"i have chronic sacroiliac joint and coccyx pain that does not show up on mri or x-ray and i&#039;ve used this patch for a little over 1 month with no side effects whatsoever.  i do notice that it takes about 2 to 3 days to feel the &quot;full effect&quot; of the medication and i do notice the increase in pain if i skip a day.  maximum pain for me with the patch is about a 2 and that&#039;s great."