Truth Serums



""Wait, what the hell? This was supposed to be a truth serum, not a VOLUNTEER INFORMATION serum!""

- T-Rex, Dinosaur Comics

The common term "truth serum" refers to any number of sedative/hypnotic drugs which are used to induce honesty in a subject. In fact, truthfulness is not guaranteed by the use of such drugs; while a person under the influence of a truth serum may become talkative, or may experience reduced inhibitions or even hallucinogenic fantasies, they are still quite capable of lying. For this reason, and the obvious human and civil rights issues (which are similar to those regarding torture), any statements obtained in this manner are inadmissible in court. Or, they're really disgusting concoctions used in crossing the line ceremonies. The best that modern pharmacology can come up with is amobarbital (better known as sodium amytal) and is not all that useful at all.

Ah, but don't tell Hollywood that...

In movies and television, truth serums of all forms (be they actual drugs, spells or whatever) behave quite predictably, and will invariably have one or more of the following effects on the subject:


 * 1) A person becomes incapable of lying, though still fully conscious and otherwise able.
 * 2) In many cases, the subject seems compelled to not only tell the truth, but to talk, period. Simply shutting up and not speaking, which isn't a lie, never occurs to them—or, if they do try to shut up, they are physically unable to do so.
 * 3) As well, they have a tendency to go into far more detail than is necessary, when short, curt responses that aren't lies could still keep the secret. Compare I'll Never Tell You What I'm Telling You.
 * 4) Occasionally, they will be unable to lie, but quite able to be creative in telling the truth From a Certain Point of View.
 * 5) A victim of fictional Truth Serum almost always gives complete and accurate information, even though in Real Life, people who think they're telling the truth are often wrong.

If the trope-generator is positioned more towards the "Science Fiction" end of the scale, invariably the injectee will start babbling about the Killer Rabbit / Ninja Pirate Zombie Robot / Little Green Men, and be instantly dismissed as crazy or, at best, programmed to spout gibberish under interrogation.

While the body of this entry deals mainly with traditional truth serums, in fiction there are actually many methods of getting the truth out of someone besides drugs. These, due to being Applied Phlebotinum, can be excused for behaving as described herein. Sometimes. Maybe.

For the more historically tried and true method of extracting information by getting the victim completely sloshed on cheap booze, see In Vino Veritas.

May overlap with I'll Never Tell You What I'm Telling You

Anime and Manga
"(In response to "You seem pretty down today. What's wrong?" from a fellow high school girl): "You're right, I'm pretty depressed today. I had a nightmare, ate disgusting curry and even got lectured by my colleagues. Furthermore, my workplace isn't doing very well and the staff has not been up to standard lately. I can't help but worry about meeting this year's minimum visitor count. ... And, for better or for worse, my manager, Kanie-kun is also way too capable. Of course, I'm not exactly jealous of him, I'm just afraid I'm not meeting up to his expectations as his assistant, and—""
 * In Peorth's introductory arc in Ah! My Goddess, Urd gives her sisters a drug that will make them confess to any misdeeds they have ever committed in order to find out about an incident that made Peorth hate Belldandy. When Skuld takes it, she tearfully confesses to a variety of minor misdeeds such as eating all the ice cream. When Belldandy takes it, nothing happens.
 * In Mahou Sensei Negima, in one of the later chapters, as Negi, He got an injection of "truth serum" up his... "back side". It still didn't work.
 * In Amagi Brilliant Park, there's a scene where one of the more perverted characters has got hold of some "Heartsleeve Fruit" and secretly doses Sento Isuzu with it. He intends to ask her lewd questions, such as, it's implied, how often she masturbates. It causes her, for some hours afterward, to babble very detailed answers to even the most casual questions, although once she realizes what's happened, she can cover her mouth and bang her head against something to try and shut up.


 * Making it even worse, she recently realized she's developing feelings for Kanie (the nightmare she mentioned was about him hooking up with other girls) ... so whenever he asks what's bugging her, there's that need to clamp her hands over her mouth again....

