In the prescription of non-narcotic analgesics the physician's main responsibility is to make sure that the quality-of-life improvement expected from the drug's use justifies the associated risk, low though it is, of fatal side effects. The range of acceptable risk depends, naturally, on the dosage and duration of the treatment and on those characteristics of the patient which bear on the drug's efficacy and safety. In the treatment of acute pain an additional, very important, factor is the patient's remaining life expectancy. Quantification of maximal acceptable risks is aided by formal decision-analytic considerations. Such analyses indicate that maximal acceptable risks vary by several orders of magnitude among various clinical situations and that they are more liberal than intuition might generally suggest.