I think the thing that really drove me away from painkillers were their reported long-term effects. Reading around, the most frequentyly reported side effect of ibuprofen and other NSAIDs (nonsteroidal anti-inflammatory drugs) is gastrointestinal bleeding. There may be other effects, including kidney failure. You are apparently at greater risk of these if you take high doses of these drugs over a long period of time. (However, I'm not sure exactly what a "high" dose is - or a "long" period, for that matter.)
From what I can tell (and as I've said before, I'm not an expert!) medical science seems to be undecided about the long-term effects of ibuprofen and other NSAIDs. In writing this I've done a bit of research on the Internet but found it frustratingly inconclusive. On some sites I found a scary list of horror stories (bleeding, kidney failure as above), and yet my doctor has told me (when I asked about the long term effects of taking ibuprofen) that the scare stories were mostly media overreaction and hysteria - and that there are few proven long-term effects.
So who do I trust? And what do I do?
Personally, I've adopted what I regard is a common sense approach. Seeing as we didn't evolve to be dependent on pain killers, my personal preference is not to take them unless I really, really need to.
As always you should do your own research - it's your body and if you have concerns start with your doctor.