Ans is None Answer was Pethidine according to Harrison 14/e, p 67, but it has changed in the 15th, 16th and 17th editions. See bel ow? Harrison 14/e --> "Narcotics or analgesics should be withheld until a definitive diagnosis or a definitive plan has been formulated, because these agents often make it more difficult to secure and to interpret the history and physical finding." Harrison 15/e, 16/e and 17/e --> "Narcotics or analgesics should not be withheld until a definitive diagnosis or a definitive plan has been formulated; obfuscation of the diagnosis by adequate analgesia is unlikely."