Comic Books

 * Perhaps the most famous example is Wonder Woman's magic lasso, which forces others to tell her exactly what she wants to know. Originally it was portrayed without such powers, with the assumption an Amazon with her foot on your neck was a compelling enough tactic.
 * Subverted in an issue of Batman, when Batman uses sodium pentothal on an opponent. The opponent is barely able to answer one question before passing out.
 * Subverted another time when the Joker's henchmen gave him some truth serum in order to get him to tell them where he kept his money. Unfortunately for them, the Joker's state of mind isn't exactly normal at the best of times, let alone under hallucinogenic drugs. Needless to say, the henchmen didn't get anything for their efforts other than mad ramblings.
 * Played with in 52 when Lex Luthor kidnaps a depowered Clark Kent and gives him an experimental truth serum which his scientists explain is a synthetic recreation of Wonder Woman's magic lasso (See above). He then asks Clark, who broke the story about new hero Supernova, why it is that Superman is toying with Luthor by pretending to be someone else. Clark, laughing madly, informs Lex that he does not know who is under the Supernova mask, but he is absolutely certain of one thing, that it is not Superman. Creator commentary in the trade-paperbacks points out that this scene, and perhaps the entire future path of DC comics, could have gone so differently if Luthor had simply known to ask the right question.
 * In a Numbskulls strip, Brainy accidentally switched Ed's truth control from 'true' to 'false'. When the other numbskulls find out, he resets it to 'as truthful as can be.' Ed immediately insults an enormous violent thug.
 * In the Tintin story Flight 714, Laszlo Carreidas is injected with a truth serum to try and pry the number of his Swiss Bank Account from him. He, however, starts confessing to every misdeed he has every done in his life. When Big Bad Rastapopoulos is accidentally injected with the same serum, he and Carreidas get into an argument about who is the most evil.
 * Represented realistically in Diabolik, as lowering compulsions and possible to resist: Diabolik himself was once dosed with it and his interrogators got only a glare, and a man he kidnapped for information for a theft was revealed being an undercover cop who managed to lie without getting caught.
 * 1980's British Starblazer. P 30 M-90 is an extremely potent truth drug. Pentathax is used for the same purpose.

Film

 * Liar Liar has a lawyer compelled to tell the truth (almost nonstop) for 24 hours by his son's birthday wish.
 * In True Lies, Arnold Schwarzenegger's character is injected with a truth serum by terrorists, which also allows his wife, who has also been captured, to question him about his double life as a secret agent. When the interrogator comes back, Arnie tells him all about the plan he had for escaping and killing him, reveals that he picked his handcuffs, then proceeds to do exactly what he said he would.
 * True Lies is a comedy, so this scene is deliberately a bit over the top.
 * Also consider the answer he gives to Helen's first question: "Are we going to die?" Answer: "Yep." (She didn't ask, "Are they going to kill us?")
 * In Valiant, a British homing pigeon is given a truth serum by the German hawks who have captured him. While he tells the truth, he still refuses to actually tell them what they want to know, and instead babbles on and on, annoying them until he accidentally gives them information they wanted to know in the first place.
 * In the film adaptation of Red Dragon, Agent Graham mentions that hospital staff tried Sodium Amytal on Hannibal Lecter to find out where he hid one of his victims. Lecter gave them a recipe for dip.
 * Although considering his... tastes, that might have been his way of telling them without giving them anything useful.
 * Parodied in Johnny English, when the titular inept super-spy gets two gadget rings mixed up. Instead of a strong sedative, he accidentally injects a Mook with sodium pentothal. The Mook becomes not only truthful but extremely helpful, happily obeying Johnny's request for safe directions out of the heavily guarded building before realising in horror what he's just done.
 * In Meet the Fockers, Pam's father Jack, suspicious of Greg, injects him with sodium pentothal. Greg forgets after five seconds that he'd had a syringe jammed into his neck, and proceeds to get on the mic and spill his guts to the whole family reunion about his lust for Pam's mom,, and Pam's pregnancy.
 * Parodied in The Man Who Knew Too Little, where the truth serum works just fine, but because Wally is actually The Fool who's been Mistaken For A Spy, his interrogators don't believe him.
 * Tank Girl. The Rippers try to use nitrous oxide as a Truth Serum to find out if Tank Girl and Jet Girl are spies for Water and Power. It doesn't work at all: the girls only give nonsense responses.
 * The Guns of Navarone. The Germans use scopalomine on Major Franklin to find out the Allied plans. It works, but unfortunately for the Nazis he was (unknown to him) given false information in the hope they would use Truth Serum on him.
 * In Kill Bill volume 2, Bill uses this, his "greatest invention", on The Bride.
 * Bullshot (1983). Having kidnapped Absent-Minded Professor Fenton, the dastardly villain Otto von Bruno tries to find out his secret formula with a device designed to cause "Involuntary Lingual Slippage". After several unfortunate slips of the tongue, the device begins to malfunction, but not before the Professor is forced to admit that the formula is with his daughter who's a pain in the ARRRRRGGGHH!
 * In Return to the Planet of the Apes, Dr. Zira, a chimpanzee biologist who studied humans, is given a dose of sodium pentathol by the locals after a slip of the tongue inadvertently reveals that she used to dissect human specimans. Her ramblings reveal that dissection was only the start of it, and things go sharply downhill from there.
 * To be fair, she is warned that the truth serum will have the same effect as champagne she had earlier, which is basically true: she just got drunk and talkative both times.
 * Jumping Jack Flash. Whoopi Goldberg is injected with a truth serum by Jim Belushi, but she escapes. She then proceeds to say exactly what she's thinking to everyone she meets, including her Jerkass boss.
 * "And that's what happens when you put Ex-Lax in tea!"
 * Robert De Niro's period spy film The Good Shepherd subverts this trope in a disturbing, graphically realistic way. Edward Wilson, the head of the newly-formed CIA's counter-espionage branch, is confronted with a Soviet "defector" who may or may not be who he claims to be. In order to determine the man's real identity,  In case you were wondering,

