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Joker Venom is the Joker's signature weapon. Joker Venom is a toxin, usually dispersed as a gas that makes victims laugh uncontrollably. The Joker himself is immune to the effects of Joker Venom after prolonged exposure to it.


A 1996 Fleer OverPower collectible game card

Lethal version

Contact with Joker venom causes uncontrollable spasms of laughter, followed by a painful death. Some have speculated that the venom hyper stimulates the laughter functions of the brain, leaving the victim unable to breathe. It is also possible that this drug contains tetanus toxin (also known as lockjaw). Patients often exhibit a grotesque grinning expression called "Risus Sardonicus" due to spasms of the facial muscles (CN VII). Mortality often follows this clinical presentation. 

Non-lethal version

The venom causes uncontrollable laughter (as if one just heard a very funny joke or saw something that they perceived as hilarious), but instead of dying, their faces are usually pulled into an unusually large grin. Artists often stylize the effects, adding yellowed teeth, bulging eyes, paleness etc. similar to the features of the Joker himself.

Prolonged exposure to the non-fatal forms can cause permanent brain damage.


Joker Venom has had a variety of names depending on the writer. They include: Smilex, Smylex, Laughing Gas, Joker Gas, Happy Gas, Giggle Gas, Joker Juice, Laughing Toxin, Laugh-A-loads, Perma-Smile, Smiley Gas, and Joker Toxin.

In Other Media


Batman: The Animated Series

Joker venom is used frequently in the animated series, and its spin-offs such as Batman: Mask of the Phantasm. The most popular use of it in the animated series is through a "Very Special Flower" on The Joker's purple suit. In Batman Beyond: Return of the Joker, The Joker used this on an elderly Bruce Wayne after ambushing him at the Batcave. During the series the non-lethal version was more often used, due to the fact this was a children's program. Though the lethal version was occasionally used, with the victims often getting an antidote in time. Effects of the toxin presented within the show varied from stretching faces into smiles to simply causing uncontrollable laughter until the toxin wore off or an antidote was given.

The Batman

Both versions of the venom are used in this series. The non-lethal version is weaponized as a gas and seems to dissipate over time. The gas is called "laughing gas", and puts its victims into a coma. Batman provided an antidote to this laughing gas. However, Joker also has a lethal version which is a liquid. The effects of this venom are the same as the one used in the Joker's first appearance in the comics (a venom which takes 24 hours to kill). In the meantime, the victim slowly has increasing bouts of uncontrollable laughter until they are unable to breathe and die. Batman was once infected with the venom, but was able to create a cure before it was too late. Penguin was infected as well although he was cured offscreen. These two characters are the only ones we eve see infected with the lethal venom. The lethal venom is also explosive, as shown in "The End of the Batman", where Wrath and Scorn fall victims to it. However, it's not used to kill them but instead used to break their minds to prevent them from revealing Batman's identity, and therefore spoil Joker's fun.


The creation of the Joker Venom was covered in the fourth season of the prequel series Gotham. It was invented by Scarecrow on Jerome Valeska's orders, who later used it to drive his brother Jeremiah into madness.

Justice League Action

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Joker Venom appears in the show on several occasions..



The Joker uses "Smylex" specifically in gas form, in an attempt to kill everyone at a celebration in the center of Gotham. He also contaminates household products with binary compounds of the chemical, which is only lethal when mixed together the right way.

The Dark Knight

Joker Venom does not appear in the film, but Joker's preferred method of murder (carving Glasgow smiles into victims' faces and applying make-up similar to his own) might be a subtle reference. The novelization mentions that Hamlin, a private investigator hired by Maroni and the crime lords to discover his identity, was murdered with a poison that causes him to laugh hysterically to death. It is heavily implied to be derived from Scarecrow's Fear Toxin. Additionally, some have theorized that the gas grenade stuffed in the Gotham National Bank Manager's mouth contained Joker Gas and not harmless smoke.

LEGO DC Comics Superheroes: The Flash

Superman, Wonder Woman, Firestorm and Plastic Man uncontrollably laughing after getting infected by Joker Venom

During a vacation in Metropolis, Joker uses his Joker Gas to make the citizens of Metropolis laugh to death. Firestorm and Superman are about to get the Joker, but Joker’s blimp popped behind them, and they get infected by the Joker Gas. After taking down Joker’s Robo-clowns, the villain fakes giving up and tricks Plastic Man and Wonder Woman into having a photo, making the two heroes infected by Joker Gas. Cyborg (who hasn’t been infected by Joker Gas) is still putting his body parts back together after getting electrocuted by Joker’s Joyshocker bomb on the Javelin, watches as the Daily Planet gets jokerfied, saying This does not look good, Joker says that its hilarious making Superman, Wonder Woman, Firestorm and Plastic Man laugh even harder, Joker plans on staying at metropolis forever as his new vacation for eternity. Atom discovers the Joker Gas cure saving the citizens of Metropolis (and the Justice League) from laughing to death, ruining the Joker’s vacation. When stuck in a time loop, after The Flash snatches Joker’s Fun Cannon button, Joker is about to douse him with Joker Gas, but Batman stops him before Joker can do it.

Video Games

LEGO Series

Joker Gas is often used by the Joker in LEGO Batman: The Videogame, though always in cutscenes. In "The Joker's Return" plotline, he and his gang plan to destroy Gotham City with the gas, releasing it from Gotham Cathedral.

