The authors analyze the most important aspects one should bear in mind regarding medication in elderly patients. The authors study the pharmaco-kinetic and pharmaco-dynamic changes which occur with aging and how these influence variations in therapeutic responses and their most frequent adverse reactions among the elderly. The authors conclude that it is necessary to draw up individualized therapeutic plans for these patients. The authors also analyze the general recommendations made for administering and prescribing medications for the elderly. Considering that the administration of medication and the evaluation of adverse reactions are some of the most important responsibilities nurses have, the authors recommend specific programs be drawn up to evaluate the efficiency-risk binomial and to keep a close watch on adverse reactions in these patients.