which allergy medicine works best for itching skin

My father has very itchy skin and breaks out horribly.  The dermatologist put him on numerous medications, none which seemed to work real well.  He is currently on claritin and I would like to put him on another one also, because 2 seem to be better than 1.  We have tried zyrtec, allegra and other pills that are for bi-polar but help with itching.  I want him off the bi-polar meds.  He is allergic to Singular.  We gave spent a lot of time and money at the dermatalogist and I want this to stop going there, mostly because they put him on steriods, which negatively affected his health.  I  want to use a medicine that is a companion to the claritin.  He is also taking plavix and cilostazol.  Any info would be helpful.  Thank you.