Contact with Joker Venom causes uncontrollable spasms of laughter and then causes a painful death. Some have speculated that the venom hyperstimulates the laughter functions of the brain and the victim is unable to breathe. It has been shown that the Joker is also capable of making Joker Venom that does not kill, or that kills much slower than normal, but with some notable exceptions he rarely uses these adaptations.
The S.T.A.R. Labs 1993 Annual Report states 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."
Joker Venom has been a part of the Joker's arsenal since his first appearance in the 1940's. The venom is often deployed as an airborne agent, but can also be used in its liquid form (used both to poison victims through consumption of it, or in special darts). In The Killing Joke, The Joker uses a spike worn in his palm (similar to a Joy Buzzer) to administer the drug in a handshake. Most notably, during the Joker's Last Laugh storyline, the Joker used an altered form of his venom to change the world's most dangerous supervillains in Blackgate Prison into "jokerized" versions of themselves, then set them amok on the world.
The Joker is capable of making Joker Venom out of nearly anything, once even escaping from Arkham Asylum by creating it with chemicals he found in a janitor's closet.
After his year long absence from Gotham, the Joker began using a new variety of Joker Venom that left victims with a frown instead of a grin. He used this variety on the GCPD officers while he retrieved his face.
He is also immune to his venom, it has been said, "being an avid consumer of his products, Joker's immunity to poisons has been built up over years of dedicated abuse."
- The Joker's Body Count
- Scarecrow's Fear Toxin
- The Red Skull's "Red Skull Dust" at the Marvel Database.
- Ace Chemical Processing Plant
- Joker Venom has also been used in other capacities. Maxie Zeus was known to have diluted it and mixed it with Ecstasy, marketing it as a drug called "Chuckles" which became popular at raves. Times Magazine referred to Chuckles as the worst drug epidemic since Crack in the late '80s.
- The Tim Burton-Joel Schumacher Batman movie franchise refers to it as Smylex, which is the name later given to a brand of toothpaste in the Tim Burton-directed Charlie And The Chocolate Factory.