How does aspirin work?

Dr. Matthew:

How does aspirin work? How does an aspirin know that it's my finger that hurts and not my elbow or my ear? How does it get to the place it needs to go?

-- No Doc, San Diego

Aspirin's pretty tricky. It's sure got you going. Bulletin: Aspirin knows nothin'. Couldn't tell your gall bladder from your third metatarsal. Science guys are still following aspirin around, trying to figure out exactly how it works. But at least they understand the basics. It so happens that the aspirin molecule is just the right size to fit into holes in at least two types of enzyme molecules; that plugs them up and slows or stops the production of hormone-like things called prostaglandins. It's prostaglandins that produce the pain, fever, and inflammation. So aspirin just kick-starts a chemical process in the body in general. If you stub your toe, then bash your skull on a kitchen cabinet, aspirin should take care of both boo-boos simultaneously.