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One Dose Fits All

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Seven men take a sip of poisoned wine, and all die within a few seconds of one another.

Belkar: Hey, Ears, what are you doing?
Vaarsuvius: Feeding your [Allosaurus] some rudimentary defensive potions while blocking out all thoughts concerning pharmaceutical dosage specifications.
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Alice has decided to murder Bob and Carol, and serves them each a mug of coffee, into which she has secretly mixed a dosage of cyanide. Both drink their coffee, and five minutes later both Bob and Carol begin to dramatically cough and clutch at their chests, each dying within about ten seconds of one another.

But hang on - Carol gulped her coffee back in a few mouthfuls, whereas Bob sipped his and barely drank half of it. Additionally, Bob is six feet tall and weighs nearly twice as much as the petite Carol. How can the same poison possibly have killed them both at the same time, given the differences in body mass and how much poison each of them consumed?

This trope refers to those Fridge Logic-y moments in which a poison (or sedative, tranquillizer, medicine etc.) is administered to several different people and takes effect on all of them after roughly the same period of time and with the same effects, despite differences in body mass, how much of the substance was administered and constitution. Sometimes the people affected are even of different species, such as a poison simultaneously administered to both an adult male and a dog, who nonetheless react identically to any poison administered. Supposing that, in our example above, Bob is a human whereas Carol is a three-headed Martian whose species evolved under entirely different circumstances to our own; how could we possibly expect Carol to react in the same way as Bob to being poisoned (sedated, etc.)?

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One way to Hand Wave this in-universe is for the poisoner to explain that they based the dosage on the heaviest person present, and administered the same amount to everyone. However, if that was the case, the poison should presumably take effect on the lighter individuals significantly earlier than the heavier ones, rather than everyone being affected within a few seconds of each other; and you still run into the problem of the dosages being inconsistent (if, for example, Bob drank more or less coffee than Carol). Additionally, this explanation doesn't work in the case of sedatives or tranquillizers: if you base your dosage on the mass of the heaviest person present and administer the same dosage to a lighter person, it could potentially not just render the lighter person unconscious but also cause brain damage or even death (this is why anaesthesiology is such a complex discipline).

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This trope is related to, but distinct from, Instant Sedation. In Instant Sedation, a drug is administered to a person or group of people and the drug takes effect after a very brief space of time (say, a few seconds). In this trope, it does not matter how long it takes the drug to take effect (from a few seconds to several days), as long as it takes effect on all of the victims after roughly the same period of time (despite differences in dosage, body mass, and constitution). The two tropes can often overlap, however.

In Video Games, if a poison or sedation mechanic is featured it's very likely to be an example of this trope, assuming the enemies the poison or sedative can be used on are of diverse sizes and constitutions. This could probably be considered an example of an acceptable break from reality or an Anti-Frustration Feature, as enemies responding differently to drugs depending on their size wouldn't exactly be a meaningful test of the player's relevant skills, and would be more likely to annoy players more than anything else. In addition, if hit points scale with size and constitution a poison that does hit point damage does take more to kill larger creatures.

A sub-trope of Artistic License – Medicine, Artistic License – Biology, and Artistic License – Pharmacology. See also Instant Sedation, Tranquillizer Dart, Knock Out Gas, Deadly Gas, Slipping a Mickey, and Tampering with Food and Drink. Frequently applies, even more illogically, to the Healing Herb. If the same drug affects people the same way despite differences in species (including, for example, humans and aliens in Speculative Fiction works), this trope overlaps with No Biochemical Barriers. For a more violent and equally unrealistic means of rendering someone unconscious, see Tap on the Head.

Note: The key element of this trope is that it shows the same substance affecting more than one entity (human, animal, alien etc.) in the same way, even if it logically shouldn't (because of differences in dosage, body mass, constitution, species, etc.). If you have an example of a poison or sedative etc. affecting just one individual, it's not this trope.


