Hydroxyzine
"I have a very high tolerance for meds (all meds) always have, even as a child.  Woke up in the middle of surgery at 7, after give twice the adult dosage bc I couldn't go to sleep.  I noticed on opiates they help but minimally.  I noticed for a brief period when I had benzo's for my anxiety, it aided my pain meds.  But they took me off for another kind and my opiates for pain and anxiety relief weren't being helped at all.  They just switched me and I notice the same aid to my medication the benzo's provided minus the fog.  It doesn't help with my severe chronic pain on its own (I wish it were that easy) but I find that my meds works so much better in conjunction.  My gabipentin seems to work better too. :) finally I can live a little better"