Unlike NSAIDS, Tylenol is completely safe on the stomach and won’t cause gastritis or ulcer disease.
You see, acetaminophen is not an anti-inflammatory, which can be a downside, but that means it does not inhibit prostaglandin and prostacyclin the way NSAIDS do. NSAIDS cause inhibition of the cyclooxygenase (COX) enzyme which blocks prostaglandin and prostacyclin formation. The result is irritation and mucosal injury to the lining of the esophagus and stomach.
What is important here is that acetaminophen doesn’t work as an anti-inflammatory (so it isn’t as good for pain from inflammation) but because of that, it does not have the potential to cause bleeding in the gut that the NSAIDS do.