Examples:

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    Fan Works 
  • Chrysalis Visits The Hague averts this: One time, everybody thinks that Chrysalis is out cold due to the ridiculously high dose of horse tranquiliser she's been given (which would have outright killed any other animal in her weight class). Then she jumps up...
  • Averted in First Knight. Xander mentions having a single dose of the antidote to the poison used in the lobster at a dinner set in the 1930s because he didn't expect to take anyone else back with him. However, he explains that the dose is tailored for his weight and metabolism; he could use a smaller amount if Willow or Dawn got poisoned, but has no idea how to account for a Slayer's constitution and metabolism. As a result, he can't do anything to save the poisoned alternate Xander and Faith they meet.
  • Zigzagged in Scrap Value when Xander doesn't give any painkillers to injured Skrulls because he has no idea what affect they'd have on them but is assured that alcohol and marijuana have the same effect as on humans so they drink and smoke to dull their pain.
  • Averted in The Dragon King's Temple:
    • Janet explicitly refuses to give Zuko and Toph any medicines (even aspirin) because they are Asyuntians, not humans, and she cannot reliably predict what effects any given medicine might have on them.
    • It turns out that the neurotoxin the System Lords use to kill their human hosts is actually intended to allow a Gou'ald blended with an Unas to separate safely without harm to either party.

    Films — Live-Action 
  • In Mindhunters, the killer sneaks a sedative into the pot of coffee the team is drinking from. It takes effect a few minutes later and every team member is out cold within about thirty seconds of each other, and similarly wake up within a minute of each other several hours later. Never mind the disparities in how much coffee each team member drank or that the team includes six team members ranging from a burly Scary Black Man to two petite women (however, one of the team members gets murdered while asleep and another is the killer himself who merely feigned unconsciousness, mitigating this slightly). And this is possibly the least impractical element of the killer's insanely complicated Gambit Roulette.
  • When the Pink Berets from Illumination Entertainment's Hop are discovered near the iconic Hollywood sign by a patrolman, they shoot one blowgun dart to his neck, which drops him unconscious almost instantly. Later, when the Pink Berets encounter Fred O'Hare in the mansion's kitchen, the bunnies think that Fred has killed their charge, E.B. Fred gets a volley of six darts to the face, which ought to be fatal, or nearly so. Nope, it only keeps him in la-la land for a few hours. Somewhere, a pharmacist is crying...
  • Outbreak shows everyone getting the cure to Motaba in IV bags, although it's never specified whether the cure was titrated individually for each patient or if every IV bag contained the same dosage.
  • In the opening scene of The Rock, the mercenaries use tranquilizer darts on the soldiers guarding the chemical weapons depot. All of them fall unconscious practically immediately, despite their different sizes.
  • In The Adventure of Sherlock Holmes' Smarter Brother, Sacker puts pills in the wine during the opera scene. When the various actors drink the wine, they instantly collapse.
  • The climactic trick in The Incredible Burt Wonderstone can only work if this applies on a massive scale with near-perfect simultaneity. Even worse, it has to apply to both onset and recovery because anyone who resists the gas even slightly to either stay awake a little longer than average or wake up a little sooner than average will notice that people around them are sleeping, which would be a pretty big tip-off. Of course, it's a comedy, so Rule of Funny is in full effect and we're not supposed to worry about that.
  • In Dr. No, Bond and Honey both pass out from drugged coffee provided by the villain. Honey does feel the effects first, but only by a few seconds despite being much smaller than Bond. Strangely, there were already captured and no real explanation for why they were drugged is given.
  • In X2: X-Men United, the soldiers attacking the Xavier mansion use the same tranquilizer darts for grown adults as they do for small children. The only ones who aren't knocked out instantly are Wolverine due to his healing factor and Colossus due to his metal body.
  • Denial: Deborah points out that Fred Leuchter, the supposed "execution expert" who claimed to debunk Auschwitz as being an extermination camp because more gas was used to delouse lice than kill the prisoners, assumed this when comparing them. In reality, it takes twenty times more gas to kill lice than humans.
  • Averted in The Wizard of Oz. The Wicked Witch's poppy field causes Toto to fall asleep first, then Dorothy, then the Lion — the biological characters are affected from smallest to largest, while the non-biological Scarecrow and Tin Man remain unaffected.

