When Superman is exposed to kryptonite he becomes weak. What actually happens to Superman when he is exposed to kryptonite?

  • 16
    He becomes weak.
    – Zommuter
    Commented Oct 15, 2013 at 11:55
  • What I mean is whether superman's blood pressure increases or decreases drastically or his stomach starts aching or something else which actually weakens him.
    – user18957
    Commented Oct 15, 2013 at 13:29
  • Sorry, I just couldn't resist :P But seriously, you should add some more details to your question, e.g. what you just commented. I got under the impression that he basically gets a super headache...
    – Zommuter
    Commented Oct 15, 2013 at 13:31
  • I've seen some examples where he simply is decreased to human capabilities, and others where it's mere presence can kill him. I think usually kryptonite kills him but I'm not sure
    – childcat15
    Commented Oct 15, 2013 at 13:54
  • 1
    You talking about all types of kryptonite or just the green kind? Commented Oct 15, 2013 at 15:16

4 Answers 4


For the Too Long, Didn't Read folks:

A sufficient amount of green Kryptonite kills Kryptonians, completely dead in under an hour. Something the size of a walnut appears to be enough. The mechanics are never explained beyond disrupting the solar energy cycle which gives Kryptonians their power and then exposing them to a toxic dose of high energy radiation. Superman Vol. 2 Number 22 shows the death of the Phantom Zone villains.

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For those interested in a longer answer:

Canonically, Kryptonite came in a variety of colors but only one color was lethal to Kryptonians, green Kryptonite (shortened in the 1970s to Green K.)

  • Green kryptonite, composed of an as yet unknown transuranic element, emits a unique (but replicable with the right advanced technology) high energy radiation. Green Kryptonite is one of the few things that can weaken and ultimately kill a Kryptonian.

  • Immediate exposure within five to ten feet would immediate cause Superman to lose his powers, depending on the purity of the material.

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  • In addition to immediately losing his powers, he would weaken and visibly became ill. The exposure caused him great pain while reducing his ability to absorb solar energy.

  • Even in the presence of the sun, Kryptonite displaces solar radiation faster than Superman can utilize it. This makes it one of the most dangerous substances to a Kryptonian.

  • If left too long in the radiation of Green K, Kryptonians die from what would likely be considered a form of extreme radiation poisoning where they die in under an hour. They did not get the standard blistering or burns, but depending on the writers/editorial mandates took on a greenish cast when killed or dying from Green K poisoning (most often seen in the Silver Age comics.)

  • The more colorful forms of Kryptonite (and their powers) vary widely depending on the continuity. The above chart shows the effects of Kryptonite in the Pre-Crisis/Silver Age, DCU. In the modern DCnU, colored kryptonite is green Kryptonite exposed to various radiations altering its effects.

Green Kryptonite is localized to space-time its found in

  • All Green K was not created equally, as we discovered that Kryptonite from one continuum was not necessarily a threat to a Kryptonian from another space-time continuum.

  • In Superman Vol. 2, Number 22, Kal-El enters the pocket universe and discovers variants of the Phantom Zone villains who have killed five billion humans on that Earth. Though they had been depowered by Gold Kryptonite, they vowed to find a way to restore their powers. Unsure of they could regain their powers, Kal-El executes them with a local variant of Green K which was harmless to him.

Doctors don't talk about Green K, neither do editors.

  • Since writers don't tend to be scientists and comic companies don't tend to make a habit of writing medical treatises on their metahumans (though they should) we are never given the absolute physical specifics of how or why Kryptonite works.

  • We know it displaces his internal solar radiation stores, stealing his powers away almost immediately. It has been used as a surgical tool as part of a kryptonite scalpel giving surgeons the ability to operate on his invulnerable body.

  • We know Kryptonite comes in a variety of levels of radiation and even less pure varieties (such as the one worn by Lex Luthor as a ring) took a considerable amount of time before it gave him radiation poisoning. So while the radiation in any amount is lethal to Kryptonians, it still takes some time to affect Humans.

