I unfortunately get very consistent knee pain when I backpack, particularly on rough trails, big granite steps up or down, and likewise often feel it when I sleep afterwards. It's very disturbing and I have a suspicion there is a genetic component of sensitivity to pain involved, as my dad was a major pain sufferer and always medicating for it.
Anyhow, I certainly don't want to let it stop my backpacking or talus hopping! I have a prescription for meloxicam, which is a once a day NSAID, ie like naprosyn and ibuprofen. It helps and feels easier on my stomach than other NSAIDs, but I still end up taking tylenol, too, sometimes. My doctor does have me take annual kidney and liver function tests to make sure it isn't harming me.
Maybe a more useful thread for me would be one on preventive exercises for knee pain!