    Literature 
  • It's implied that the Invisibility Potion from Murderess works this way: Lu, Hallwad, and Aucasis have presumably the same body mass, give or take, but Hallwad, and especially Aucasis, have both been injured pretty badly by the Dark Ones, and their loss of blood does not seem to be accounted for when dividing the potion Lu still has.
  • Discussed in Jurassic Park. Muldoon points out that the same dose of tranquilizer will knock an elephant unconscious, make a hippo sleepy, and make a rhinoceros angry. So he has to make an educated guess about proper tranquilizer dose for an adult T. rex. As it turns out, much more than he expected. The T. rex takes an hour to even feel the tranq shot.
  • In the third Redwall book Mattimeo, Slagar the Cruel successfully drugs an entire abbey into unconsciousness with a toast, with apparently adult badgers, adult mice, and their children all taking the dose amount. The only two exceptions stayed awake because they were distracted during the toast so Slagar's goons just murder them.
  • Averted in Dune. When Jessica and Paul are sedated and abducted, Jessica manages to figure out who the poisoner is by narrowing it down to the only person who would have had access to the medical data necessary (weight and metabolic rate are mentioned, others implied) to make the individual doses so precise.
  • Downplayed in the Artemis Fowl series. Sedatives usually knock out people at about the same rate and they wake up at about the same time, but there's always a mention of the sedative being measured for each individual's body mass. In The Time Paradox, Artemis and Holly get knocked out with the same dose, but Holly wakes up first in spite of being lighter. Once Artemis wakes up, he points this out, and they both attribute it to Holly's magic.
  • Danny, the Champion of the World: Danny believes this, and it makes him slightly worried; his big plan hinges on being able to drug two hundred pheasants with fifty sleeping pills. His father points out that a pheasant is only a fraction of the size of a man, so if a pill can put a man to sleep, a quarter of a sleeping pill will be more than enough to knock out a pheasant.
  • The Golden Gate, by Alistair MacLean. The authorities slip a sedative into some of the food sent in to the criminals and their hostages. Unfortunately a hostage scoffs down his food immediately and dies of an overdose.
  • The Andromeda Strain. In order to stop a nuclear Self-Destruct Mechanism from going off, Dr Hall has to take a shortcut by climbing up a shaft equipped with automated guns firing curare-tipped darts to stop any potentially infected escaped lab animals. Luckily, the dose was calculated for primates less than 20 kg, and not for much larger humans. Of course, that depends on how many times you get shot...

