BrainStuff Classics: How Does Aspirin Work?

How does aspirin target your pain? The plants that aspirin were derived from have been used as medicine for about 6000 years, we finally discovered how it works in 1971, and we explain it in this episode of BrainStuff.

Learn more about your ad-choices at https://www.iheartpodcastnetwork.com

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from How Stuff Works. Hey brain Stuff,
I'm Lauren Vogelbaum, and today's episode is a brain Stuff classic,
How does Aspirin Work? I wrote this one for our
YouTube channel a while back while I was going through
a pain research phase, which yes, is just about as
goth as it sounds. It was performed for the podcast

(00:23):
by our former host, Christian Saga. Let's dive in, Hey
brain Stuff. It's Christian Sager here. There are lots of
ways to numb yourself to the minor aches and pains
that we humans accrew in our daily lives. But today
we're talking about aspirin. Why aspirin, Because although aspirin as

(00:46):
we know it has only existed since the late eighteen hundreds,
the plant that it was originally derived from, willow, is
probably the oldest known pain killer in history. Records of
people using willow leaves to relieve pain and fevers stretch
back six thousand years to ancient Assyria and sumer Willow

(01:07):
was also put to use in ancient Egypt, Babylon, and China,
and Hippocrates thought it was pretty rad especially for pain
during childbirth. In the seventeen and eighteen hundreds, scientists worked
on identifying, extracting, and purifying the active ingredient in willow,

(01:27):
which turned out to be a chemical they called salison,
which they further discovered your digestive system changes into salacilic acid,
which is what reacts with stuff in your body to
relieve pain, reduced fever, and swelling. More on how all
that works In a second, but first salacilic acid. It

(01:49):
was a pharmacological superstar. German chemists figured out how to
synthesize it on an industrial scale in the eighteen seventies,
effectively ending millennia of willow powder use. But it had
its drawbacks. Lots of patients couldn't stomach it literally, it
was really hard on the stomach lining The son of

(02:11):
one such patient, a chemist with Friedrich bear in Company
by the name of Felix Hoffman, thought it might be
less irritating if it was less acidic, so Hoffman converted
it to what bear in Company dubbed aspirin in eight
Aspirin has become the popular and less ridiculous to pronounce

(02:33):
name for Hoffman's chemical compound, a setal silic acid or salicylate.
It works as humanity finally figured out in the nineteen
seventies by preventing yourselves from using cyclo oxygen ase to
to create prostaglandins. And don't worry, I'm about to unpack

(02:54):
all of those words. Let's start with the idea that
lots of pain is useful evolutionarily speaking, when you feel
pain due to an injury like a burn or a
twisted ankle, it prompts you to take your hand away
from that hot thing real quick, or to keep your
weight off the ankle until it heals. It's it's useful, right.

(03:14):
Pain from an injury to anything but the nervous system
is called no susceptive pain. After specialized sensory neurons located
throughout your body called no susceptors, They alert your brain
to damage. With the help of the damaged tissue itself,
cells in the hurt areas start producing enzymes that work

(03:36):
together to create a few signal chemicals, including those prostaglandins
I mentioned a minute ago. Prostaglandins tell your no susceptors, no, hey, seriously,
there is a problem here. They make your no susceptors
increase the signal to your brain. You feel the pain
more acutely now Prostaglandins are also one of the chemicals

(03:58):
that cause inflammation in the tissue around a wound. They
make your blood vessels expand, flooding the damaged tissue with
all the immune systems stuff your body sends to protect
the wound from infection and to help it to heal.
All of this is great right up until it isn't.
After a certain point. You don't need continual acute pain

(04:21):
as a reminder that you're injured. We know, and some
non susceptive pain and swelling is warning us about stimuli
that we can't easily avoid, like headaches, arthritis, or period cramps.
In the case of arthritis, that inflammation can even cause
more damage in the long run. Here's where aspirin swoops
in to save the day. When you take aspirin, it's

(04:43):
absorbed by your digestive tract into your blood stream, which
takes it throughout your body, including places where cells are
excreting the enzymes necessary to produce prostaglandins. Molecules of aspirin
lock up with one of those enzymes, cyclo oxygenase too.
Once a molecule of cyclo oxygenase two is locked into

(05:06):
a molecule of aspirin, it can't help create prostaglandins, which
means fewer prostaglandins, which means that the pain signals to
your brain don't increase as much and the tissue in
the area doesn't swell as much. Hey, thanks thousands of
years of science. Today's episode was produced by Tyler Klang.

(05:30):
If you miss Christian and want to hear more from him,
check out his pop culture podcast super Context, And of course,
for more on this and lots of other anti inflammatory topics,
visit our home planet, how stuff works dot com.