"i used voltaren gel on some sore joints (and a tennis elbow). it worked as well as anything i have ever tried. i sometimes get killer tension headaches that first build up in the back of the neck.  when i felt one coming on, i used the gel on the back of the neck and shoulders.  the headache never developed.  before this experiment i would take 3 or 4 ibuprofen for one of these headaches and hope for the best.  the gel is now my standard treatment for these headaches."