    Live-Action TV 
  • Averted in The A-Team episode "Deadly Manuevers". B.A. and Hannibal both drink the spiked milk. However, B.A. drinks five glasses. He feels the effects very soon and doubles over on a number of occasions, eventually being barely able to move. Hannibal, presumably having drunk less, feels the effects but is able to stay on his feet long enough to get away from the bad guys, find a safe area, and call Tawnia to tell her to fetch a doctor.
  • Breaking Bad. In "Salud", Gus proffers Don Eladio of the Mexican cartel a bottle of poisoned tequila, which he serves to Gus and his men, and also takes a shot himself (Gus has already taken an antidote to minimize the effects, and shortly afterwards induces vomiting to get rid of what he could). Sometime later, the Don and all of his men drop dead within a few seconds of each other, despite the differences in size between them (the man standing guard outside the bathroom when Gus is making himself sick is easily twice the size of the Don himself, for example).
  • Game of Thrones:
    • The series features a drug called "Essence of Nightshade". It's not seen being used, but Pycelle (the setting's equivalent of an apothecary) claims one drop is a powerful sleeping agent while ten is fatal, which ignores the body mass of the victim.
    • Played ridiculously straight now in season 7, Dragonstone. When Arya, disguised as Walder Frey, poisons the wine and then instructs several dozen members of House Frey to have a toast, all of them are largely fine for the time it takes her to finish her speech, at which point they all die within seconds of each other.
  • Parodied in the first Blackadder series (which provides the page image), where one of the seven plotters doesn't die of poisoned wine, has another, then dies.
  • On Zoo, the same tranquilizer darts which take down a brown bear via Instant Sedation are also used on big cats less than half its size, and a German shepherd which couldn't have weighed even 1/10 of what the bear did.
  • In an episode of The Flash (2014), The Trickster laces the champagne at a Gala with a poison that takes one hour to take effect. For all the guests. Like clockwork too — one guest, who arrived an hour before the rest (and therefore an hour before everyone is told about the poison) starts to keel over precisely sixty minutes after he started drinking.
  • Done hilariously in one episode of Due South, when a train car full of Mounties is gassed while they are singing, everyone present falls asleep within a minute. When the gas wears off, not only do they all regain consciousness simultaneously, they all go from out cold to continuing singing, right at the point where the last person to fall asleep left off instantaneously.

    Music 
  • In Lady Gaga and Beyoncé's video for "Telephone", they decide to not only poison Beyonce's jerkass boyfriend but also everybody in the restaurant. Beyonce's boyfriend dies first but then everyone else croaks at the same time.

    Tabletop Games 
  • Zig-zagged in Shadowrun: drugs, toxins, and other chemicals affect every character equally with the same nebulous quantity of a single dose, whether it be an ordinary human, an ork built like a pro linebacker, or a two-and-a-half meter, three-hundred kilogram troll. The only concession made for different body sizes is that the subject's Body attribute reduces the duration of the effect to a minimum specified in the chemical's description; the troll will fall asleep when laës'd, even if it's the same size dose as the human got, but he'll wake up sooner and remember more.
  • Zig-zagged in Dungeons & Dragons 3.5 and other D20 tabletop games where poisons come in fixed doses and require Fortitude saves to resist and successfully eliminate, and Fortitude varies depending on Constitution, class levels and racial hit dice (sometimes bigger creatures have higher Constitution, but not always). Poisons are for the most part "save or suck"; you either successfully resist and are unaffected or you suffer the full effect, making them a bit of a gamble and somewhat inconsistent.
  • The Pathfinder system tries to make poisons more consistent by allowing additional Fortitude saves after the initial injection/ingestion to cure it, and enabling the stacking of several doses to increase their save DCs.

