experience, the researchers concluded that what cannabis produces is something pharmacologically distinct.
A 2023 review of the literature reinforced this view, finding that cannabis has “largely not been regarded as having psychedelic effects in contemporary literature,” even though it has a long history of being used alongside classic psychedelics to achieve altered states of consciousness.
What Cannabis Actually Does to Perception
At typical recreational doses, cannabis produces relaxation, euphoria, increased appetite, altered sense of time, and sometimes mild sensory enhancement. Colors might seem more vivid, music more engaging, food more flavorful. These are perceptual shifts, but they fall well short of hallucinations.
At high doses, things can intensify. The case study mentioned above provides a useful snapshot: the person reported hypersensitivity to voices around him, though he couldn’t make out distinct words. He saw visual distortions rather than fully formed images that weren’t there. He felt paralysis and a dissociative, out-of-body state. These experiences are real and can be distressing, but they’re better described as perceptual distortions than true hallucinations. You’re not seeing things that aren’t there so much as seeing real things in a distorted way.
The distinction matters because true hallucinations, where a person perceives something with no external stimulus at all, are rare with cannabis alone. When they do occur, they tend to happen in people using very high doses or in those with a predisposition to psychotic symptoms.
Cannabis and Lasting Perceptual Changes
There is one area where cannabis overlaps with hallucinogens in a clinically meaningful way. Hallucinogen-persisting perception disorder (HPPD) is a condition where perceptual disturbances continue long after a drug has left the body. It’s most commonly associated with LSD, but cannabis has been linked to HPPD as well, particularly in people who also use other hallucinogens. Type II HPPD can cause chronic, distressing visual disturbances that persist for months or even years, waxing and waning in severity. Most documented cases involve polysubstance use rather than cannabis alone.
A Drug That Defies Simple Categories
The most accurate way to think about cannabis is as a drug that crosses multiple pharmacological categories. It slows reaction time and promotes relaxation like a depressant. It can increase heart rate and alertness like a stimulant. It can distort perception like a hallucinogen. No single label captures what it does, which is why many pharmacologists now treat cannabis as its own category rather than forcing it into one of the traditional three.
So while calling marijuana a hallucinogen isn’t entirely wrong, it overstates one possible effect and ignores the broader picture. The hallucinogenic potential is real but dose-dependent, relatively uncommon, and pharmacologically different from what classic hallucinogens produce.