Drug therapy in seniors needs to be adapted to the capacity of the aged organism. The dosages of a high number of drugs from several classes (e.g., antibiotics, low molecular weight heparins) have to be modified according to age or reduced renal function, which is a common feature in old age. Moreover, elderly patients due to their physiological alterations exhibit an increased response to drugs having an influence on renal function: diuretics, nonsteroidal anti-inflammatory drugs, inhibitors of the renin-angiotensin-aldosterone system, and contrast media. The choice of drugs should consider their age-specific tolerability, i.e., fall-risk increasing drugs and those with strong anticholinergic side effects should be avoided. Analgesics, sedatives, and narcotics have to be selected according to the age of the patient and dosages should be adapted. Multimorbidity is often treated with polypharmacy, whereby it is not unusual that this is the cause for acute hospital admission. The necessity of all drugs prescribed has to be scrutinized and the drug burden should be reduced as clinically required.