Popular painkillers like ibuprofen and acetaminophen reduce people's empathy, dull their emotions and change how people process information. Acetaminophen is an ingredient in over 600 different medications, including being the main constituent of Tylenol.
Apparently, the brain's physical reaction to these types of pain responds in the same way to over-the-counter painkillers as the physical reaction underlying headaches or sore joints and muscle