One of the reasons people love Wolverine is his mutant ability to quickly heal from any injury, known as his healing factor. It basically means his cells grow so fast that any cut or wound is healed within minutes if not seconds. While there are other superheroes and supervillains in the Marvel Universe that can heal quickly, no one else does it like Wolverine.

RELATED: For Your Health: 15 Heroes You Forgot Have Healing Factors

2017's "Logan" is set in a future where Wolverine has grown old and his healing factor is failing, showing how vulnerable he is without it. While you might know his power lets him take a lot of punishment, you might not know all the things his healing factor can do and what it can't. CBR decided it's time to review 15 things you didn't know about Wolverine's healing factor.

15 IT GOT STRONGER

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When Wolverine was introduced as a regular member of the X-Men in 1975's "Giant-Size X-Men" #1 (written by Len Wein and penciled by Dave Cockrum), his healing factor wasn't the powerhouse we think of today. He could still be hurt, and it would take hours, days or even months to recover from serious injuries. Over time, as his popularity increased, his healing factor grew more and more powerful. One of the high moments came in 2003's "Venom" #8 (Daniel Way, Francisco Herrera) where a nuclear bomb was dropped on Wolverine and he regenerated within seconds.

An explanation was given in 2011's "Wolverine: The Best There Is" #4 (Charlie Huston, Juan Jose Ryp) for how his healing had gotten so fast. It said Wolverine's healing factor had adapted to decades of injuries, getting faster and more efficient. Just like a muscle gets stronger the more it's used, Wolverine heals quicker the more he gets hurt.

14 IT CAN BE STOPPED

Wolverine wields the Muramasa Blade against Daken

Along with his adamantium skeleton, Wolverine's healing factor is one of his best assets, which makes him almost indestructible. One of the first rules of fighting Wolverine is to try to stop his healing factor, and there have been a lot of different ways to do that in the comics. One way is with carbonadium, first introduced along with Omega Red in 1992’s “X-Men” #4 by John Byrne and Jim Lee. Carbonadium was the Soviet Union's attempt to duplicate adamantium, leaving them a strong (but not unbreakable) metal that drains a mutant healing factor.

Another way is with a unique sword known as the Muramasa Blade. The second version of the blade appeared in 2006's "Wolverine" #37 (Daniel Way, Javier Saltares), made from part of the soul of Wolverine. It could cut through anything and also stopped the healing factor of Wolverine and other mutants. Wolverine most recently used it to cut the head off his archenemy and fellow mutant Sabretooth.

13 IT STOPS DISEASE

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In 2001's “Origins” (Bill Jemas, Paul Jenkins, Joe Quesada, Andy Kubert, Richard Isanove), we saw the young James Howlett as a sickly young boy, but when his powers manifested, he got much healthier. That's apparently when his healing factor kicked in, because Wolverine was rarely sick again. His healing factor normally protects him from any bacteria or viruses that try to infect him, even including allergies.

The only way to infect Wolverine is with a disease that can bypass his healing factor. In 2013's "Wolverine" #7 (Paul Cornell, Mirco Pierfederici), he fought an intelligent virus from the microscopic world of the Microverse, which tried to infect the world. It infected a S.H.I.E.L.D. helicarrier and its crew, and wanted to infect Wolverine. As a last resort, the virus had one of its hosts shoot Wolverine with a bullet loaded with itself. Logan's healing factor stopped the infection, but burned out in the process, its final revenge for a failed mission.

12 IT STOPS POSSESSION

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The healing factor doesn't just protect Wolverine from injury and disease, it also makes him really hard to possess or convert by other creatures. Anything that tries to turn him into something other than Wolverine is reverted by his healing factor, and many have tried. For instance, in 1982, "Uncanny X-Men" #155 (Chris Claremont, Dave Cockrum) introduced a parasitic alien race called the Brood that tried to infect Wolverine along with the other X-Men. He was able to resist them, thanks to his healing factor and adamantium skeleton.

In 2011’s “X-Men” #5 (Victor Gischler, Paco Medina), vampires invaded San Francisco, and Wolverine was bitten by an infected Jubilee. He changed into a vampire, but it turned out the X-Men had injected Wolverine with nanobots to burn out his healing factor. When they turned off the nanobots, Wolverine's healing factor reversed the effects of the vampire bite and turned him back to normal.

11 THE LAW OF CONSERVATION

Wolverine Dave Finch

Whenever Wolverine is injured or has parts of him cut off, he has to grow back his muscles, blood and skin quickly. The question has come up, how does Wolverine have the energy and body mass to rebuild himself so fast? It's the law of conservation: energy and mass can't be created or destroyed. If someone just cut out Wolverine's spleen, he has to build a new one out of something. Readers have also been asking the question of whether Wolverine can eat himself to keep from starving to death, as he claimed to Jean Grey he once did.

