Magic Antidote

In Fiction land, antidotes and vaccines work almost instantly. The fever goes down, color returns, heartbeat and "life signs" stabilize, the characters open their eyes, etc. Furthermore, to build dramatic tension, the poisoned character is usually given a very precise... um... deadline to take the antidote, and only manages to get the antidote right before death.

This isn't how it works in Real Life, as the damage the poison does still needs to be healed. It has ontological inertia... The time it take for poisons to kill tends to be quite variable, and usually, the time at which the body has sustained so much damage that death is inevitable, even with an antidote, comes much earlier than death itself.

Also, shows are a tad liberal with the word "vaccine". A vaccine is a means of teaching your immune system how to attack a particular disease-causing agent. They contain pieces of the bacteria or viruses or an inactivated version of it, and so are unable to cause the disease; but since they "look" the same to the immune system, it learns what they are like, and prepares the tools to fight them. If the real thing ever comes along, the response will be fast and strong and squelch the disease before it ever gets started. Vaccines only work against something caused by a pathogen, like a virus, and won't work against diseases which are due to genetic defects, bad diet, and so on. Most of the time, it's a preventative measure, but there are a few vaccines that can be taken after infection (since the diseases in question stay dormant long enough for the body to develop a defense).

Long story short, a vaccine wouldn't be very effective once a character's symptoms develop, let alone in the 11th hour right before said character is about to die from the disease as this trope describes.

Antidotes are even worse. Fictional antidotes are benevolent drugs that exactly reverse the effects of a poison. They may even visibly reverse their ravages, such as Tainted Veins. In Real Life there are only two drugs that reverse each other's effects -- and they are both deadly poisons. Antidotes are various drugs that help counteract some effects of a poison.

Sometimes, writers will try to excuse this by suggesting that the recently-cured hero's drive and inner strength is enough to restore them temporarily, but, we are assured, they're going to have to spend some time in the hospital right after the end credits roll. The very real prospect of liver or other internal organ damage is rarely even hinted at.

If worst comes to worst, Hand Wave it with The Power of Love.

Compare to Instant Sedation. See also CPR: Clean, Pretty, Reliable.

Almost always the finale of Find the Cure episodes.

Anime & Manga

 * Averted in Dragonball Z, where Goku takes the antidote to his disease almost immediately after exhibiting symptoms and still spends several episodes in bed.
 * Ranma One Half
 * The Phoenix Pill: meant to counteract the effects of the Full-Body Cat's Tongue (an acupuncture technique that makes the victim unable to tolerate even the slightest amount of heat,) this pill can make the user impervious to heat, or at least restore his tolerance to ordinary levels. Given that Ranma nonchalantly dropped into a lake of boiling water while swallowing it, it's assumed it works instantaneously.
 * Ditto the mysterious, powdered medicine that the perpetually ill Densuke took. Despite his unspecified, yet presumably lethal lifelong illness, all it took was one dose of the powder for him to wake up the next morning in full health.
 * The antidote for the Super Soba powerup also works instantly: after spending at least a whole day enjoying super-strength (and, in the last few minutes, a cute set of cat-like whiskers), Akane swallowed the tiny fruit and instantly returned to normal, facial hair included.
 * In Naruto, Sakura creates an antidote to Sasori's poison that can be used both to cure someone after they've been poisoned and, if taken in advance, instantly neutralize as soon as it enters the body. However, it doesn't repair damage already done by the poison.
 * Played ludicrously straight in the Sengoku Basara anime: Kojuro is facing the resident Magnificent Bastard Matsunaga Hisahide and gets poisoned twice (first with a low level poison, then with a poison that makes the former deadly), and is seriously weakened. Then Sasuke passes by and gives him the antidote in form of a gas. Two deep breaths later Kojuro (who was enfeebled just a while ago) proceeds to send Matsunaga flying in a single Sword Beam.
 * Scrapped Princess has Pacifica being poisoned, and her companions having to seek a cure. Of course they first have to seek a doctor to tell them about the cure, most of the deadline is used up, yet of course this is only episode 5 so.

Fan Works

 * In The Draco Trilogy, Draco is literally about three seconds from death when his saviour runs into the room, tips some antidote down his throat, and promptly collapses into a coma herself. When she wakes up a few hours later, he's fine.

