Physiological changes associated with aging affect the absorption, distribution, metabolism, and excretion of drugs and thus therapeutic outcomes. These changes may be further amplified by interactions with nutrients. The purpose of this review was to summarize drug-nutrient interactions found in elderly patients. Mechanisms of the interactions can be categorized as ex vivo bio-inactivations, interactions in absorption and elimination phases, and physiological interactions. The goal of enteral nutrition (EN) is to maximize the therapeutic response of medication without adversely affecting EN tolerance. Therefore, to ensure safety, consistent monitoring is necessary for enteral feeding of patients receiving medication via an enteral tube. Elderly patients receiving parenteral nutrition (PN) are often treated concomitantly with medication via the parenteral route. The stability and compatibility of PN formulations infused with other additives, including medication, may be influenced. Limitation of the number of prescriptions to essential medications only during the minimum period along with periodic re-evaluations of the treatment are thus necessary to minimize undesirable drug-nutrient interactions in elderly patients.