  • We also know it is capable of acting as a power source for suits of powered armor. Both Luthor and Metallo used it (in previous continuities) to power their weaponized armors and mechanical bodies as a primary source of power. However, when utilized in this fashion, the Kryptonite seems less effective except at extremely close range. Perhaps the suits/armors draw more of the radiation for use (which makes sense) and the villains use it as a means of keeping Superman away from them during a conflict.

  • We also know, the signature of Kryptonite radiation can be emulated with advanced technology. The ring of a Green Lantern, can create an energy signature similar to green kryptonite which can weaken Kryptonians. We assume the Guardians included that energy signature in the Oan database as a failsafe in the event the Green Lantern Corps ever needed to apprehend, contain or even kill a Kryptonian.

  • Excellent answer, and +1. Why would you need to operate on someone who is invincible? Doesn't the invincibility prevent disease, foreign body penetration, etc?
    – Wad Cheber
    Commented Jul 26, 2015 at 2:28
  • @WadCheber even superman gets broken bones sometimes. See his fights with Doomsday, another kryptonian. So it makes sense he could need surgery at some point.
    – Marvel Boy
    Commented Jun 6, 2018 at 18:27
  • And a Kryptonian has no special immunity to magic attacks. The blow from a magical musclehead could mean a trip to the E.R.
    – Blaze
    Commented Apr 27, 2019 at 21:02

Seems similar to radiation poisoning. From the Superman Wiki:

Some issues of Superman have indicated the mechanism by which green kryptonite may hurt Superman. Like Hanna-Barbera's Birdman, Superman in some ways is a living solar battery; his cells absorb electromagnetic radiation from stars (like Earth's sun). Kryptonite's radioactivity possibly interferes with this process, driving the energy out of his cells in a painful fashion. Long term and high-level exposure to green kryptonite can be fatal to Superman. In post-Crisis comics, long-term exposure to kryptonite is known to have the same effects on human beings as exposure to Earth-born radioactive materials; these effects include cancer. Lex Luthor discovered this inadvertently after acquiring a ring with a green kryptonite fragment set in it to provide protection against Superman—Luthor first lost the hand he wore the ring on to cancer and later had to have his brain transferred into a new, cloned body after the cancer was found to have spread throughout his original body.


Superlative answers! I should wish to add some notes, too, which weren't discussed.

Now, I have been a Superman fan for well over 20 years, and have seen the effects of Green K on Kryptonians in a variety of media, so I'll be drawing a few examples. As we know, the overall effect of green Kryptonite is high level toxicity to Kryptonians. However, these effects can vary based on a few factors. These are:

  1. Amount/Mass of the metal/ore
  2. Purity of ore
  3. Duration of exposure/Concentration of radiation
  4. Universe/Dimension in which this is taking place
  5. Condition of the Kryptonian in question.

Because many of the basics and finer points have already been touched on, I'll try not to be repetitive and answer only the specifics listed, citing examples where I can or where necessary.

Generally speaking, Green K typically has the noticeable effects of

  • General physical weakness
  • Loss of energy
  • Some form of physical sickness or illness
  • Pain upon contact with the metal or a focused amount of energy there of
  • Increased vulnerability to Kryptonian tissues
  • Symptoms similar to low level radiation poisoning
  • Loss of fine motor control
  • Dizziness

It has been stated that Green K's detrimental effects are caused on a cellular level; it acts as an ionizing radiation [one of the only types Kryptonians seem to be vulnerable to] which effectively destroys some of their molecular bonds. This makes sense, as a portion of Superman's powers are derived from the non-ionizing radiation of the sun, and cellular destruction would result in the release of that energy which his body uses as enhancement fuel. Another aspect to Superman's strength has been stated to be his molecular density, thus effecting those bonds would result in making him weaker physically. Lex Luthor in the 1978 Superman film stated [or theorized]that it was a "specific radiation" of Kryptonite which would essentially be "keyed to" the cellular structure of denizens of that galaxy, basically effecting their cosmology, which is why it would be lethal to them, but not other beings.