Literature

 * The Harry Potter books feature a magical truth serum called Veritaserum. It's mentioned quite a lot, but the only time it's actually used was on an unconscious.
 * However, according to J. K. Rowling, all magical truth serums are fallible when used on a victim who is prepared for it, and its effects can be counteracted. Thus it's not useful in wizard courts of law.
 * Parodied in Life, the Universe, and Everything with a character named Prak, who was injected with too strong a dose of truth serum when asked to tell the truth, the whole truth, and nothing but the truth in court. People had to flee his illuminated ramblings or go insane. He forgot most of it (except for the bits about frogs) but was able to tell Arthur Dent where to find God's Final Message to His Creation before dying.
 * Spider Robinson wrote a short story "Satan's Children" about the unexpected positive effects of a drug that made people permanently incapable of lying. It wreaked particular havoc among politicians and prominent religious leaders (although it didn't break *all* of them).
 * Lois McMaster Bujold's Vorkosigan Saga has a truth drug called fast-penta, which when it works properly fulfills this trope perfectly. Inducing honesty is not actually its primary effect, though: what it does is make the subject want to be helpful, allowing the interrogator to suggest that it would be helpful if they would answer a few questions. The distinction is illustrated in Ethan of Athos, in a sequence where fast-penta is used to interrogate a character who is actually entirely ignorant of the subject at issue; instead of explaining that he can't understand the questions, let alone answer them, he attempts to help out by tacitly translating them into questions he can answer and answering those instead, to the confusion of his captors.
 * However, as fast-penta is a drug, not everyone reacts the same way. Most exceptions are fatal allergies. People whose work involves sensitive or classified information can have the allergy artificially induced, unless their lives are deemed more important than the secrets they know. Bujold often uses artificial allergies to keep the characters from learning too much too soon. Another exception to the norm is Miles Vorkosigan. Due to his screwed up body chemistry, fast-penta induces a temporary mania in addition to the typical long-windedness. He uses this to his advantage, forcing himself to be discursive and bouncing off the walls reciting Richard III until his interrogators give up and put him back in his cell.
 * Fast-penta also removes its subject's inhibitions, making them voice whatever is on their mind. So when Ekaterin is under fast-penta, she talks about her sexual curiosity about Miles, to his embarrassment.
 * Bruce Coville's The Skull of Truth (part of the Magic Shop series) has the main character come into possession of a talking skull that forces him to speak only the truth. He finds out, though, that there are different levels of truth (apparently jesters and poets are better at telling the truth more obtusely than others), and ultimately comes face-to-face with Truth him/her/itself, who describes itself as both destroyer and healer. At the end, the protagonist is gifted with the ability to compel people to tell the truth, whether they want to or not.
 * Protagonist of one of Leo Gursky detective comedy series is The Chew Toy Absent-Minded Professor pharmacologist. One of substances he tested was claimed to be "Super Truth Serum" and explicitly said to be pentothal derivative, and he forgets one ampoule in his pocket. Naturally, when Mafia captures him, Mook ordered to search him is a narcoman who barely avoids being offed already, so he stashed it, and soon Hilarity Ensues. Still more believable than usually: aside of talking Mook giggled, drooled and looked like heavily drugged idiot he was, so even after he collapsed boss didn't got what's going on until doc explained it; "euphoria plus logorrhea. ... But it's considered failure. ... See, he said almost nothing and already turned off, and don't forget disordered motor function".
 * In the Harry Turtledove novel ''Worldwar: In The Balance" the aliens try their truth drug on one of the protagonists, but all it does is make him rather giggly. With some difficulty, he manages to keep his cover story straight. The aliens don't know this of course, so they believe his story that he's an innocent civilian and let him go.
 * This may be an illustration of what happens when you try to use truth drugs in real life- they work by lowering inhibitions (which sometimes helps), not by creating some kind of magical compulsive honesty.
 * The fact that it was originally designed for use on aliens with reptilian/dinosaurian physiology (the Race, Rabotev, and Hallesi) instead of mammalian probably didn't help. The Race has had over 50,000 Earth years to work on it so it may work perfectly on themselves and subject species. The alien Fleetlord and Senior Shiplord are later seen discussing that the drug has not been working as well as it should be.
 * In Mercedes Lackey's Heralds of Valdemar series, the Heralds have a two-stage Truth Spell. Stage one functions as a Lie Detector; stage two compels the bespelled person to answer any question truthfully.
 * Unknown to Heralds in most time periods, the spell works by attracting a (previously bound to Heralds) nonsentient air elemental to the subject, and then inducing it to possess him or her. Based on the more detailed description, stage one is actually a slightly more focused polygraph, and there's nothing to prove it lacks the same weaknesses. We tend to see Truth Spell used against people lying to hide powerful and violent feelings, and the spell tends not to show up in time periods where people who can resist possession are present.
