system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What do painkillers like Advil and Ibuprofen do to your liver if you take too many of them and why?
gpt
This is a very difficult question to ELI5, but:

Ibuprofen (and Advil, which is just a brand of ibuprofen) doesn't do much to your liver, you're likely thinking of paracetamol/acetaminophen (Panadol/Tylenol), but I'll get to that in a moment 

Ibuprofen falls into a drug class called an NSAID, or Non Steroidal Anti Inflammatory Drug. They work by inhibiting one of the enzymes that helps produce pain chemicals, less pain chemicals means less pain. That's really oversimplified, but accurate enough to understand.

The problem is, those pain chemicals have other functions too, and one of those is regulating blood flow to your kidneys. Too much ibuprofen and blood flow to your kidneys starts decreasing which can lead to damage, hypoxia (low oxygen), kidney stones and even toxicity.  Again, simplifying a little.

This is especially important if you're taking other drugs that affect either the pain chemicals or other aspects of the kidneys, these drugs include Ace Inhibitors (Ramipril/Tritace, perindopril/Coversyl, etc) and diuretics (furosemide/lasix, etacrynic acid/edecrin, etc) among others. 

These drug combinations can make the kidney problems far more likely and more severe.

Now as for paracetamol/acetaminophen, this drug **can** cause major liver problems. The basic reason is this:

The drug gets broken down by your liver into two byproducts, one is safe, one is toxic. When your liver is working fine, you mostly make the safe one. The problem is, the more paracetamol you take, the more of the bad byproduct you make.

This is important because the bad byproduct is toxic to the liver, which makes the liver less effective at making the safe byproduct, which means even more of the bad stuff.

So the more bad byproduct you get, the more you make, the more you make, the more damage you do and the more you make... until with a high enough dose of paracetamol, you make enough bad byproduct to shut down your liver completely.