As ketamine treatment grows more popular, many people are turning to this medicine as an alternative to daily medications. In fact, ketamine is now one of the safest and most effective alternatives to antidepressants, and people are beginning to take notice. It’s also commonly used in combination with psychotherapy, known as ketamine assisted therapy, as it can help individuals make breakthroughs and get more out of a therapy session.

Ketamine is now commonly being advertised as a method of “psychedelic” therapy, which raises the question: is ketamine a psychedelic? Isn’t it a little different from drugs like LSD and psilocybin?

To cut right to the chase, the answers are yes, and yes. We’ll get into why in a minute. 

Why does it matter if ketamine is a psychedelic?

In the scientific world, whether or not ketamine is officially considered a psychedelic is more or less a matter of semantics. However, we think recognizing ketamine as a psychedelic is much more important than that. 

Ketamine’s classification as a psychedelic has implications for our attitudes toward psychedelic therapy and its accessibility. Acknowledging the psychedelic characteristics of ketamine helps us to understand how and why psychedelic therapy works, and allows us to better utilize it to help people overcome mental illness. 

In the United States, the mental health crisis is the second leading public health crisis, impacting about 21% of the adult population. Psychedelic medicine research is having positive results for conditions like depression, bipolar disorder, anxiety disorders, PTSD, and more. Rather than nit-picking the differences between ketamine and other psychedelic substances, it’s more productive to focus on accessibility of psychedelic medicine for those who need it. 

What defines a psychedelic experience?

The term “psychedelic” was first coined by English psychiatrist Humphrey Osmond, in a letter addressed to Aldous Huxley in the 1950s. It’s a combination of the Greek words psyche, which means “mind”, and delos, meaning “to reveal”. At its very core, a psychedelic experience is a manifestation of the mind, which naturally lays way for its potential for introspection and learning. 

There are many key characteristics that come to mind when we think of a psychedelic experience, and these aren’t just stereotypes. Experiences on psychedelics have a few hallmarks that are shared by just about everyone, although the individual nature of a psychedelic experience can vary widely. Most often, individuals will gain some sort of insight or new emotions about themselves, how they relate to others and the world, and may be able to identify and analyze patterns of behavior or thought in meaningful ways. 

• Novel insights: New experiences, emotions, revelations, and connections that were not previously known or understood. 
• Timelessness: The experience feels as though it is taking place outside of time, or time becomes highly distorted, typically lengthened.
• Ineffability: The experience is difficult or impossible to adequately describe in words. Linear language does not seem to describe the fullness of the experience. 
• Ego dissolution: The dissipation of the sense of being an isolated, separate self. 
• 3rd person perspective: A sense of looking back at yourself or your psyche from a detached, observational position. This perspective helps induce novel insights, emotions, or understandings about oneself.
• Higher-order reality: A sense of seeing a “true” reality or a higher order reality than what is commonly available in ordinary consciousness. 

These are the elements that help us define a psychedelic experience and make them so fundamentally powerful in a mental health context. Many opposers of ketamine as a psychedelic will point to specific physiological differences between ketamine and “classic” psychedelics, but we think that looking at these hallmarks helps to better identify what is important about a psychedelic experience. 

Ketamine as a Psychedelic

Ketamine treatment reliably and effectively produces many or all of the classic indicators of a psychedelic experience within a single session. Individuals commonly report a distorted sense of time, find their experiences difficult to describe, feel detached from their self (dissociation), and feel as if they were able to access a new, yet familiar, space with novel realizations and information. 

Ketamine also has neurobiological similarities with other psychedelics like psilocybin and LSD. They aren’t exactly the same, however. The mechanism of action for LSD and psilocybin mainly lies in the serotonin system, acting on 5HT2A and other receptors. 

Ketamine’s effects on the brain focus on an entirely different system of neurotransmitters: the glutamate system. More specifically, ketamine is an NMDA-receptor antagonist, which leads to a surge of glutamate in the brain (note that glutamate is the most abundant excitatory neurotransmitter in the brain). Many who argue against ketamine as a psychedelic quote this reason. However, while ketamine may have a different mechanism of action within the brain, the neurological outcomes are still similar. More specifically, recent research from Johns Hopkins University has given us an updated classification system for psychedelics.

It turns out that the primary mechanism of psychedelics is not activating the serotonin 5HT2A receptor. Instead, psychedelics that activate the 5HT2A receptor can be more accurately classified as hallucinogenic psychedelics. People may also refer to hallucinogenic psychedelics as “classical” psychedelics, which is not particularly historically accurate given the use of non-hallucinogenic psychedelics throughout human history. Psychedelics such as MDMA can be more accurately classified as empathogenic psychedelics, psychedelics such as ibogaine can be more accurately classified as oneirogenic psychedelics, and psychedelics such as ketamine can be more accurately classified as dissociative psychedelics.

The universal mechanism behind all of these sub-categories of psychedelics is not the initial neurotransmitters that they modulate, but rather what happens afterwards. Each psychedelic has a unique characteristic that allows for special critical periods in the brain to open. Critical periods are special time periods in human development that allow for us to rapidly learn new information that helps us in our environment. For example, there is a critical period for language in childhood, and if a child is not exposed to language by the time the critical period closes, they will be unable to have full command of language when they are an adult.

Psychedelics like ketamine can open critical periods that are usually closed. They do this by modulating a pathway involving increasing neuroplasticity in the brain, which then “opens” that critical period and allows for the brain to temporarily be extraordinarily receptive to new ways of thinking, feeling, and processing information about the world and oneself. This is thought to be one of the main therapeutic mechanisms for psychedelics. Ketamine in particular can also reduce activity in the Default Mode Network, which is notable in that this network is overactive and unable to be turned off in individuals with Major Depressive Disorder.

We conclude that ketamine should certainly be considered a psychedelic, as it can produce all the hallmarks of a psychedelic experience and has all the same positive impacts on individuals in a mental health context. Although there may be neurological differences between ketamine and psychedelics like LSD, ketamine is a psychedelic in the ways that matter.