The quest for a perfect “truth serum” has spanned decades. The Central Intelligence Agency (CIA) has been particularly interested in exploring different drugs that show potential as truth drugs; MDMA and Thiopental have been of particular interest. This article uncovers the history behind the different types of truth drugs and whether or not any of them actually work. 

What Is a Truth Serum?

Truth serum is a colloquial name that defines a range of hallucinogenic compounds that can be used to obtain valid information from subjects without their consent.

The History of Truth Drugs

The search for a truth drug goes thousands of years back, to the days of the Roman historian Cornelius Tacitus. Tacitus believed that Germanic tribes used alcohol as a truth serum during council meetings. Alcohol is believed to suppress higher centers that control one’s thought process. This reduces one’s inhibitions and makes it harder for one to conjure up a lie. This also forms the basis for the trite phrase “in vino veritas,” which means truth in wine. Others may say drunks don’t lie. 

Mescaline derivatives”, including MDMA, have been researched by the United States (U.S.) military since the late 1940s to assess their potential as “truth serums.”

Scopolamine was among the first drugs to gain popularity as a “truth serum.” This is after American physician Robert House, after successful delivery, asked a mother about the whereabouts of the baby scale. Being in a scopolamine-induced twilight state of consciousness, the mother gave accurate instructions on where the scale could be found.

Dr. Robert House conducted further experiments that revealed that individuals could not withhold secrets in a scopolamine-induced state since they had no imagination capacity to create a lie. He imagined different applications for such a drug, especially in unraveling crime.

This began a long quest to investigate the use of psychedelics as a truth serum by the CIA.

Nazi Research on Truth Drugs

The use of mescaline as a truth drug goes back to the 1940S. British intelligence intercepted telecommunication from a town in Ukraine (Schutzstaffel (S.S.)-Führer of Dnjepropetrowsk) that was received on July 24th, 1942. This communication was requesting for the delivery of 50 grams of mescaline which was to be used for interrogation that was going on at the medical headquarters in Berlin. 

Since 1943, German physicians working in concentration camps in Dachau and Auschwitz investigated the potential of different hallucinogens, barbiturates, morphine derivatives, and mescaline as truth drugs for interrogation purposes. A prisoner nurse involved in the study noted that the aim of using these compounds was “to eliminate the will of the person examined.”

The research involved thirty inmates who were each offered different hallucinogens (mescaline, barbiturates, scopolamine). According to the camp physician Dr Kurt Plötner, the “best results” were obtained when the inmates were offered mescaline together with coffee. While some prisoners got furious, others became melancholic and withdrawn. 

However, in every case, the examiner drew out even the most intimate secrets from the inmates. But despite the apparent success, Plötner concluded that mescaline was “too unreliable” to be used as a truth drug.

Truth Serum Research by the US Military Beginning in the 1940s

Further research by the US military revealed that cannabis Indica has promising potential that warrants further experiments. The researchers highlighted criteria for choosing an ideal compound that could be used as a truth drug:

  • Ability to be offered without the knowledge of the subject
  • Ability to induce a talkative uninhibited mood
  • It should not be addictive or psychologically harmful
  • It should not cause suspicion in the subject

The Central Intelligence Agency (CIA) Research on Truth Drugs: 1940s to 1960s

The CIA has been interested in investigating the potential of “truth drugs'' since early in the 1940s. In 1949, the famous Hungarian Cardinal Mindszenty was arrested and put on trial for his open opposition to the Communist regime. 

During the trial, it was clear that he was under some “behavior manipulation.” He appeared to be absent-minded and even exhibited “robotic movements.” He went further to confess to crimes that he had never committed. This caused the CIA to believe that he was under the influence of a hallucinogen.

Immediately after the trial, Allen Dulles, then Deputy Director of the CIA, gave directions to investigate Russian interrogation practices. Consequently, U.S. military research on mind control and manipulation intensified. 

Project BLUEBIRD, Project ARTICHOKE and Project MKUltra

A similar incident happened in 1950 when U.S. prisoners of war captured in Korea were manipulated into confessing that the U.S. had used biological weapons in Korea. It became a priority for the U.S. to learn more about these techniques used during interrogation. In the same year, the CIA director Roscoe Hillenkoetter implemented Project BLUEBIRD to discover means used to condition personnel to prevent manipulation from extracting information from them unknowingly. This project was later renamed Project ARTICHOKE

This project was created by the CIA to research the effectiveness of interrogation methods such as the use of truth serums. It also investigated the use of hypnosis as an investigative tool. It led to the creation of the infamous Project MKUltra in 1953. 

This project allegedly involved a series of “illegal experiments” conducted on human subjects to investigate the effectiveness of psychedelics as interrogation tools. The scope was very broad, involving about 80 institutions (colleges, universities, prisons, hospitals, and pharmaceutical companies). These drugs were used to weaken one’s resolve and consequently force confessions from subjects. This is referred to as “pharmacological torture.”

