The History of Ketamine: From Battlefield Anesthetic to Mental Health Breakthrough

Few drugs in medical history have traveled as unexpected a path as ketamine. Synthesized in a laboratory over 60 years ago as a safer alternative to an anesthetic that caused hallucinations, it went on to serve soldiers on the battlefields of Vietnam, become one of the most abused club drugs of the 1990s, and then — in one of medicine's great reversals — emerge as arguably the most significant advance in depression treatment in half a century. Here's the full story.

1962: Birth of a Molecule

Ketamine was first synthesized in 1962 by Dr. Calvin Stevens at Parke-Davis pharmaceutical company (now part of Pfizer), working under a contract with the University of Michigan. Stevens was searching for a safer successor to phencyclidine (PCP), a powerful anesthetic that had been abandoned due to its severe and prolonged hallucinogenic side effects and its tendency to cause what clinicians called "emergence delirium" — intense agitation upon waking.

Ketamine, chemically designated CI-581, produced similar anesthetic effects at lower doses but with a significantly shorter duration and a much more manageable emergence profile. In animal studies, it looked promising. Human trials began in 1964.

1964–1970: Human Trials and FDA Approval

The early human trials showed that subjects reported the expected dissociative effects — feelings of detachment, sensory distortion, dreamlike states — but recovered more quickly and safely than with PCP.

The FDA approved ketamine for human medical use in 1970, just in time for what would become one of its most consequential early applications.

1970s: Vietnam and the Battlefield Anesthetic

Ketamine's approval coincided almost exactly with the peak of American involvement in Vietnam, and it was rapidly adopted as a battlefield anesthetic by military medics. Its key advantages in combat settings: it could be administered intramuscularly without IV access, it maintained protective airway reflexes (unlike many anesthetics, patients continued breathing on their own), it provided rapid, titratable sedation and analgesia, and it was shelf-stable in field conditions.

American soldiers and their medical teams came to rely on it extensively. Its safety profile in austere environments cemented its place as an essential anesthetic and established the evidence base that would make it a global standard of care in emergency medicine, pediatric anesthesia, and settings with limited resources for decades to come.

1980s–1990s: The Emergence of a Controlled Substance

Ketamine's dissociative properties — the very features that made it effective as an anesthetic — also made it attractive as a recreational drug. By the late 1970s and 1980s, ketamine had found its way into the party scene, where it was called "Special K" and used for its intense, short-duration hallucinogenic effects.

The 1990s saw its widespread adoption in club culture. Reports of misuse, addiction, and bladder damage from chronic heavy use led the DEA to classify ketamine as a Schedule III controlled substance in 1999 — placing it in the same category as anabolic steroids and certain codeine combinations. This scheduling reflected abuse potential while acknowledging that ketamine had accepted medical uses — a classification it retains today.

2000: The Depression Discovery That Changed Everything

In 2000, a small but seismic study was published in Biological Psychiatry. Researchers at Yale University — led by Dr. John Krystal and Dr. Dennis Charney — administered a single sub-anesthetic dose of IV ketamine to patients with treatment-resistant depression and measured the results. The findings were startling: patients showed significant antidepressant effects within hours — sometimes within 2 hours — in stark contrast to the 4–6 weeks required for SSRIs to take effect.

For patients in severe, suicidal depressions who had tried multiple antidepressants without success, this represented something medicine had never offered before: rapid relief. The study was small and the research community was initially skeptical, but replication after replication confirmed the result. Ketamine worked for depression — fast, dramatically, and in patients for whom nothing else had.

2000s–2010s: From Research to Clinics

Through the 2000s, ketamine infusion clinics began opening across the United States, initially operating in a regulatory gray area. Anesthesiologists and psychiatrists began offering IV ketamine infusions off-label for treatment-resistant depression, PTSD, suicidality, and chronic pain. The evidence base grew rapidly, with dozens of clinical trials confirming the antidepressant, anti-suicidal, and analgesic effects of ketamine.

The mechanisms became clearer: ketamine's NMDA receptor blockade triggered a cascade of glutamatergic activity, BDNF release, and rapid synaptogenesis — rebuilding synaptic connections that had been lost to chronic stress and depression. This was a fundamentally different mechanism than any previous antidepressant.

2019: FDA Approves Spravato (Esketamine)

In March 2019, the FDA approved esketamine (Spravato) — the S-enantiomer of ketamine, administered as an intranasal spray — for treatment-resistant depression. This was the first genuinely new antidepressant mechanism approved by the FDA in over 30 years and the first ketamine-derivative approved for psychiatric use.

Spravato's approval validated decades of research and opened the door to broader insurance coverage and mainstream psychiatric adoption. However, it requires administration in a certified healthcare setting with monitored observation, limiting access for many patients.

2020s: The At-Home Era

The COVID-19 pandemic accelerated telehealth adoption across medicine — including mental health. The relaxation of in-person prescribing requirements enabled a new generation of ketamine providers to offer at-home sublingual ketamine therapy with remote medical supervision. What had been confined to IV infusion clinics and hospitals became accessible to patients in their own homes, at a fraction of the cost, while maintaining medical oversight through telehealth platforms.

This democratization has expanded access dramatically — reaching patients in rural areas, those with mobility limitations, people with severe anxiety who struggle with clinical environments, and those for whom cost had been the primary barrier.

The story isn't finished. Researchers are now studying ketamine for alcohol use disorder, PTSD, eating disorders, OCD, and more. A drug born in a 1960s pharmaceutical lab and tested on Vietnam battlefields has become one of the most versatile and important therapeutic tools in modern medicine.

If you'd like to explore whether at-home ketamine therapy is right for you, take our free 5-minute assessment to get started.