Films -- Live-Action

 * In Outbreak, one of the CDC doctors contracts the disease (a hemorrhagic fever with a near-100% fatality rate), and is hanging on by a thread when she's given the antiserum. Barely a day later, the splotches on her skin have disappeared, and she's looking tired but otherwise perfectly fine. FYI, hemorrhagic fever causes massive internal bleeding and organ damage. Much of this damage should be permanent even if the disease was arrested, and certainly would not be healed in a single day.
 * Star Trek First Contact uses the scientifically laughable idea of an inoculation against radiation.
 * Iron Man 2. Yet when he, the visible symptoms recede immediately.
 * He also received an injection developed by SHIELD specifically for his case, which temporarily reverses the toxic effects.
 * In Indiana Jones and The Temple of Doom, Indy is double-crossed and poisoned by Lao Che, so the former would return a diamond to the latter in exchange for the antidote. Chaos ensues, and all the while Indiana becomes progressively dizzier, hotter, and has difficulty breathing. When he swallows the antidote, all these symptoms disappear almost immediately.
 * Batman Begins. The antidote to the fear poison took mere seconds to not only undo its effects, but also conferred resistance for days. This might be a bit justified, as some drugs which counteract psychoactive substances have a very quick onset.

Gamebooks
How rare is it? There are only two doses of Oede in the entire series. And you can only get the one in Book 5 if your arm gets infected.
 * In the Lone Wolf series, Oede Herb is the rarest and most expensive medicinal plant on the whole Magnamund. But it can cure many diseases and poisons, and its effects are nearly instantaneous. In Book 5, Shadow on the Sand, the hero recovers the usage of an arm paralyzed by infectious bacteria in mere seconds.

Literature
"Bleeding and weak I reached my women, who, accustomed to such happenings, dressed my wounds, applying the wonderful healing and remedial agents which make only the most instantaneous of death blows fatal. Give a Martian woman a chance and death must take a back seat. They soon had me patched up so that, except for weakness from loss of blood and a little soreness around the wound, I suffered no great distress from this thrust which, under earthly treatment, undoubtedly would have put me flat on my back for days."
 * The Star Wars Expanded Universe expands on the properties of bacta, which while not an antidote is basically a heal-all, cure-all -- it's said that if there's any life in someone, bacta will help. Naturally, this makes it very valuable. There are still things it can't fix, usually for plot-related reasons. It can't fix missing limbs or organs, for example, so prosthetics crop up a lot. Ton Phanan is allergic to bacta, and so he keeps needing prosthetic replacements for more and more of his body.
 * Prior to bacta, everyone used kolto, a substance collected only on one planet - the water world of Manaan. That is why Manaan was able to remain neutral during the Jedi Civil War - both sides needed kolto to heal its wounded troops, although both sides also knew that their neutrality was shaky at best. Realizing this, the Selkath (Manaan natives) officials were secretly working with the Republic on increasing their supply. Eventually, bacta replaced kolto entirely.
 * The Martian curative arts in Edgar Rice Burroughs's John Carter of Mars.


 * Averted in the Malloreon -- it takes Zakath several days to recover from thalot poisoning.
 * In the Time Scout, lots of Snake Oil Salesmen sell these on Shangri La. Skeeter starts such a scam but gets interrupted. Ianira may just make the real thing. Skeeter's scheme was based on a Sacred Pool believed to have such properties near Marcus's childhood home.
 * A spoonfull of an orally-taken cure for the Sickenesse in Septimus Heap takes only a minute to awake a person suffering from it.

