The same pathways that help with physical pain seem to moderate existential distress.
The active drug in Tylenol, acetaminophen, is one of the best medications we have for helping people in pain. It's also one the most commonly overdosed substances in the world and puts about 60,000 Americans in the hospital every year. Several hundred people in the U.S. will die in 2013 from liver failure after acetaminophen overdose.
Tylenol isn't addictive like narcotics, and the kids don't take it to get high, which lends it an air of benignity and social acceptance not otherwise afforded to many pain medications. When people overdose on pills like Vicodin or Percocet, though, which contain acetaminophen, it's that component that often does the most damage.
Acetaminophen is also more accepted in that we don't think of Tylenol as altering our mental state. People can take it and still drive a car and go to work and remain fully present beings. But the more it's studied, the more it seems we may be overlooking subtle cognitive effects. In 2009, research showed that it seemed to dull the pain of social rejection -- sort of like alcohol or Xanax. The author of that study, Nathan DeWall at the University of Kentucky, said at that time, "Social pain, such as chronic loneliness, damages health as much as smoking and obesity."