Kryptonians get their power from Earth's yellow sun, however when they are on a planet that has a red sun, they are essentially human.

Kryptonite was irradiated by Krypton's explosion, it's not affected by the radiation from the different suns. Green Kryptonite is deadly to Kryptonians due to the radiation it absorbed from the explosion, it doesn't remove their powers, it simply poisons them.

So with that said, if a Kryptonian were on Earth, full powers and everything, and the Earth's yellow sun was turned into a red sun, thus gradually 'turning' the Kryptonians into humans(I know they aren't transformed into humans, but they more or less share the same physiological attributes), would these Kryptonians still be affected by Kryptonite?


2 Answers 2



Kryptonite is lethal to power-less Kryptonians. Look at this tale of Agro City (which survived the Krypton explosion) from Action Comics issue #252 (Silver Age):

Agro City Kryptonite poisoning and shielding

  • What about the Silver Age Kryptonians and current versions of Kryptonians? Their exposure to Kryptonite didn't occur until it showed up on Earth, i.e Krypton never had Kryptonite.
    – Robert
    Commented Oct 31, 2014 at 16:13

Yes, with the idea that they are more or less human the effects are basically the same. The material emits a lvl of radiation that over time is unhealthy. Best example of this on an Earthling would be when (Post-Crisis)Lex Luthor develops cancer after constant exposure by way of directly handling the material. Specifically from wearing a kryptonite ring. Luthor has to have his hand removed and replaced with cybernetics.Superman vol.2 #19 (1988)

Kryptonite does dampen powers of super-kryptonians. Otherwise a sickly Superman would still be able to fly away while weak or retain more of his invulnerability. It reacts with the UV-powered cells in their body to create a rapid case of radiation poisoning. This is used to explain the repeatedly inconsistent affect on Superman,eg. where he is at the time/his power lvls/the rate & intensity of power dampening effects. The multi-verse origins of the person and the kryptonite need to be the same for maximum results.

Post-Crisis kryptonite only comes in one natural form:green. Birthed from the exploding planet,green kryptonite can be altered using cosmic rays to create variant forms with various powers. The example given in a previous answer of Action Comics issue #252 (Silver Age) is from the Pre-Crisis DC Universe.

  • Post-Crisis Kryptonite and the New 52 Kryptonite may have different effects. But this is because the New 52 is still unclear with what has and has not remained canon after the Flash Point event.
    – joeshmosan
    Commented Nov 10, 2014 at 12:30
  • So it would affect them in the way that it affects humans, it just basically becomes radiation poisoning? One thing I did find wrong with your answer though, kryptonite doesn't dampen or weaken a Kryptonian's powers, it affects the actual body of the Kryptonian. Which is why a Kryptonian can operate at 100% once it's out of the 10ft range. It doesn't affect their powers really, it's more along the lines of constant being injected with rat poison, it causes excruciating pain and eventual death.
    – Robert
    Commented Nov 10, 2014 at 19:01
  • @Robert From the Superman:Ultimate Guide to the Man of Steel.Scott Beatty.2002 phonepic
    – joeshmosan
    Commented Nov 11, 2014 at 7:22
  • expanded:From DCdatabase wiki(take it for what it is,if it was 100% we wouldn't be here)"Exposure to green kryptonite radiation will greatly weaken a Kryptonian, slowly robbing them of their powers as the Green K energy replaces the solar energy stored in a kryptonian's cells. It has been shown that an unpowered kryptonian (one with no yellow sunlight stored in their cells) is much more resistant than a fully powered one."Logically the K-nite would have to dampen powers because invulnerability is a power.Only a power lvl >superman or magic can harm him with his powers intact.
    – joeshmosan
    Commented Nov 11, 2014 at 7:39

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