Atarax worked very well for Casey and you can start at a really low dose and titrate up (it's prescription). Also, dermasmooth oil (also prescription) helps but is short term - check with your derm.
This is of course, in addition to above suggestions. But Atarax was a life saver! We didn't find Benadryl helped a lot
Mom to Casey born Feb 17/08(?LI/CIE), Sara born Feb 18/06, and Kaitlyn born July 2/03
Casey has been tested positive for a genetic mutation in the ICHTHYIN gene (which is indicative of either LI or CIE)