In countless movies and television shows, characters often employ the knockout power of chloroform to safely dispatch guards and bad guys who stand in their way. This is usually done by applying a small amount of the solution to a rag and shoving it in someone’s face. In a matter of minutes, the person is unconscious, and the hero moves on. Though this scene plays out often, real life is a bit different.

One of the biggest differences from movies to reality is how fast people react to chloroform. In the movies, people are knocked out almost immediately, but in real life it takes up to five minutes for someone to feel the chemical’s effects. This means that a character in a movie would have to roll around on the floor trying to keep a weird smelling rag on some bad guy’s face who is obviously fighting back and completely aware that someone is trying to smother him. Every time the rag is lifted and the bad guy gets a few doses of clean air, the process takes longer.

So, if chloroform isn’t nearly as crazy as it seems, where did this movie myth come from? Well, ever since its invention back in 1831, chloroform has been surrounded by stories of death, murder and general crime. For example, one America’s first serial killers, H. H. Holmes, reportedly used chloroform and other chemicals to kill up to 200 people in Chicago in 1893. Even more recently, in 2010, a lab technician in London used chloroform to knock out a 17-year-old girl.

Though the chemical has obtained an association with crime, it wasn’t always that way. In 1847, physicians started used chloroform as an anesthetic for medical procedures. The colorless, sweet-smelling liquid was applied to a sponge and placed over the patient’s mouth. However, finding the proper dosage proved difficult for physicians, and many patients were seriously injured or killed. According to the U.S. National Library of Medicine, “Acute chloroform toxicity results in impaired liver function, cardiac arrhythmia, nausea and central nervous system dysfunction.” The Environmental Protection Agency (EPA) also lists the chemical as a known carcinogen. For these reasons, chloroform fell out of favor in the medical community and is now used as a solvent in industrial plants and is used to create refrigerator freon.

In the end, chloroform does indeed knock people out. However, Hollywood makes it appear instant while it would take roughly five minutes or more in real life. The big flaw here isn’t necessarily the time it takes to render someone unconscious, but the ability for every single one of these action stars to do so without straight-up killing people with the chemical, a task that even doctor’s couldn’t figure out.