What Drug Works Best as a Truth Serum?

The CIA has focused most of its attention on three popular psychedelics: scopolamine, mescaline, and LSD. As much as these compounds have shown a lot of promise, they have failed to deliver on the expectations of the CIA. Some inherent weaknesses in these compounds compromise their reliability as truth serums, as you will learn below.

Mescaline as a Truth Serum

At the start of the twentieth century, a German psychiatrist Kurt Beringer began investigating mescaline inebriation and its potential as a truth drug. In 1931, he published a report with the title Confessions during mescaline inebriation. This report revealed how mescaline was able to reduce inhibitions, and this led to unbridled confessions. This report was later published by the Italian psychoanalyst Baroni. It was suggested that the military could use this to extract information from uncooperative subjects. In 1943, mescaline was discarded as a truth drug because it produced hallucinations that got in the way of extracting reliable information from subjects.

Scopolamine as a Truth Serum

Research on truth drugs such as scopolamine started in the early 1920s. Initially, this happened by chance and was not the result of goal-directed research. Scopolamine was later discarded since it triggered a state of delirium with disorientation, confusion, and a parched mouth, which made it hard for the subjects to talk. 

Barbiturates as Truth Serums

Barbiturates are a class of sedatives that have also been used as truth serums. They are classified according to the duration of their action. 

Sodium Thiopental

Sodium Thiopental, also known as Sodium Pentothal, Thiopental, Trapanal, or thiopentone is a fast-acting barbiturate whose actions kick in within 20 minutes after it has been administered. In India, it is still in use in courts that allow narco analysis for high-profile cases. In 2007, an affluent businessman, Moninder Singh Pandher, and his servant were injected with this drug, and they confessed to serial murder charges. One BBC reporter voluntarily took this drug to study its effects as a truth serum. He reported that as much as he was more inclined to talk, most of what he said was merely wishful thinking and only had a grain of reality. It has also been used by psychiatrists to get patients to talk about painful repressed memories. 

Sodium Amytal / Amobarbital

Sodium Amytal, also known as Amobarbital or Amylobarbitone has also been used as a truth serum. IN 1931, this drug was offered to a murder suspect by the name of John Whalen. His testimony under the influence of the drug led to his release. This led to the use of “barbiturate interviews” as admissible evidence in some cases. However, it was observed that most subjects were inclined to say what the interviewer needed to hear and not the truth, especially if the subject was guilty. In 1963, the use of sodium amytal as a truth serum was halted by the CIA under the guise that this amounted to torture.

Unfortunately, barbiturates have presented a challenge of certainty in the information that is generated. The lack of certainty invalidated their use as truth serums. 

LSD as a Truth Serum

LSD was tested on a military officer in 1952. The officer had been instructed not to reveal a military secret. After being given LSD, he revealed all the details he had been asked not to. This was quite promising, and consequently, LSD was used for some years as a truth drug by the military. However, it fell out of favor after it was discovered that it also caused excessive hallucinations. This interfered with the validity of the extracted information, and LSD was halted in 1966. 

MDMA as a Truth Serum

The military then moved to mescaline-like compounds that would produce similar (truth) effects but minimal counterproductive effects. These compounds would produce “pure” euphoria without causing a subsequent let-down. 

From the CIA reports, the ideal drug for interrogation should lower conscious ego control sufficiently to facilitate the recall of suppressed material and make it difficult to withhold information. At the same time, it should not interfere with cognitive abilities. 

MDMA, which stands for methylenedioxy-methylamphetamine, is a mescaline-like compound. Compared to LSD and mescaline, MDMA provides a useful starting point for a more reliable truth serum that the CIA can effectively use. MDMA can induce “pure’ euphoria without interfering significantly with cognition and sensory perception. 

Therefore, the benefit of MDMA is that while the subjects maintained intact cognition, they were vulnerable and cooperative. However, it remains unclear to this day whether the CIA used any mescaline derivative that was tested operationally.

Polygraph Vs. Truth Serum

A polygraph is a special instrument that is used to measure a person’s physiological characteristics such as pulse and breathing rate to determine if they are lying. It is also called a lie detector test. Unlike a truth serum, a polygraph is less subjective and is therefore likely to give results with a higher degree of accuracy. 


Over the years, the CIA has investigated the potential of several drugs as truth serums. Most of these drugs have limited effectiveness and may provide inaccurate information. Because validity is never guaranteed, the use of truth serums as interrogation tools (narcoanalysis) has gradually fallen out of favor. As much as barbiturates have been used recently (2007) in India in some top-profile cases, the Indian Supreme Court considers their use illegal. 

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