 * Phoenix Force uses scopalomine, administered by its team medic Calvin James due to the risk of possible heart failure.
 * No one can tell lies in close proximity to the one of griffins in Tamora Pierce's Tortall books.
 * However, truth spells can be fooled fairly easily, even when you don't have magic.
 * Combined with a Brown Note in the Star Trek: New Frontier novel "The Quiet Place". The Redeemer Overlord, along with a killing word, has a truth-telling word, that compels a person to spill his guts. Almost literally. In fact, it makes the victim tell every truth he's ever known, and then kills him. And then it's subverted in the fact that the victim was trying to get them to stop torturing another victim for information...but they keep going anyway because, even though he did tell the truth, the other victim still could be hiding something.
 * The titular drug of Kallocain by Swedish author Karin Boye made people respond truthfully to all questions. Problem for the Universal State:
 * In The Wheel of Time books, the Aes Sedai have an artifact called the Oath Rod, which binds the will of one who makes an oath while grasping it. Each Aes Sedai before becoming a full sister must swear three oaths using the Oath Rod, one of which is never to speak a lie. However, they tend to become skilled at (and widely distrusted for) making misleading statements while never saying anything technically untrue.
 * In Henry Seslar's short story "Examination Day", when a child reaches the age of 12, they are made to take a Government Intelligence Test. To prevent cheating the child being tested must drink a Truth Drug in a form of a buttermilk-like liquid which tastes faintly like peppermint.
 * The drug compels the subject to answer the IQ tests truthfully, making sure they don't deliberately answer questions wrong, in case a child had found out what happens to those whose.
 * Played fairly straight in the first book of the Blood of Kerensky trilogy set in the BattleTech universe during Phelan's interrogation by the Clans. Of course, the procedure (complete with IV drip for the truth drugs and sensors to monitor the subject's vital signs) was still involved enough to suggest that even (presumably) 31st-century medical science might be able to make this kind of thing effective, but not exactly safe.
 * In Bored of the Rings, a parody of Lord of the Rings, Goodgulf the Wizard used "one of his secret potions " to get the truth about how he obtained the Ring out of Dildo Bugger.
 * In the X Wing Series, it is mentioned that CorSec officers undergo a chemical interrogation as part of their training. When it was done to Corran Horn, he ended up confessing to every childhood misdeed committed in his entire life, which would have been amusing had the interrogator not provided a transcript to his father (A fellow officer).
 * Simon R. Green's Hawk And Fisher series contains a scene in which murder suspects are interrogated under a truth spell. The spell doesn't prevent them from withholding information or answering in a deceptive way, though, so all of them get away with saying "no" when asked if they committed the murders.
 * Subverted in Thomas Pynchon's Gravity's Rainbow. Slothrop is administered sodium amytal twice in the course of the narrative. In both cases he is reduced to surreal babblings and squicky nightmares instead of volunteering information.
 * E. E. "Doc" Smith offers us nitrobarb in the Family D'Alembert series. Nitrobarb totally eliminates the subject's ability to lie or withhold information, but it's difficult to use because the questioning has to be specific and directed. The other big problem is that it carries a fifty percent fatality rate. That's right - half the people who get given it die as a result.
 * Lampshaded in-universe by one of the heroes, who makes it clear that generally speaking they all die, because the information extracted invariably leads to a successful conviction for treason, with the death penalty to follow. When the bad guys use it, the subjects all die because once they've milked you of what you know, you're too dangerous to leave alive.
 * On another occasion the heroes capture the The Dragon and inject them with a conveniently-left-lying-around dose. The information they obtain turns out to be false, but their boss is quick to point out that the dose was too conveniently left lying around, and for all they knew they were injecting them with distilled water. Later, it's discovered that The Dragon is, and it could have been the real thing.
 * Frank Herbert's Dune universe has Verite, a will-destroying narcotic from the planet Ecaz that renders a person incapable of falsehood.
 * Robert Heinlein used this trope a couple of times.
 * Short story "Methuselah's Children". The government uses a truth drug on members of the Howard Families to try to find out the secret of the Families' longevity. It works, but the investigators don't believe what the members tell them and assume they just know the truth.
 * Friday. When Friday is captured by Boss' enemies, they use a truth drug on her to make her tell them about Boss' operations. It apparently doesn't work on her, as she says that she was able to tell them what she wanted to instead simply blurting out the truth. This may be because of her genetically enhanced body.
 * Roger Zelazny included a drug-enhanced interrogation scene in the first of the My Name is Legion stories. The protagonist is able to beat it through a psychological technique he describes as "drug-consciousness" -- rephrasing questions in his mind into versions he can answer truthfully without giving away the information he wants to conceal.