Prolonged exposure, depending on circumstances, can have other notable physical effects such as unconsciousness, bruising, lacerations and the kryptonian's skin turning green.All of these can vary depending on the following.

Amount/Mass of Metal/Ore

This would seem to be an important factor, according to most versions. Whether this is due to Kryptonian cellular structure or not is uncertain, but while small amounts of green-k can cause him immediate pain and some loss of physical power, death may seem to be avoidable. The 1996 Superman: The Animated Series "A Little Piece of Home" had Lois drop a roughly coin-sized fragment of green K into Clark's hand; no immediate weakness was evident, but he reacted with pain and dropped it. There was, however, no bruising, lacerations or other mark of injury. Later in that same episode, Superman was locked in a museum with a piece of green K roughly the size of a softball, and fighting a giant robotic dinosaur for several minutes. While his powers were weakened, and we would later find out he seemed to actually bleed, he was still conscious, moving, and possessed of all his faculties.

It should be noted that no lacerations or cuts were seen on Superman at this time-----and this iteration is notoriously for being physically weaker than most---- yet he and other Kryptonians in the DCAU have been exposed to vast amounts of Kryptonite, for minutes at a time at some points, with only general pain, weakness, sickness, dizziness and occasional unconsciousness resulting. They seemed still able to use their powers, but whether this was through a biological condition or a sheer force of will is unknown.

Purity of Ore

This also seems to be a variant factor, seem most notably in the 2001-2012 Smallville series. Several variants of Kryptonite [Green, Red, Blue, Violet, Black and White] were shown to effect Clark specifically, and aside from the first two, in ways distinctly outside that of established cannon. However, in this series, Green K specifically was seen to have a range bio-enhancement and mutagenic affects on human beings and other creatures as well. The exact effect varied depending on the vector of absorption, and somewhat on circumstance.... more on that later. Generally, however, Green K of this world was far more abundant and way more potent in effects. This was due largely to vast quantities of the raw ore seeding the town of Smallville in a meteor shower sometime in the 1980s.

The effects of Green K on a teenage Clark were notable, and usually immediate; proximity of about 3 feet with with a mass of ore roughly the size of a silver dollar could cause him immediate weakness, dizziness, headaches, sometimes nausea, and even fainting after several minutes. It was noted that as soon as it was out of that range, he would recover almost immediately, however. These effects lessened in potency as he got older, and Clark could stay around the "meteor rocks" and would not totally lose his powers, though he would only be able to utilize them with difficulty. Due to the abundance of the mineral, it would often be weaponized by others, in the form of arrows, bullets, and blades; Clark and other Kryptonians could be wounded and hurt by these weapons, but once it was non-fatal, they would recover quickly when out of range of the radiation.

Humans who had been "meteor infected" however rarely were able to be cured, with many developing metahuman abilities; everything from telekinesis, to teleportation, to pheromone control. Most notable would be one girl who ate vegetables from a garden seeded with green K and developed a monstrous metabolism, needing to draw mass from other humans to survive; a boy who was bitten or stung by dozens of Kryptonite infused bugs, and developed bug-like abilities including molting his skin and enhanced strength; students who inhaled vaporized K and received superhuman strength and speed enhancements; and another whom somehow fell into a coma near a cache of green K, and developed the ability to astral project into the body of others. The exact nature of these mutations is unknown, but it should be noted that even with the presence of the mineral in their bodies, Clark was mostly unaffected being near them. As such, we can deduce that the purity of the ore itself was diluted when it mixed with their physical chemistry.