    Video Games 
  • Played straight throughout the Hitman series. Any poison or sedative administered to any NPC will be equally effective on any of them. Sedating an NPC with a given amount of chloroform will knock them out for a fixed period of time, regardless of whether they are a petite woman or a burly Russian gangster. There is also at least one instance in which a possible means to assassinate two targets is to serve them the same poisoned drink near-simultaneously, following which they both drop dead within seconds of each other despite their different sizes.
  • Metal Gear:
    • Zig-zagged in Metal Gear Solid 2: Sons of Liberty, due to Gameplay and Story Segregation. This game is the first in the series to feature tranquillizer-firing weapons, with which enemies can be dispatched non-lethally. Tranquillizer darts will be equally effective on any regular enemy regardless of size (only location of the shot makes any effect - a guard will feel the prick of the dart and try to find where it came from for a few seconds before falling unconscious if he's shot in the hand, but a dart to the head is instant sedation), provided they are not wearing full body armour, making this a straight example. In boss fights, however, it's played with. Bosses can also be defeated non-lethally, but rather than knocking them out with a single dart to the head, they instead have a "stamina" bar (much like their regular health meter) which depletes the more they get hit by tranquillizer darts. However, this stamina bar is based not on the enemy's size, physical fitness or constitution, but rather simply scales up linearly as part of the game's difficulty curve. So it's averted, but in the interests of gameplay rather than realism (could be considered an Acceptable Break from Reality, as the boss fights would be very anticlimactic if the bosses reacted to tranquillizer darts the same way the regular enemies do).
    • The above description also goes for the third game in the series.
    • It likewise applies to Metal Gear Solid: The Twin Snakes, a Video Game Remake of the first game which essentially remade the first game but with all of the mechanics featured in Metal Gear Solid 2.
    • Metal Gear Solid 4 played it almost exactly the same as well, which gets particularly silly considering the game has a greater focus on gunplay and on how enemies react to getting shot. You can hit a man in the face with a tranq dart fired from an old Soviet bolt-action rifle and send him backflipping through the air, and he'll be out cold before he has any time to wonder what the hell just happened.
  • Second Sight features a tranquillizer gun. Any enemy hit by a single dart will be out cold indefinitely, regardless of size or constitution. A body shot will take some time to take effect, whereas hitting them in the head or neck will knock them out instantly.
  • The tranquillizer rifle in the original Manhunt will knock out all enemies practically instantly, regardless of size.
  • The tranquilizer rifle in Far Cry 2 takes it to absurd lengths, as whatever kind of tranquilizer and dosage it's using is enough to instantly kill any enemy you shoot with it, regardless of size or shot location.
  • Dwarf Fortress has the option to give an individual venom this feature. Taking existing game creatures as an example: Giant Cave Spider venom (which causes paralysis) averts this, and behaves realistically in that its effects depend on mass. Therefore, its bite will paralyze a dwarf to the point they'll asphyxiate and die, but a dragon will only feel mildly numb, and possibly be inconvenienced after multiple bites. On the other hand, Giant Desert Scorpion (a neurotoxin, or the closest the game can manage) venom plays it straight: Its sting will, eventually, kill a dwarf, a dog or a dragon in the same amount of time, by way of making their entire nervous system (brain including) necrotize and rot away.
  • Tranquilliser darts in Alpha Protocol affect all normal enemies the same way, regardless of size. Boss battles are another matter.

    Web Comics 

    Western Animation 
  • The Simpsons: As a bear wanders through Springfield, Chief Wiggum tries to shoot it with a tranquilizer dart. The first shot hits Barney instead, while the second shot connects. Both Barney and the bear react the same (despite the differences in time of administration, body mass, constitution and species), and there is no indication that the tranq shot into Barney gave him any long-term ill effects. Then again, this is Barney we're talking about; mere tranquillisers are nothing compared to what he puts his liver through on a regular basis. In fact, he only succumbs after he pulls out the dart, breaks it in half, and drinks the contents.
  • In the first trailer for Zootopia Judy shoots Nick (a fox) with an elephant tranquilizer and it only knocks him out instantly (instead of realistically killing him) , then a wildebeest eats the dart and staggers for a second before passing out. The tranq gun was left out of the final film but blueberry-sized capsules of Night Howler serum is show to equally affect animals ranging in size from an otter to a polar bear. And since it's a contact toxin that's absorbed though the skin, the dosage would be even more random due to the targets having fur coats that have varying degrees of waterproofing.
  • Averted in American Dad!. Stan drugs Steve and his friends with spiked cheeseburgers so he can put them in the CIA holograph deck and force them to have outdoor adventures like he had as a kid. Steve, Toshi and Snot immediately nod off after a few bites... but not Barry.
    Barry: Mine's not working!
    Stan: Have three more!
  • Played with in Archer: Archer's friend Lucas drugs Archer's wine, for which he may well have correctly calculated the dosage required as Archer passes out reasonably quickly, and Lucas knew ahead of time that he might need to drug Archer. However, he drastically underestimates Sterling's liver's ability to metabolise toxins, meaning Archer wakes up much sooner than anticipated.

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