Live Action TV
""Do you swear to tell the truth, the whole truth, and nothing but the truth, so help you God?"\"
 * Long before Liar Liar, The Twilight Zone had an episode in which a used car salesman buys a car its previous owner claims is haunted, and finds himself supernaturally being forced to tell the truth, which is of course especially inconvenient in his line of work. Eventually, a local politician (who for obvious reasons doesn't want the car for himself either) helps him fob the car off as an all-American souvenir to a foreign politician who happens to be in town for a visit:.
 * In V: The Final Battle, the hero Donovan is injected with an alien truth serum and fulfills this trope completely. Of course, this is an alien formula, so...
 * From a Steven Wright comedy routine:

"Yes, I do. You're ugly. See that woman there in the jury box? I'd really like to sleep with her. Do I continue, or are you gonna ask me questions?" "Aeryn: No, don't use that, I won't lie to you. I'll just tell you what you want to know. Battleaxe Nurse: You wouldn't lie to me? (She injects Aeryn at the shoulder.) Aeryn: Yes, of course I'd lie to you, you stupid bitch!"
 * Nothing to do with Truth Serums, really, but too funny to omit.
 * Inverted in Get Smart where Maxwell Smart is given lying pills to foil any possible interrogation. Of course, he takes it at an inappropriate time and suddenly lies about every slightest fact, including his own name.
 * In another episode, he is drugged and ordered to tell his interrogators "everything you know". Naturally, this results in a seemingly endless stream of trivia, including multiplication tables.
 * The Charmed episode "The Truth Is Out There And It Hurts" has one of the sisters casting a 24-hour "Truth Spell" which results in anyone who is asked a direct question having to answer with the truth. Unfortunately it also meant if anyone asked one of the sisters a question, they would have to answer with the truth.
 * The Middleman: The Middleman sets off a truth bomb to get Pip to confess he copied Wendy's paintings. Everyone else in the vicinity starts spontaneously confessing embarrassing truths. Wendy tries to take advantage of the truth bomb to find out the Middleman's name, but he manages to dodge the question by giving her an honest answer that says nothing.
 * Subverted in Star Trek:Deep Space Nine where they inject Quark with 6 doses of sodium pentathol, with no effect. But that's a Ferengi's metabolism for ya.
 * Quark ironically is only too willing to talk, to stop these mad humans from jabbing him with sharp needles.
 * UFO. The 'GL-7 serum' is used on a captured alien, but it either kills him or he somehow commits suicide to prevent himself from talking.
 * Humorously used on Married... with Children after Kelly gets bitten by a swarm of poisonous Samoan beetles during a commercial she's filming for an extermination company. Bud discovers that the Samoan people use the bugs' venom to create a truth serum, and Kelly ends up repeatedly telling the truth at the worst possible times.
 * Played straight on Lost when Sayid is restrained and given an unnamed drug by, and informed that he will have no choice but to answer their questions truthfully. When he does so, the interrogator concludes that he used too high a dose.
 * 24 has occasionally used "hyoscine pentothal" in the past (a fictional substance whose name is taken from the names of two real substances).