Duration of exposure/Concentration of radiation

Evidence for this has already been provided from the previously mentioned shows, but for variance and further evidence, I'll turn to the CW's Supergirl Series. Within the first season, we see Kara, the biological cousin of Superman with a matching Kryptonian DNA and cellular structure, exposed to Kryptonite several times; its one of the few weapons the government agency she works for keep in check. Like in Smallville, they have developed several lethal weapons to use against hostile Kryptonians, who exist in this world. However, they also developed a special training area for Kara, which uses "low level Kryptonite poisoning" to not incapacitate her, yet negate or nullify her powers, most notably her strength and invulnerability. In this way, Kara has been shown to fight on par with skilled humans for upwards of 3 hours at a time. It should be noted that the Kryptonians of this world seem to be much weaker, slower and less durable than those of the Donner films or Smallville universe, but the effect is the same.

Secondary evidence of this can be seen in 2006 Superman Returns movie, with elements taken from the first two aspects; in that film, Superman lands on an artificially created continent made by Lex Luthor, which was created via Kryptonian crystal technology, which was corrupted by Kryptonite. Superman showed no discernible signs of sickness or weakness while being on this landmass for several minutes, until a bead of sweat ran down his brow. Only after an extended period of time on impure Kryptonite island was his strength and invulnerability shown to be taxed to the point where he was vulnerable, but not injured, by being beaten by a group of hired thugs. Luthor then produced a pure Kryptonite shank and stabbed superman in the back, breaking off about 3 inches of it in Superman's body. Superman was beaten, fell from several stories into rough water, and was still able to move and think consciously.

Two inches of the shard were removed and Superman regained total consciousness, retaining enough power to fly into the upper atmosphere for under one minute to recharge/boost his powers. He then flew underneath the landmass, used his heat vision and strength to cut it away from the earth and then, with only some difficulty, lift the island on his shoulders, with millions of gallons of water coming off of it, and fly it out into space and toss it away from the earth. Keep in mind this land mass was the size of at least a large island, if not a state, BTW---and compose at least partly of the one thing that weakens his strength! Superman then fell back to earth, impacted it hard enough to leave a crater, and was only unconscious for a day or so.

It was later revealed that while doing this, he still had about an inch or so length of green-k in his body from Luthor's shank. This shows, if somewhat inconsistently, that the amount of time Superman is exposed to the element, as well as its concentration, is a factor in how much of its radiation he absorbs and how it affects him. Even with a limited amount of pure green-k still in his body, however, there was not enough pain or weakness to stop him from using his powers to lift a landmass into space and survive reentry.

Universe/Dimension in which this is taking place

This is not the same point as made by an earlier poster about Kryptonite from "one continuum was not necessarily a threat to a Kryptonian from another space-time continuum." It's more about the given medium's Universe in which the story takes place. The 1978 superman [what I call the "Donner-Verse"] is different from the DCAU, which is different from the Ruby-Spears' 1988 Superman Universe, which is different from the Smallville-Verse, which is different from the Arrowverse. All of these "worlds" seem to show affects of green k on Kryptonians differently. For example, in the 1993 Lois & Clark series, the first time Clark was exposed to Kryptonite, it was a basketball sized amount, and he blacked out and lost his abilities for more than a day; all subsequent exposures only weakened him to a lesser extent and he never totally lost his powers again, though it did take him more time than usual to recover or "get his strength back" than any other version. Concurrently, this version of Superman could be directly exposed to a chunk of Kryptonite for several hours or put into a green K powered cage for an extended time and not die.

It could be that Kryptonians are different depending on which world they are portrayed in ---just as some version show Clark's powers as completely solar derived, while others attribute at least part of it to variances in gravity and evolution----- or it could just be plot inconsistencies. This would be supported by the last incarnation we saw of Superman on the big screen in Batman V Superman; Lex Luthor noted that the element caused "instant degradation within the Kryptonian cells" on the Zod corpse, and it seemed to limit or cut some of Superman's powers...however, there was no real instances of "pain" shown, accept where the ore was applied directly as a spear. What was given evidence was the weakness Superman had when he breathed in the gas and it saturated his cells, but even that was only for a limited time; while fighting with Batman and still using some of his strength, he recovered from his first exposure within a few minutes.

