Compared to controls , i.v. infusion of paracetamol was associated with significantly lower VAS score 15 and 30 min after the start of medication ; also , there was a significantly lower incidence of need for rescue medication ( 8/57 [ 14 % ] vs 49/59 [ 83.1 % ] , P < 0.001 ) at 60 min after the start of medication .