 * In the M.I. High episode "Spy Animals", a truth serum causes the teachers to start blurting out what they really think about the students and other members of staff, and causes daisy to tell her friends that she is really a spy. Of course, they think this is a story to cover up the fact that she is going out with Blane. Blane attempts to get daisy to say what she really thinks about him while she is still under the influence, but Lenny gives her the antidote before she can reply.
 * Played fairly realistically in Farscape. When Aeryn is captured by the Scarrans and tortured for information, she is injected with truth serum (from a massive syringe): the drug merely lowers her resistance to questioning while also causing physical pain, disorientation, and eventual unconsciousness. After several rounds of torture and several lies, she finally tells the truth- though by then, she's barely able to speak coherently.
 * Admittedly this didn't stop her from getting sarcastic with the torturers during the first session:


 * An interesting example cropped up on Chuck. In the episode "Chuck Versus The Truth," the villain of the week uses a poison that has the side effect of inducing truth-telling tendencies in its victims. Of course, Chuck, Casey, and Sarah are all ultimately administered the drug. Since this is a comedy, it's mostly played for laughs, as when Casey admits Sarah is better at picking locks than he is. But at the end of the episode, Chuck asks Sarah if she has any real feelings for him. Her answer:
 * Of course, at the very end of the episode, it's revealed Sarah has built up an immunity to truth serums.
 * NCIS ("Truth or Consequences"). A terrorist leader injects DiNozzo with a conconction of his own design consisting of sodium pentathol And Some Other Stuff, causing DiNozzo to give an As You Know recap of the events leading up to his capture.
 * In one episode of The Greatest American Hero, Maxwell is given a truth serum by the General Ripper villain of the story. The resultant babblings about Ralph's supersuit are dismissed as crazy talk.
 * In the Quantum Leap episode "Star Light, Star Bright", Sam leaps into an old man obsessed with UFOs who is dosed with sodium pentothal by government Men in Black. Instead of telling them what his host knows about UFOs, he starts revealing top-secret information about himself and the Quantum Leap project. The Men in Black just assume it's gibberish and that they've given him too high a dosage.
 * In the The Man from U.N.C.L.E. episode "The Foxes and Hounds Affair", Napoleon and Illya are injected with truth serum to make them reveal the location of a device wanted by THRUSH. Napoleon, who is out of the loop this episode and legitimately doesn't know, just starts acting drunk; but Illya is compelled to give up the information after minimal resistance.
 * In an episode of Human Target, the plan is for Ilsa to give the villain of the episode wine dosed with such a chemical so he'll tell them his password. Played with, in that to convince him that it isn't poisoned, she also drinks it herself, after which she tells him the whole plan.

Music

 * The Smyrk's song "The Ballad of Fletcher Reede" is about a man whose girlfriend put sodium pentathol in his Coke, and how he insists that she doesn't want him to tell the truth when she asks him loaded questions.

Mythology

 * In Celtic Mythology Lugh Lamfada's sword, Fragarach, had this as one of its main functions, earning it the name, "The Answerer."