Live-Action TV

 * Star Trek: Federation medicine is generally pretty swift. Just to name one example, in "The Deadly Years" we see the effects of a disease that causes accelerated aging reverse before our eyes in response to a shot of adrenaline.
 * Compare to Stargate SG-1's take on the same concept, where O'Neill's rapid aging takes weeks of off-screen time to reverse.
 * MacGyver: Though we're told he still needs to see a doctor, Mac seems fully restored within seconds of taking the cure for tetrodotoxin poisoning.
 * Possibly subverted (but then again, maybe not) in an episode of The Burning Zone: an infected airplane pilot is given the cure to an ebola-like virus, but dies anyway because the damage to his organs was already too severe. On the other hand, upon receiving the cure, he instantly regained enough strength and clarity to land the airplane, destroyed organs and all.
 * In the 2000s Battlestar Galactica, receiving an infusion of blood from a half-Cylon fetus spontaneously caused President Roslyn's cancer to go in remission, at a point where she was hours away from death.
 * Averted hard during the Kobol arc, one of Tyrol's men is wounded and his lungs are slowly filling with fluid. They used the last of the medication to treat this in one of their medkits, and they left the other medkit by the Raptor crash site in their haste to evacuate the area. Tyrol, Cally and a Red Shirt have to go back for the medkit before the wounded man dies.
 * House is regularly guilty of this one (though they've been known to subvert it as well). Patients frequently make full and speedy recoveries once the cause is found, despite suffering what should have been irreparable damage to their bodies in the meantime.
 * The most bizarre example is probably season two's "Euphoria". How on earth can
 * In Buffy the Vampire Slayer, Angel is approaching his final moments due to a nasty poison, yet he was still able to pick up an unconscious Buffy and carry her to a hospital immediately after getting the antidote. Of course, he's already dead, so it's not clear what kind of damage the poison was doing in the first place. It's explicitly a magical poison, and the antidote, a Slayer's blood, doesn't cure him so much as magically eradicate it.
 * Handwaved in Andromeda by saying it was his unique physiology that made the cure work so fast. Reasonable enough because, the same physiology also made the disease work faster than usual.
 * Doctor Who, "The Christmas Invasion". One minute he's sick enough to only have one heartbeat, and the next he's sword fighting the leader of an alien invasion force. The fact that the cure is apparently tea is just the icing on the weirdness cake.
 * Are you saying tea isn't supposed to be a Magic Antidote?! At any rate, maybe he'd just finally got enough rest. As for the antibiotic in "New Earth"... apparently the slightest exposure to antibiotic turns staggering sacks of disease into peaky but fairly healthy people in an instant. That's Who soft science for you.
 * Tea also provided the fix for Craig's encounter with the "rot" in The Lodger. From what sense can be made of the Doctor's mutterings, the (very strong) tea enhanced some natural process that was fighting the infection, and if Craig had touched the mold more than the tiniest amount, he'd be done for.
 * It's a British show. Of course tea is the Magic Antidote. There's a large chunk of the British population who would argue that this is true in Real Life.
 * Doctor Who has been using this trope all the way back since its first season with "The Sensorites".

Tabletop Games

 * Subverted in Dungeons and Dragons. Curing poison or a disease will stop things getting worse, but damaged attributes need to be restored separately. Natural healing is fairly slow and can be accelerated with expert care and bed rest -- and some particularly nasty kinds of damage (generally from supernatural sources) can never be naturally healed, requiring magical intervention to repair.

Video Games
Also, expect all ailments like poison, disease, being afflicted by time in some way, confusion and sleep to be cured instantly if you can find that one right damn thing at the bottom of your items list.
 * Also subverted in Suikoden V. The Hero's Rune has the power to keep Lyon from dying when she gets stabbed and poisoned, but she still has to spend a long time in bed recovering from the damage.
 * Used in Treasure of the Rudra
 * In games in which there is healing magic, it's very curious that it manages to medically cure stab-wounds (both superficial and serious), magical burns and electrocution, the bodily damage caused by poison, beatings from blunt weapons, etc.
 * Of course, a Magic Antidote literally being magical helps with handwaving broadness of applicability, speed of effect and reversal of already done damage.
 * Final Fantasy
 * In Final Fantasy IX, a "soft" (whatever that is) can instantly cure a character that has been turned to stone, except, of course, if you've been turned to stone by a forest, in which case you need to spend a quarter of a disc searching for a 'supersoft'.
 * There's also a "vaccine" that can cure a viral infection after the fact.
 * In Final Fantasy IV, when Palom and Porom, normal curative magic doesn't solve it, supposedly because
 * In Kingdom of Loathing, ailments can last an inconveniently long time, leading to an adventurer's "Beaten Up". But the anti-anti-antidote un-un-unpoisons you in a jiffy!
 * Subverted in Dawn of War II, the mighty Space Marine Captain Davian Thule is poisoned by the Tyrannids and you must develop an antidote. The antidote stops further damage and keeps Thule from dying, but the organ damage done already is so extensive that he must be put in a Dreadnought sarcophagus to survive.

