I Got a Pocket Full o' Love
Created from Green Kryptonite that passed through a mysterious red-hued cloud en route to Earth. Red Kryptonite inflicts random effects on Kryptonians, typically creating an initial "tingling effect" in those affected. Each specific chunk of Red Kryptonite has the same effect on all Kryptonians, but no two chunks have the same effect as one another. Red Kryptonite effects typically last for 24-48 hours (though sometimes as long as 72), after which the Kryptonian in question is forevermore immune to that specific chunk of Red Kryptonite. Superman has suffered the following effects upon exposure to various pieces of Red Kryptonite: being turned into a dragon, a non-powered giant, a midget, an ant-headed humanoid, a lunatic, or an amnesiac; growing incredibly long hair and beard; being rendered totally powerless; losing his invulnerability along the left side of his body; being split into an evil Superman and a good Clark Kent; rendered unable to speak or write anything but Kryptonese, the language used on Krypton; growing an extra set of arms; and rapid aging.
(via John Lanning. The Superman Homepage