A truth drug is a psychoactive substance that reduces inhibition in a subject, making it easier to obtain information in an interview. While popular fiction often has people providing detailed, accurate, and sensitive material readily after the administration of such compounds, the reality if this drug is somewhat more complicated. People can still exercise some self control and these medications may also cause hallucinations, leading the subject to mix up actual information with fantasies. Using these a truth drug in interrogation is generally not permissible under international law.
Truth drugs are often in the barbiturate class. People who have undergone anesthesia may be familiar with the effects of sedatives and hypnotics an anesthesiologist may use during presurgical preparation. They tend to reduce a state of euphoria and people have trouble being selective about what they talk about. Patients getting ready for anesthesia may babble or talk nonsense, and sometimes reveal personal or compromising information by accident. They may or may not respond to questions, depending on the level of sedation and the drug.
Research to uncover a reliable truth drug reached its height in the 1950s. Many governments wanted a magic bullet for interrogations to allow them to bypass training and conditioning and force people to reveal information. Ultimately, the conclusion was that a highly reliable drug would be impossible to develop, although compounds like scopalamine, sodium amytal, and thiopentene sodium are sometimes used as truth drugs.
There are valid medical uses for a truth drug. These drugs can be used to induce sedation before anesthesia to make patients more comfortable, with the volubility of some patients being a side effect. Psychiatric practitioners may use small amounts of these medications with their patients in controlled settings. This can sometimes be helpful for achieving therapeutic breakthroughs or collecting information to assist with the development of a diagnosis.
Much to the dismay of spy novel fans, no drug can open someone's mind totally. Interrogators can use a variety of techniques to try to extract information, but the unreliability of truth drugs makes them a less than ideal choice, legal and ethical issues aside. Subjects may blur fact and fiction, mix up information from books, films, and other sources, or report on their hallucinations. There is also a possibility of having a bad reaction to a truth drug. In an environment where medical support is not available, someone could go into anaphylactic shock or cardiac arrest, and die before bystanders can find a doctor to provide treatment.