Web Comics

 * Subverted in Order of the Stick. Varsuvius gets hit by a poisoned arrow which penalizes his/her Strength. Elan Neutralizes the Poison. That stops the Strength drain, but V is still weakened by the toxin.

Western Animation

 * Zoom in the Hot Wheels Battle Force 5 episode "Man Down" fits this trope to a "T".
 * In Wakfu episode 7, Amalia is bitten by a devil rose, and the only cure for the poison is a very rare glowing sap from a magical tree. Note that, unlike with many other examples, the actual monetary value of the antidote outside of the current plot is implied: Ruel takes the time to fill several vials of sap that he intends to sell later. This ends up saving Amalia's life, since Yugo quickly loses the only vial he'd intended for his friend. Even though she was close to death, the effect on Amalia is instantenous, as usual.
 * Averted in Korgoth of Barbaria, where Korgoth must take the antidote for several seasons for it to work.
 * Possibly Subverted in a Find the Cure episode of Generator Rex. The individuals affected by the poison are shown on IV drips after the cure is found, implied to have been there overnight, and it's never said quite how long they had to find it.

Real Life

 * Naloxone, a/k/a Narcan is a more or less instant antidote for opioid overdose; given intravenously, it takes effect in less than a minute and completely reverses the effects of heroin, morphine, codeine, fentanyl, and all the derivatives thereof. However, it does nothing against anything else the patient might have dosed themselves with (benzodiazepines, such as Valium, and barbiturates, such as Seconal, are commonly cross-abused with opioids, and Narcan will not treat an overdose of these), and it tends to wear off before the drugs do (necessitating a re-dose or even an intravenous drip of the stuff while you wait for the drugs to clear out). Other possible drawbacks include nausea, diarrhea, hypotension (low blood pressure), and the patient instantly going from unconscious and apneic to wide awake, stone cold sober, and very much aware that the emergency services staff just ruined their very expensive hit.
 * For a while Penicillin looked like it might be this. During WWII, a shot of penicillin would clear up an normally fatal infection and return the soldier back to fighting shape in a about a day. Of course, the rise of antibiotic resistance made sure it did not stay that way for long.
 * Insulin functions like this against Type I (insulin dependent) diabetes. The three scientists who discovered it used a crude extract of it on a ward of fifty patients who had become comatose due to hyperglycemia. By the time they were injecting the last patients, the first patients were already coming out of their comas.
 * Adaptogens are more or less a low-grade version of this. Not an instant-acting panacea without any contradictions, but they act via very low-level and thus universal mechanisms that either counteract or compensate for lots of unrelated highly toxic substances. Enough to make a difference in some cases as big as 2x improvement in LD50 or five times quicker recovery.
 * The Placebo Effect plays a part in Real Life examples mild enough to be believable. Where no irreparable damage has taken place, administration of a curative (or believed curative) relieves the distress of the symptoms enough to function as if they were already gone.
 * Good old Aspirin. It's one of mankind's oldest and simplest medicines, but the uses to which it can be put are quite startling, with new ones being found on an almost monthly basis. Notable examples include prevention against lots of clot-related diseases, including heart attack, deep venous thrombosis, and stroke.
 * This month's new use: Bowel cancer treatment
 * Magnesium sulfate is one of the only effective treatments for a specific arrhythmia, torsades de pointes (a very nasty form of ventricular fibrillation that isn't responsive to the usual combo of CPR: Clean, Pretty, Reliable and Magical Defibrillator treatment). It's also quite handy for rapidly breaking severe asthma attacks, as well as stopping premature labor and seizures in eclampsia.
 * TPA, a powerful decoagulant, can (in fortunate cases) reverse many of the effects of a stroke remarkably quickly, by breaking up the clot in the brain. However, in order to have this effect, it has to be given within 3 or 4 hours of the stroke. Also, it is risky and not appropriate for everyone, and some strokes are caused by bleeding not clotting, in which case TPA would be fatal.