Warning: Extremely graphic photos. Viewer discretion advised.

Russia’s "krokodil," also known as Crocodile, is a lethal drug, and has been referred to as the "zombie apocalypse drug" that eats away at flesh in its late-stages and has apparently entered the U.S.

Gruesome, sad photos of the damage the drug can do have gone viral over the Internet, as users stare at the pictures in utter disbelief of how the substance can seemingly turn individuals into zombies. The drug, whose real name is desomorphine, is three times more addictive than heroin, Time wrote in 2011, and krokodil essentially eats the flesh. It can literally rot the skin off of someone’s bone.

There are various videos that have been posted on YouTube, which show people who struggled with the drug. Mostly all of them are in Russian, and there’s one clip that shows a man’s leg being sawed off below the knee because the drug apparently rotted it away. Another reveals a woman writhing in pain as doctors try to clean out her wounds and removed the rotted flesh.

The average life expectancy of someone who uses the drug is 2 to 3 years and after seeing the photos and videos of people who are suffering from the drug's horrific side effects, it baffles many as to why anyone would ever even try it. But, according to an article from The Independent in 2011, people usually turn to the drug because it’s cheaper than heroin.

Krokodil is injected in to the veins, like heroin can be, but its homemade mixers are what add to its deadly components. Substances like gasoline, paint thinner, iodine and hydrochloric acid are combined to make “crocodile.”

"You can feel how disgusting it is when you're doing it," a krokodil addict told The Independent in 2011. "You're dreaming of heroin, of something that feels clean and not like poison. But you can't afford it, so you keep doing the krokodil. Until you die."

Though krokodil’s side effects are frightening, Leslie Bloom, CEO of DrugFreeAZ.org, said people shouldn’t be scared, according to 10news.com. "We don’t want the public to be alarmed," she said.

"What we want them to be is aware that this is a trend. There are other drug trends, too, that we see from time to time, especially with the synthetic drugs. This is a good reminder and a teaching moment."

The drug has been recreationally used in Russia for nearly a decade, but it was actually patented in the U.S. in 1934, MotherJones.com wrote, citing Espacenet.com.

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