Tabletop Games

 * Dungeons & Dragons
 * The spell Zone of Truth prevented anyone in it from knowingly lying. However, they are not compelled to answer, and can be evasive if they wish.
 * For more fun, the 3rd Edition of Oriental Adventures (based heavily upon Legend of the Five Rings) has an improved version called "Truth is a Scourge" that also forces the victim to answer any question asked. Considering this is set in a land where honor is extremely important, it's rather common for victims to say something that insults themselves or their lord and be forced to commit seppuku to save face - which is pretty much the whole point of the spell.
 * Both 2nd and 3rd Edition had a Potion of Truth that forced anyone who drank it to speak the truth. The 3rd Edition version allowed the drinker to make a saving throw to refuse to answer a question. Also, the Ring of Truth forces its wearer to speak truth and allows to detect lies told by others.
 * White Wolf's Vampire: The Requiem has several methods of forcing somebody to tell the truth, from the gentle to the awesome. On the gentle side, "Majesty" can compel somebody to want to confess their innermost secrets to you. On the awesome side, the "Liar's Plague" causes bugs to swarm out of a subject's mouth when they lie.
 * Changeling: The Lost likewise has a low-level Goblin Contract named Sight of Truth and Lies that lets you automatically tell when somebody is telling a lie. The downside is, if you lie while using it, you'll automatically believe anything but utter bullshit is true when coming from the speaker's mouth.
 * There are a few in GURPS; the Truth potion from Magic as well as Sodium Pentothal and Sodium Amytal in High-Tech.
 * There's also the standard "Compel Truth" spell, and an equivalent psychic ability. Again, despite the name it only prevents victims from lying (if it works...) It does not force them to say anything.
 * The Traveller universe has Truth Drug. The recipient answers questions truthfully for two minutes, then falls unconscious for an hour and takes moderate damage.
 * Paranoia supplement Acute Paranoia, section "Better Living Through Chemistry". The drug Telescopalomine actually works realistically. Clones under its effect answer questions reflexively (not necessarily truthfully) and will be agreeable to anything told them. Internal Security uses it for interrogations.

Theatre

 * Bullshot Crummond. Cranium Stimulus X (the film adaptation turned this into an Applied Phlebotinum device for creating slips of the tongue).

Video Games

 * Subverted during the first Splinter Cell game, at the end of a mission you are required to knock at out a security guard between your extraction vehicle. Two of your allies keep him occupied by talking about interrogation techniques, the one mentioned involves a 'truth serum' that leaves them too drugged out to actually give up anything useful when they talk... but also too drugged out to remember what they actually said. You then convince them they already told you what you wanted to know, and thereby manipulate them into actually telling you.
 * Played straight in KGB but with a slight twist. The serum used by the protagonist at one point is a new prototype and has very severe side effects. Namely, it's lethal, so PC must extract all necessary information quickly.
 * Near the end of Ultima VII, you acquire a magical artifact that can force the Fellowship's members to tell you the truth.

Web Comics

 * Gunnerkrigg Court: Word of God tells us that Antimony's contract of ownership over Reynardine means that he can't intentionally deceive Annie. He can, however, withhold information and refuse to answer questions.
 * In Girl Genius, the Sturmovarus family slips a truth serum into Agatha's soup. She had previously been hiding the fact that she was a Spark or a Heterodyne; the truth serum causes her to lose all inhibition and blurt out her entire backstory in one continuous spiel over three pages, then fall face forward into her dessert before declaring "You're very cute!" to Tarvek as he cleans her up and his father wryly admits that perhaps a bit too much serum had been put in her food.
 * In The Order of the Stick, Zone of Truth works exactly like this.
 * Taking insipiration from Burlew's work, Zone of Truth has the same effect in Murphy's Law.
 * A variation; a tomb-robber in Ballerina Mafia is cursed to have an illusion of the mummy following him around, constantly announcing what he's thinking to all in earshot.
 * In Magick Chicks ninja girl Tandy can do this via acupuncture while giving someone massage.
 * In Dangerously Chloe Gabrielle (the victim of the previous example) slipped some into Naomi's food. And then tried "Getteeng ze truth" from Prudence, but as an angel the latter… began to compulsively spout wildly random lies instead. The human girls thought she just somehow defeated it.

