Pre-Crisis

Blue kryptonite is the result of using Professor Potter's "duplicator ray" on some green kryptonite. Here, blue kryptonite affects Bizarro like green kryptonite affects Kryptonians. Blue kryptonite radiation is not blocked by normal lead, but by imperfectly duplicated lead. Bizarro World had animated blue-kryptonite golems underground that surfaced and attacked the superpowered Bizarros while the delighted non-powered Bizarros cheered them on.

Post-Crisis

• In Post-Crisis continuity, like Bizarro himself, Blue Kryptonite is opposite to the more common green variety--it will make Kryptonian-based Bizarros (see Batzarro) highly intelligent (up to 12th level intellect), a process that seems to scare Bizarro and his ilk.
• Post-Infinite Crisis, Blue Kryptonite appears to have reverted back to its original form as it has been seen (as of Action Comics Annual #10) to affect Bizarro in a painful manner reminiscent of the effect that Green Kryptonite has on Superman.

Other Media

Super Friends

In the episode "Terror from the Phantom Zone" blue kryptonite heals Superman from the effects of red kryptonite.

Smallville

Blue kryptonite suppresses Kryptonians' powers and removes their sensitivity to green kryptonite. Blue kryptonite was first introduced as a Victory Ring given to Clark by a replicant of his mother Lara in "Blue." Also in Smallville, Bizarro's powers were increased exponentially by blue kryptonite (this version of Bizarro being an 'inverted' Clark, weakened by sunlight and strengthened by green kryptonite) which overloaded his body with power and killed him, much like "a light bulb being powered by a nuclear reactor," in the episode "Persona."

In episode 7 of season 9, titled "Kandor," Jor-El is shown using blue kryptonite to remove the powers bestowed by Earth's yellow sun upon the Kandorian soldiers led by Zod as he prepares an orb which will carry to Earth the DNA clones of several of the Kryptonian capital's finest soldiers.

In the season 9 finale, titled "Salvation," blue kryptonite is used in the form of a dagger by Zod to rid himself of his powers, thus sparing him the trip to whatever planet the Kandorians were going to after Clark used the Book of Rao to save Earth from the coming war. A fight between Clark and Zod ensued whereupon Clark sacrificed himself: he allowed the dagger to be plunged into his gut and then fell from a rooftop, sending Zod to the planet and leaving Clark on Earth. The now powerless Clark is seen falling to the streets below. The aftermath of these events was not expected to be seen till the first episode of season 10, as it was a cliff-hanger.

In Episode 6 of Season 10, titled "Harvest", Blue Kryptonite is shown to purify water to the extent that humans drinking it do not become sick from common viruses. It also can be linked to improving crop production. Clark is unable to use his powers around people who have been drinking water contaminated by the blue kryptonite.

Justice League: Crisis on Two Earths

Blue kryptonite has the same weakening effect on Ultraman that green kryptonite has on Superman.