Truth Serum

Truth Serum


Truth serum is a term given to any of a number of different sedative or hypnotic drugs that are used to induce a person to tell the truth. Truth serums cause a person to become uninhibited and talkative, but they do not guarantee the veracity of the subject.

In 1943, J. Stephen Horsley published a book in which he described the psychotherapeutic method of narcoanalysis. By chance, he observed that persons who were under the influence of narcotics were uninhibited, talkative, and answered all questions that were asked of them. A narcotic is a drug that dulls the senses, relieves pain, and induces sleep. Persons who were under the influence of narcotics entered a hypnotic-like state and spoke freely about anxieties or painful memories. Once the drug effect had worn off, the person had no recollection of what he or she said. Horseley coined the term "narcoanalysis." Narcoanalysis has since been used to assist in the diagnosis of several different psychiatric conditions.

The term "truth serum" has been applied to drugs that are used in narcoanalysis. This term is a misnomer in two ways: the drugs used are not serums and truthfulness is not guaranteed. Although inhibitions are generally reduced, persons under the influence of truth serums are still able to lie and even tend to fantasize. Courts have ruled that information obtained from narcoanalysis is inadmissible.

Narcoanalysis is not used in the United States as an interrogation method. The Federal Bureau of Investigation (FBI) and other federal law enforcement agencies object to the use of truth drugs, preferring instead to use psychological methods to extract information from suspects or prisoners. The United Nations considers the use of truth drugs to be physical abuse and, therefore, a form of torture. The issue was revisited in 2002, when some authorities, including former Central Intelligence Agency and FBI chief William Webster, frustrated by the lack of forthcoming information from suspected al-Qaeda and Taliban members held at the U.S. prison in Guantanamo Bay, Cuba, advocated administering narcoanalysis drugs to uncooperative captives. United States Secretary of Defense Donald Rumsfeld asserted that narcoanalysis is not used by United States military and intelligence personnel, but suggested that other countries have made use of the technique in the interrogation of suspected terrorists.

Drugs used as truth serums. Two of the most commonly used truth serums are members of the barbiturate drug class. Barbiturates are sedatives and hypnotics that are created from barbituric acid. They are divided into classes according to the duration of sedation: ultrashort, short, intermediate, and long. Ultrashort-acting barbiturates are used as anesthetics whereas long-acting ones are used to treat convulsions (anticonvulsive). Barbiturates are controlled substances due to their high potential for abuse and for addictive behavior.

Sodium pentothal (pentothal sodium, thiopental, thiopentone) is an ultrashort-acting barbiturate, meaning that sedation only lasts for a few minutes. Sodium pentothal slows down the heart rate, lowers blood pressure, and slows down (depresses) the brain and spinal cord (central nervous system) activity. Sedation occurs in less than one minute after injection. It is used as a general anesthetic for procedures of short duration, for induction of anesthesia given before other anesthetic drugs, as a supplement to regional anesthesia (such as a spinal block), as an anticonvulsive, and for narcoanalysis.

Sodium amytal (amobarbital, amylobarbitone, Amytal) is an intermediate-acting barbiturate. Sedation occurs in one hour or longer and lasts for 10 to 12 hours. Sodium amytal depresses the central nervous system. It is used as a sedative, hypnotic, and anticonvulsive and for narcoanalysis. When sodium amytal is used for narcoanalysis it may be called an "Amytal interview."

Scopolamine (hyoscine) is an anticholinergic alkaloid drug that is obtained from certain plants. Anticholinergic drugs block the impulses that pass through certain nerves. Scopolamine affects the autonomic nervous system and is used as a sedative, to prevent motion sickness, to treat eye lens muscle paralysis (cycloplegic), and to dilate the pupil (mydriatic).



Horsley, J. Stephen. Narco-Analysis. A New Technique in Short-Cut Psychotherapy: A Comparison with Other Methods and Notes on the Barbiturates. New York: Oxford University Press, 1943.


Johnson, K. and R. Willing. "Ex-CIA Chief Revitalizes 'Truth Serum' Debate." USA Today. (April 26, 2002): 12a.

Romanko, J.R."Truth Extraction." New York Times Magazine. (November 19, 2000): 54.



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