Name: Nobody Knows How Tylenol Works
Uploaded: 2026-03-20T21:49:04.000Z
Duration: 7 min 48 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Once upon a time, There was a YouTuber named me who hit his finger with a hammer.

Adverbs of degree

So he decided to take some Tylenol and asked himself the same question we've all how does this painkiller know where the pain is?

So we went online to tylenol.com to read about how it works and came across this.

It is thought to work to relieve minor aches and pains by elevating the body's overall pain threshold so you feel less pain.

Surely this drug, which as of 2016 was used regularly by 79% of the American population, isn't just a magic beam that nobody understands, right?

Nobody knows exactly how acetaminophen, AKA paracetamol, AKA the active ingredient in Tylenol, works.

We know that it's safe as long as you stick to the recommended dosage.

But for everything else, we can only guess.

I guess I have to say this now, there's no reason to think it works by giving your kids autism.

So how did this drug get created and sold without anyone knowing what it literally does?

And what, at this point are the leading theories as to what exactly it's doing to you?

Back in 1884, there was a fellow who had intestinal worms and was getting help from two physicians named Arnold Kahn and Paul Hepp.

Their mentor, Adolph Kussmal, thought it'd be helpful to give the patient naphthalene, a thing I myself only know from its work putting needles in space.

So I'm not sure what it does for intestinal worms, but hey, that's why I'm not a doctor.

The pharmacy sends Con and Hepp some naphthalene so they can deworm this guy.

But when they give it to him, nothing happens to the worms.

But mysteriously, his fever goes down, which nobody had ever observed as an effect of naphthphalene.

Suspicious that their NAF might have been caught with something, the boys went back to the pharmacy, like, hey, what was in this naphthalene?

And found out that actually the pharmacy hadn't sent them naphthalene at all.

They'd accidentally sent them something called acetenolide, a chemical that was better known for making dyes.

It was the kind of mix up that could only happen back when pharmacies didn't just sell medicines, they also sold chemicals to research labs.

So Hepp hit up his brother, who worked at a pharmaceutical company and told him to look into acetenolide as a fever drug, which the company did, eventually selling it under the name antifebrin.

At this point, still, nobody knew how acetenolide reduced fever, since they'd learned about that use accidentally.

It caused something called methemy globinemia, a beast of a word that I really hope my writer hasn't put in the script five more times to frustrate me.

As tough as it is to say methemoglobinemia, it's far worse to have methemoglobinemia.

It messes with your red blood cell's ability to carry oxygen throughout your body, which, along with being dangerous and even deadly, can also make your skin, nails or lips blue.

So suddenly, everyone wanted to make a methymeglomenemia free version of antifebrin.

One was sphenocidin, which was the most popular until 1947.

The other was acetaminophen, the subject of this video.

It didn't get its day in the sun until later, because when it was created, people still thought it might cause meth methemoglobinemia.

But, uh oh, not only did phenycitin have its own issues, namely being linked to kidney problems, but

it turns out when you take acetenolide or phenycitin, your body immediately converts it to acetaminophen anyway, so it was totally fine and wouldn't give you that thing.

And so in 1955, acetaminophen hit the market, packaged up as Tylenol.

And again, at this point, nobody making it or selling it knew how it handled your fever or killed your pain.

They just knew that it worked its magic without making your kidneys go crazy or turning you blue.

Which takes us essentially to the present day.

Acetaminophen is an active ingredient in over 600 medicines currently in use, and

its global annual market is estimated at $9.5 billion.

In fact, statistically speaking, I'm confident that several of the people watching the video are doing so on acetaminophen.

I guess for a long time, acetaminophen was believed to be an nsaid, like ibuprofen, the active ingredient in Advil and others.

understanding how NSAIDs work is still helpful in taking a stab at Tylenol to completely oversimplify when you hit your finger with a hammer, an electric signal we call pain travels from the spot you hit through what's called your peripheral nervous systemthe wiring in your fingy that can feel you hit it with a hammer to your central nervous systemyour spinal cord and brain.

At the same time, an enzyme called COX2 in your fingy cells starts cranking out something called prostaglandins, a word I am not interested in saying anymore.

Ouchies do a few things like causing inflammation and traveling to your brain, saying, hey, if you get any pain signals, you should really feel those right now.

And so, thanks to the ouchies, your finger is inflamed, your brain is more sensitive to pain, and

If you take ibuprofen, it basically trots around your body via your bloodstream, and

whenever it sees COX enzymes working, tells them to cut it out.

So in this, when ibuprofen arrives at your finger, it tells the Cox 2s to slow their roll so you have fewer ouchies and therefore less inflammation and less pain.

But those won't be the only COX enzymes that slow down others, like ones firming up your stomach lining.

Get told to take a break too, which is why ibuprofen sometimes gives you a tummy ache, especially if you haven't eaten.

The tummy ache factor is actually part of why we know Tylenol is not an nsaid.

Tylenol doesn't give you the tummy ache, which gives us reason to believe that whatever its true doing, it's not doing in the entire body the way ibuprofen is.

We also believe this because Tylenol doesn't help with inflammation, which suggests that it's not working on the Cox 2S at the site of pain.

Instead, it's believed that whatever Tylenol is doing is limited to your brain and central nervous system.

And potentially what it's doing there in the command center isn't actually that different from what the NSAIDs do at the scene of the crime.

One of the top theories as of now is that Tylenol is also telling COX to stop cooking up ouchies, but

And while, surprise, surprise, we don't actually know how its work gets limited to the central nervous nervous system, it does seem to only work in parts of the body with low peroxide, like the brain.

So it's possible that it travels everywhere, but

can only work in your noggin this explanation seems like a plausible one for how Tylenol reduces fever, but

there's a chance the painkilling mechanism is something else entirely, with one idea out there being that it toys around with some of the same neurotransmitters that make you feel high when you smoke weed.

Not that you and I or any of us would do something like that, but

no two things I read about that seem to agree on how or even if that worked.

Though I can tell you for free that whatever else it's doing, Tylenol does not get you high.

High there's another theory that maybe Tylenol's painkilling mechanism has something to do with serotonin, AKA the happy hormone, but

it's not clear exactly how, if at all, that works either.

So while it's certainly strange that we don't know how Tylenol worksafter all, most drugs are invented on purpose, is it necessarily a problem?

Acetaminophen is regarded as so safe and so effective that it's maybe not worth spending a ton of resources figuring out what exactly it does.

After all, it's not like knowing how it works would help us make a better version.

Instead, we should probably finally get around to treating that guy's intestinal worms.

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