Common Medical Abbreviations : > Rx = Treatment > Hx = History > Dx = Diagnosis > q = Every > qd = Everyday > qod = Every other day > qh = Every hour > C = With > S = Without > SS = On e half > SOS = If needed > AC = Before meals > PC = After meals > BID = Twice a day > TID = Thrice a day > QID = Four times a day > OD = Once a day > BT = Bed time