Does anyone else notice Acetaminophen (Tylenol) just seems to do nothing for them? I'm still taking the prescription NSAID Arthrotec for swelling/stiffness, and didn't really need the Oxycodone (Percoset) any longer during the day (plus I wanted to be able to drive short distances if needed). I decided a small amount of discomfort is par for the course anyway to be off the hard stuff. However, the deep ache in my knee just builds & builds through the day. It's at a very uncomfortable level by 7 PM. It's not even pain exactly, but completely distracting and uncomfortable. I tried 1000 mgs of Acetaminophen 3-4 times throughout this past week, but it was like eating candy. I didn't notice any improvement. Does one need to take it every 6 hrs for a couple of days to get any benefit?