Condition of the Kryptonian in question.

As previously shown, if green K is effective by "driving out the solar radiation from Superman's cells," then this could be mitigated if his cells are full, over, super charged, or if he has been affected by some outside, nullifying element. In the 2000 DCAU movie Brainiac Attacks, Superman traveled into the Phantom Zone to retrieve a rare element to cure himself and Lois Lane of a unique form of Kryptonite poisoning which Braniac had developed to remain within his cells. This green K version was potent in some ways, and lacking in others; though it did cause harm to Superman, it did not take away his powers, merely limited them for a longer period after exposure [several hours it seemed] and it was lethal to humans who were exposed to a direct dosage via an energy wave. Upon finding the element stream, Superman was completely healed and re-energized instantly, and he was immune to it a second time. He also brought back enough to heal Lois with one tablespoon sized dosage.

One more thing to note is that in the previous Post-Crisis DC universe, in the 1996 story Kingdom Come, it was outright stated by a [then] future version of Lex Luthor that "green K just doesn't have the same punch on him" anymore. This is a [possible] future of the DC universe where Superman was in his late 50s after a major world war. Luthor himself attributed this to Superman's natural cellular development and time under the yellow sun; either way, he implied that green k could slow Superman down a bit, but was no longer lethal to him. These two instances, along with showing green k as ineffective at all against the Ultra solar charged All-Star Superman, show that a Kryptonians's condition can and does effect how potnet Kryptonite can be against them. This can thus effect all the other variables shown on this list, including the symptoms they feel.


Generally speaking, I theorize that Kryptonite poisoning to Superman is very much akin to either Chemotherapy or radiation treatment to cancer patients. The physical effects of cellular breakdown seem to be the same, and the symptoms....fatigue or weakness, nausea, pain, possible blistering/burning... or low level radiation poisoning. The reason it isn't lasting is that, like any normal human, Superman's body has a capacity to heal itself and recover after. Naturally, within a Kryptonian this capacity is likely more advanced, comparatively. Added to that his super-enhanced healing factor under a yellow sun and resistance to most types of radiation in general, and its clear that it will take a major exposure for an extended period to put down even the most average Krypton Terran.


I don't have any numbers or scholarly research to back this up, but based on my memory of extensive reading of silver age comics featuring Superman:

There seems to be a hierarchy of effects that Kryptonite has on Kryptonians.

The most immediate effects are pain and paralysis. Even a rather small chunk of Kryptonite will cause Superman (or presumably any other Kryptonian) to exclaim "Argh -- Kryptonite!" and stop him or her in his or her tracks.

Though pain and loss of mobility seem to be the most immediate effects of Kryptonite exposure, other super powers seem to last a bit longer. For example, Superman once saved himself from a chunk of Kryptonite (placed on his chest with him in a supine position) by barely managing to roll over, causing the approximately volleyball-sized piece of Kryptonite to roll off of him and roll away several inches. (It was a roughly spherical piece of Kryptonite.) He then used his Heat Vision to burn a hole in the ground. As the hole got deeper, the Kryptonite rolled farther and farther into it, increasing its distance from Superman, allowing its effects to diminish to the point where Superman could escape from it.

Once in a Silver Age story Braniac trapped Superman and Supergirl in a cage with Kryptonite bars, leaving them there to die. But since Supergirl was slimmer and smaller than Superman, she was actually able to slip between the bars and get away from the cage. Presumably she then recovered from the Kryptonite poisoning and found a way to rescue Superman. I suppose it was very painful and difficult for Supergirl to drag herself between the Kryptonite bars and escape, but I also suppose the pain and effort were preferable to being killed.

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