PART 2: The Mystery of How Tylenol Actually Works for Pain Here's where it gets fascinating - despite decades of use, we're still piecing together exactly HOW Tylenol relieves pain. THE COX ENZYME THEORY: Scientists thought Tylenol worked like ibuprofen by blocking COX-1 and COX-2 enzymes that produce pain-causing substances called prostaglandins. But here's the problem: Tylenol is a weak inhibitor of these enzymes, especially at the peripheral tissue level (the actual injury site). PERIPHERAL v