I have passed kidney stones time after time. I keep Vicodin 750's in the freezer just in case -- fortunately I have always managed to pass the stones but one got "stuck" for a week or so.

My Doctor found elevated levels of uric acid in my blood -- this is one cause of kidney stones. I take a drug called allopurinol to lower the uric acid levels and haven't passed any "gravel" or had any pain urinating for years now. (Knock on wood).