Western Animation
"Alfred: You'll get nothing but gibberish out of me, madam. I come from haunts of cootenfern and knicker sudden Sally. Uh...dee-dum dee-dum dee-dum dee-dum, and bicker down the valley. Red Claw: (shakes her head) And people wonder why no one takes Britain seriously anymore."
 * An episode of Kim Possible had Kim hit by a Truth Ray, with the full effect of the entire trope: not only could she not lie, she was compelled to say anything and everything, in far more detail than was needed. She confessed a crush to members of the sports teams, and told her dad's bosses everything her dad found annoying about them (one tells very bad jokes, one won't stop talking about his home country, and one obviously wears a wig). She ended up covering her mouth to suppress the truth compulsion. Ron, who was hit by the same ray, instead becomes more confident and popular. He does things like admitting to Mr. Barkin that not only did he not read the assigned book, but that it was boring and dumb, earning Barkin's respect by stating an opinion he'd secretly shared, and winning the heart of a beautiful girl by talking about the beauty of her eyes.
 * Subverted in "The Incredible Mr. Brisby" episode of The Venture Brothers, when Dr. Venture is given a truth serum to reveal what his research on cloning has yielded. Apparently, it has an antagonistic reaction with one of the multitude of pills Venture is taking, and makes him think he is some sort of country milk maid and recite lines from Rear Window (which might actually be a realistic reaction).
 * The Batman: The Animated Series episode "The Lion and the Unicorn" has a double subversion: Red Claw injects Alfred with a truth serum to learn the launch codes for a British missile, but rather than submit to her demands, Alfred simply begins hallucinating and babbling incoherent rhymes. After hours of this (and constantly building frustration), Red Claw realizes that the nonsensical babble actually is the launch code. Also the source of one of Alfred's best lines:


 * One rather brilliant episode later on had Scarecrow make up a gas that rendered people subjected to it incapable of fear. While this didn't exactly stop them from lying, it pretty effectively removed their motivations for keeping any socially inconvenient truths to themselves, leading them to do and say all kinds of things they normally wouldn't for fear of the consequences. When Batman himself fell under the influence of the gas, we learned, among other things, that his code of honor against killing is driven more by fear of disapproval than by any actual moral inhibitions.
 * An episode of the Men in Black cartoon had Jay accidentally injected with a truth serum, which resulted in him basically speaking everything that popped into his head.
 * He was perfectly capable of telling a direct lie unless asked a direct question-when first asked by some Muggles what's going on in this whole crisis here, he gives them one of the standard-issue weird-but-believable cover stories. When one of the bystanders finds himself impressed by this, he says, "Wow! Really?" and Jay admits that no, it's actually a cover story to hide the fact that he's a government agent meant to protect them from this threat and cover up the fact that it was ever there.
 * In an episode of Rex the Runt Bob and Rex start drinking what they assume is a truth serum (it was actually orange juice) and, presumably due to their minds making it real started admitted to old lies they'd told in the past, revealing secrets and plenty of assorted lampshading ("Why do you wear that eyepatch anyway? You have two eyes!"). However at the end of the episode Wendy pours the real truth serum down the sink and we cut to a pair of rats in the sewer who start doing the same thing!
 * Also, earlier on, Vince stumbled upon the real serum and drank some of it. It caused him to see two creepy live action guys with cameras, presumably the show's animators, and start babbling "The horror...the horror...". Yes, it's a weird show.
 * This is the main point of the episode "Truth Ache" of The Penguins of Madagascar.

Real Life

 * Happened to the first child who eventually accused Michael Jackson of sexually molesting him. Initially, his father Evan Chandler had been accusing Jackson of sexual abuse of his son, but the son, Jordan, himself wouldn't support the allegations. Eventually Evan, being a dentist, took his son in to pull a tooth and used sodium amytal as the sedative for the procedure. Sodium amytal is known "on the street" as a truth serum and is generally illegal to use in dentistry. Psychiatrists know the drug better for rendering users susceptible to suggestion and being able to induce false memories. It was during this event that Evan claims Jordan first spoke of being abused by Jackson, and it is after this point he began supporting his father's story.
 * The closest things to a real truth serum we have...are alcohol and marijuana. Project MKULTRA found this out the hard way when they discovered that while the more "interesting" mind-bending substances they tried out on unsuspecting subjects were more likely to make such subjects want more substance rather than brainwash them, the FBI had actually gotten actionable intelligence on a bank heist by lacing a captured Mafioso's cigarettes with THC.
 * Hypnosis was once thought to work like this. There is still a persistent myth that it provides perfect and accurate memory recall. Unfortunately, hypnosis is just as unreliable as any other real-life "truth serum," and the human brain is very prone to modifying or making up memories.