Critically ill patients require more than medical attention to their ongoing distress, as the disease puts strain on the metabolic processes in the body. This preludes to malnourishment associated with critical illness, which in the past was a major cause of mortality in this group. To provide a general understanding of complications of parenteral nutrition in critically ill patients in the current medical literature. Electronic database PubMed was used in this review and data was collected from relevant journal articles, randomized controlled trials, and observational studies containing the term used in the mesh: “nutritional therapy"[Mesh] AND “intensive care unit"[Mesh] within the title or abstract. Nutritional therapy in critically ill patients demands regular assessment of the patient’s condition, underlying metabolic processes, and regular assessment. Clinical judgment is important in combination with following guidelines and follow-up through laboratory tests. Prevention is key to successful parenteral nutrition with minimal complications. If complications do occur, it is important to recognize the warning signs and act fastidiously.