Psychedelic vs. Hallucinogen-What’s in a Name?

It’s not merely the drugs themselves that have gone mainstream, it’s also their names: psilocybin, ayahuasca, peyote, ketamine, DMT. Ten years ago, few if any of these terms would have been familiar to the average Netflix viewer or Reddit scroller. Today, they’re seemingly everywhere.

But how to explain the diverging fortunes of two words often used interchangeably to describe the entire class? While “psychedelic” has gained the greatest currency of all in recent years, “hallucinogen” hasn’t kept up — and appears to be losing value.

A quick way to gauge the relative popularity of the two words is to use a basic Google search. “Psychedelic” generates about 102 million results across the Web, while “hallucinogen” turns up a mere 6.2 million. Using Google Scholar, which offers a more specialized view of the terms’ use in published and unpublished literature from a range of disciplines, the difference remains — though not as stark: 75,400 results for “psychedelic” versus 26,800 for “hallucinogen.” 

A third comparison comes courtesy of PubMed, the National Institutes of Health’s (NIH) database of more than 32 million articles published in biomedical journals. In this purely scientific context, the two terms are on nearly equal footing: since 1946, “hallucinogen” has been used in 27,608 articles, and “psychedelic” in 27,453. A combined search for scientific articles employing both terms turns up 26,916 results, indicating they’ve typically been used together, perhaps without much distinction.

Yet those totals obscure an interesting trend from the last few years: “psychedelic” looks to be gaining ground — and quickly. Through 2017, the first 71 years of the PubMed database, “hallucinogen” appeared in 309 more articles than “psychedelic,” an average of 4.4 more articles per year. From the beginning of 2018 through today, however, their fortunes have reversed, with “psychedelic” taking the lead by a difference of 160 articles or 49.2 per year.

One can draw a few conclusions from these data points. Across all types of online media and content, “psychedelic” is indeed far more popular than “hallucinogen.” But the more academic or scientific the source, the more likely “hallucinogen” is to be used. Finally, in recent years “hallucinogen” has begun fading from use within its traditional stronghold, the scientific literature. 

But why? What explains these patterns and trends? Culture, tradition, politics, fear, and etymology (the origin and development of words) all come into play, argues psychedelic researcher and University of North Carolina professor Dave Nichols early in his exhaustive 2016 review article Psychedelics.¹ 

The second sentence of this nearly hundred-page article begins, “When I began my graduate studies in 1969, it was politically correct in scientific circles to refer to these substances only as psychotomimetics, a negative term suggesting that they fostered a mental state resembling psychosis.”

Nichols continues, “Later, as it was realized that these compounds did not provide very realistic models of psychosis or mental illness, it became more correct to refer to them as hallucinogens, again a pejorative term suggesting that they principally produce hallucinations. Yet that is not what they do in most users at ordinary doses, so this term likewise is not particularly descriptive or useful, although it is still widely used and seems to remain the preferred name for these substances in most scientific writing.”

Finally, another paragraph down, Nichols discusses his preferred alternative. “The name ‘psychedelics’ for these substances was coined by Humphry Osmond in 1957, connoting that they have a mind-manifesting capability, revealing useful or beneficial properties of the mind,” he writes. “This name has been popular among the lay public for more than 5 decades, but it has generally been frowned upon by the scientific community because it implies that these substances have useful properties.” 

Nichols’ observation in 2016 that “hallucinogen” is often pejorative while “psychedelics” is more complimentary seems particularly astute in light of what’s been happening in our culture and scientific literature since then. As awareness of the beneficial effects of psychedelics has exploded, so too has the use of the term “psychedelic.” 

Likewise, just as researchers are increasingly acknowledging and exploring the myriad manifestations and potential health benefits of psychedelics, they are also learning just how inadequate the term “hallucinogen” can be, not to mention misleading.

Still, at least one defender of the term can be found in none other than Terence McKenna, the late psychonaut, ethnobotanist, and evangelist whose ideas still reverberate through the psychedelic sphere. For him, and for many of his adherents — not to mention, likely, for the majority of users of vision-inducing drugs across cultures and throughout human history — hallucination is the central, if not defining aspect of the experience. 

McKenna saw hallucination not as an illusion, but rather as a window to something real. “A hallucination is to be in the presence of that which previously could not be imagined, and if it previously could not be imagined then there are no grounds for believing that you generated it out of yourself,” McKenna once said. He also, for good measure, titled his 1998 memoir True Hallucinations.

In this sense, both words have their place. The key, it seems, is using them accurately and intentionally.

Nate Seltenrich

Nate Seltenrich is a Bay Area-based independent science journalist covering a wide range of topics including psychedelic and cannabinoid science, environmental health, climate change, and more. His work has appeared in many international, national, regional, and local magazines, newspapers, and websites.

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