Hi My Baby Has Started His Sixth Month Now And

Hi my baby has started his sixth month now and sometimes he does not sleeps and keeps on crying and very restless, Wen checked with my pediatrician she said atarax can be given once in a while, but still I get scared to give the drops often to him, how often can it be given? But Once I give him 0.8ml he has a sound sleep. Please let me know is it dangerous in giving the drops and hw often it can be given?