In LEGO Batman 2: DC Super Heroes, Lex Luthor recruits Joker to use his mind-control variant of the toxin to win the presidential election. The gas is spread through a giant Joker robot, though the despiser is eventually taken out by Batman and Superman.

Joker Gas also appears in LEGO DC Super-Villains, where it can be mixed several times by the Joker to bypass security guards and obstacles. To create the toxin, Joker must collect and mix a trumpet, a rubber chicken and a laughing fish.

Batman: Arkham Series

Joker Toxin is an obstacle for several areas in the video game Batman: Arkham Asylum.

In Batman: Arkham Asylum, Joker Venom (referred to in the game as "Happy Gas" by the Joker, "Smilex" by the canisters and "Joker Toxin" by others) appears as an obstacle in many areas in the game. In parts of the Asylum, Joker fills rooms with the Joker toxin, which requires Batman to vent them before proceeding. In the later game, Joker attaches some cylinders of the gas to several security controls. If Batman fails to correctly hack them in time, they release the toxin into the air and harm/kill him.

Joker Venom appears briefly in Batman: Arkham Origins, where it is used to kill the Gotham Merchants Bank Manager. Her contorted face is often shown haunting Batman throughout the game.

Background Information and Notes

Joker venom has been Joker's preferred murder method since his first appearance in Batman #1 (1940). Writer Bill Finger was directly inspired by an episode of the Shadow radio serial, The Laughing Corpse, which features a poison with the exact same effects. The venom is often deployed as an airborne agent, but can also be used in its liquid form (used both to poison victims through their unwitting consumption of it, or in special darts). With the poisoned Laughing Fish, the venom was injected into the fish then passed along into a cat to attack the target. The variant utilized with the former was implied to be non-lethal by Batman after doing a toxicology screening, as Joker intended to simply get it trademarked. In The Killing Joke, Joker uses a spike worn in his palm (similar to his Joy Buzzer) to administer the drug in a handshake. In Batman: The Man Who Laughs the Joker uses bullets laced with Joker Venom in order to kill another of his selected targets. In Jeph Loeb's and Tim Sale's Catwoman: When in Rome Joker venom is duplicated by the Riddler to blame Catwoman for the murder of a Sicilian Mafia kingpin. It is referred to as Joker Juice by both Catwoman and The Riddler.

In a 1980s comic book, the Joker facilitates one of his many escapes from Arkham Asylum using the venom - by mixing together the common cleaning chemicals found in a janitor's closet, showing his vast knowledge of chemicals yet again.

The DC Technical Manual: S.T.A.R. Labs 1993 Annual Report (a sourcebook for Mayfair's DC Heroes Roleplaying Game) stated that Joker Venom is "a hellish mixture of hydrogen cyanide and Strychnodide (a strychnine derivative), the toxin causes immediate cessation of heart and brain functions. As a side effect, the victim's muscles contract in such a way as to severely tighten and discolor the victim's skin, especially in the facial area. This leaves the victim's corpse permanently scarred with a clown-like grin in tribute to his killer. Since the Joker Venom is just as deadly if absorbed through the pores as it is if inhaled, the Joker occasionally releases it in gas form throughout the central heating/cooling vents of a building. How exactly Joker knows how to make the venom varies by story. In the graphic novel Batman: The Killing Joke, it was revealed that the man who would become the Joker once worked in a chemical plant, and may have had some chemical education as a result. The 2004 graphic novel Batman: The Man Who Laughs revealed that Joker, who was created by falling into a vat of chemicals, had stolen them in a plan to poison Gotham City's reservoir, but the plan was foiled by Batman. His brand of Joker venom turns the victim's skin white, hair and nails green (though he's been known to paint them red & black) and lips become ruby red. However, it appeared he went through stages to get the desired effect when the Police discovered a warehouse full of dead bodies all with white skin and green hair but on some the face muscles were so contracted that the eyes popped out and the skin tore apart. The perfected joker venom came in two varieties: a fast acting one used to kill a T.V reporter and a slow acting one to kill one of his victims at exactly midnight. Another kind of venom, as shown in an episode in The Batman, The Laughing Bat was a kind of venom which affects the victim's nervous system and causing them to break into fits of uncontrollable laughter, which would slowly kill them throughout a prolonged period of time.

A story arc in Batman: Legends of the Dark Knight revealed that a cousin of the man who became the Joker, Melvin Reipan (surname Napier spelled backwards, an autistic savant with a gift for chemistry, is persuaded to create the Joker Venom as a way to "make people laugh", in exchange for becoming "handsome". However, Reipan is in fact physically very attractive, only having been told by his abusive mother he was ugly. This story appeared in Batman: Legends of the Dark Knight #50 and not only revealed the origins of Joker Venom, but also told the first battle between Batman and the Joker after his first attempt to destroy the city.

In the story arc, Batman: Cacophony, a gang war between the Joker and Maxie Zeus erupts over Maxie Zeus cutting the Joker's venom with Ecstasy to make a new designer drug called "Chuckles".

Joker Venom and Red Dust composed of the same material.

Marvel Comics has an apparent equivalent to Joker venom in the form of Red Skull's "dust of death", a chemical which turns the head of its victim into a "red skull" resembling that of Red Skull. In a crossover, the Red Skull and the Joker face off against one another, the Joker got angry when he learned that he had unwittingly worked for a Nazi ("I may be a criminal lunatic, but I'm an American criminal lunatic!"), and employ their favorite toxins on each other. They realize the toxins are useless against each other, as both combatants are immune to their own, and both toxins are strikingly similar at a chemical level.


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