What Are The Side Affects Of Zantac?

my brother had a ct scan and a mri as well and they descovered white spots on either side of his brain along with one deep down in the center and they don't know what caused it. they have him on steriods and zantac right not while they keep running test which are coming back negitave every time. the symptoms are dizzyness, loss of appitite, loss of sleep, balance, ability to read and talk straight what could this possibly be????