Well, for one thing, Wolverine eats a lot. He doesn't have to eat tons of food like the Flash, but if he's deprived of food, he could weaken from hunger and stop healing. It's also been suggested he might tap into another dimension for his added weight. That's not as crazy as it sounds, because Marvel has said the Incredible Hulk and Ant-Man do that when they grow quickly. Imagine another universe filled with meat, and Wolverine just drains some of that into himself. Gross, but cool.

10 INSIDE JOB

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When Wolverine is stabbed or shot, his body heals quickly around the wound to seal it, and sometimes it heals a little too quickly. In the "X-Men" movie series and his own trilogy, we saw Wolverine get shot, and the bullets being pushed out of his body. That doesn't happen in the comics, where we've seen multiple times what happened when foreign objects stayed in him... and it's not pretty.

When Wolverine is stabbed with a knife or a spear, he heals around the blade, leaving it stuck inside him. He ends up having to literally rip the blade out of himself. As Wolverine himself said, it's worse when he heals around bullets. If the wounds are still fresh, he has to reach into the gaping hole and fish the bullet out. If not, Wolverine has to cut bullets out of his body, racing to get it out before his flesh heals around his fingers. Not a pretty sight.

9 IT SLOWS AGING

Alternate Wolverine Old Man Logan

The definition of "healing" is kind of vague, and Wolverine's body takes a broad view of it. For instance, the normal process of aging is something his healing factor doesn't take kindly to. What we think of as growing old is really a gradual breakdown of the cells, and his healing factor grows cells more quickly, making Wolverine someone who ages very slowly.

"Origins" established that Logan was born in the late 1800s, making him over 200 years old, but he looks like a man in his prime. No one really knows how long his healing factor will let him live or when he will start to show his age. X-23, who's younger than him and without his adamantium skeleton, claims she heals faster than him. 2009's "Wolverine: Old Man Logan" (Mark Millar, Steve McNiven) showed a distant future where Wolverine has grown old and grey, and Old Man Logan has been brought into the mainstream universe, but that's from an alternate reality.

8 IT CAUSED AMNESIA

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Another area where Wolverine's healing factor has moved into is his memory... or lack thereof. Wolverine has had a hard life, from his childhood where he watched his father murdered in front of him, all the way up to being sent to Hell by a group of disgruntled relatives of his victims called the Red Right Hand in 2010's "Wolverine" #1 (Jason Aaron, Renato Guedes). Along the way, every woman he's ever loved has either died or been murdered, and he's undergone countless experimentation and torture.

Up until the crossover event "House of M," Wolverine didn't remember most of it, partly because the Weapon X organization erased his memory. It was also revealed in 2002's "Wolverine"#175 (Frank Tieri, Sean Chen) that his healing factor considered his bad memories a form of injury and caused amnesia to protect him from them. It's pretty crazy to think his own body looked at his life and said, "Yeah, he's better off without that."

7 IT STOPS POISON

Wolverine and Shingen battle it out

Another thing that Wolverine is immune to thanks to his healing factor is poison. His healing factor protects Wolverine from poisons that would kill a normal human being. This came up in 1982's mini-series “Wolverine” (Frank Miller, Chris Claremont),which took Logan to Japan to try to win his lost love, Mariko Yashida. Her father challenged him to a duel with practice swords to humiliate him and make Mariko reject him. Just to make sure, before the fight, Shingen had Wolverine hit with a poisoned shuriken that would have killed a normal person many times over. The poison only weakened Wolverine, enough to slow his reflexes and make him lose the fight.

His healing factor also keeps him from getting knocked out by drugs or even getting drunk, since alcohol is technically a poison, but that doesn't stop Wolverine. He drinks massive amounts of alcohol that would kill a normal human just to get a slight buzz on.

6 NO PSYCHIC ATTACKS

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Another benefit of his healing factor is that Wolverine is protected from psychic attacks. His healing factor seems to think of psychic powers as a physical threat like any other, so Wolverine has found what he calls "mental scar tissue" from all of the horrible things that have happened to him over the course of his life. That, plus some really strong mental shields put in his mind by Professor Xavier, mean anyone who tries to control or read his mind is out of luck.

The combination of his healing factor and shields mean Wolverine's mind stands up to telepathic assault and probing. In 2009's "Wolverine" #46 (Marc Guggenheim, Humberto Ramos), even the powerful psychic Emma Frost couldn't penetrate his mind. That comes in handy, because the X-Men fight a surprisingly large number of telepathic supervillains. While the other X-Men are getting their brains scrambled, Wolverine keeps slicing. His brain is as strong as his bones.

5 STAMINA

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One other way his healing factor protects him is from getting worn out in battle. When Wolverine is swinging his arms, hacking people up, he doesn't start gasping for air and collapsing anytime soon. That's because his healing factor breaks down lactic acid that would normally build up in his muscles. That doesn't mean he never gets tired, because he does need sleep. What it means is that when Wolverine goes into "berserker mode" in a fight, he's stronger, faster and can keep going longer than a normal human.

A great example of that came In "X-Men" #5 (Jim Lee, John Byrne) when Wolverine fought the Soviet super-soldier Omega Red. Omega Red's carbonadium tentacles tore into Wolverine (despite his healing factor) enough for him to actually go toe-to-toe with the Ol' Canucklehead like never before. The two of them were locked in a fight for 24 hours straight, and neither one of them passed out from exhaustion.

4 ADAMANTIUM POISONING

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We should clarify that Wolverine is vulnerable to a very specific poisoning, and that's adamantium poisoning. When Weapon X experimented on him to bond the indestructible metal to his skeleton, they might have chosen him because his healing factor allowed him to survive the procedure and the aftermath. The metal is really toxic, and the amount inside Wolverine would have killed a normal human long ago.

In fact, Wolverine's healing factor would work a lot better without the adamantium. When Magneto ripped the metal out of Wolverine's body in 1993's “X-Men” #25 (Fabian Nicieza, Andy Kubert), Logan's healing factor increased exponentially. When Wolverine's healing factor was burned out, Beast needed to create an agent for him to take to stop the metal from killing him. It seems like the mysterious disease that was killing him in "Logan" was adamantium poisoning, meaning his healing factor finally lost the war against the powerful metal.

3 DROWNING

Now that we've talked about all the things his healing factor can heal him from, let's talk about one thing it can't: drowning. While the list of things Wolverine can survive is long, being trapped underwater isn't one of them. Unlike a lack of food, Wolverine can't "heal" from a lack of air. If he's drowned long enough, he'll die.

Wolverine suggested early on that this might be the case in early stories, because his metal skeleton weighs him down, and it was referenced in 2013's "Wolverine" #6 (Paul Cornell, Mirco Pierfederici) in a two-part story arc called "Drowning Logan." In the arc, Wolverine was trapped in a helicarrier deep in the ocean when it was flooded, forcing him to swim for 15 minutes straight. While his healing factor kept him from being crushed by the water pressure, his lungs collapsed and he almost died. Then there's the fact that Wolverine was able to kill his vengeful son Daken, who also benefits from a healing factor, by holding him face-down in a puddle until he drowned.

2 ANGEL OF DEATH

Wolverine vs Azrael in world war one

A lot of people say it's Wolverine's healing factor and adamantium skeleton that make him invulnerable. While the healing factor is powerful, it's not the real secret of his long life or what's kept him alive for centuries. As we mentioned earlier, Wolverine has faced death many times, including in the form of a nuclear bomb. It turned out his healing factor wasn't what brought him back to life, but a deal with the literal Angel of Death.

In 2007's “Wolverine” #57 (Marc Guggenheim, Howard Chaykin), Doctor Strange discovered that Wolverine's soul had been damaged. It turned out that during World War I, when Logan had been fighting on the battlefield, he came close to dying and faced a mysterious stranger who he fought and won. The stranger was Lazaer, the Angel of Death. Ever since, when Logan was hurt to the point where his healing factor failed, he fought Lazaer in Purgatory to return back to life. To heal his soul, Wolverine offered his death in exchange, leading to the final death of Wolverine.

1 HEALING COPIED

X-23 Wolverine

When Wolverine was kidnapped by the Weapon X program, they subjected him to horrible experiments to graft adamantium onto his bones, torture and brainwashing. He escaped the program, but he became the ultimate warrior and they've been trying to copy their success with him ever since. Besides duplicating his adamantium, Weapon X managed to save some of his DNA, and have been trying to use it to implant his healing factor in others.

Over the decades, they've used his DNA and grafted it into different superheroes like Deadpool and supervillains like Garrison Kane (also known as “Weapon X”). Unfortunately, a lot of the experiments have failed or produced side effects, like Deadpool's disfigurement. At one point, the Weapon X branch known as the Facility tried to clone Wolverine, producing (as shown in 2005’s “X-23: Innocence Lost” by Craig Kyle, Christopher Yost, Billy Tan) the female clone, X-23. She has his healing factor, and became the new Wolverine when he died.

What would you do with Wolverine's healing factor? Let us know in the comments!