Introduction: One of the most important investigations of the emergency room is the routine electrolytes test, which, in many cases, will provide some overall picture of the patient’s status and symptoms. Electrolyte imbalance may be fatal, therefore, early detection and treatment are crucial. These ion imbalances are prevalent with nearly a fourth of hospitalized patients. Potassium imbalance is one of the most important issues, due to its complications and many causes that can be behind it such as: vomiting and drugs. Clinicians should familiarize themselves with such disorders, in order to prevent complications, and provide the best outcome possible in such cases. Objectives: In this article, we aimed to review and discuss the pathophysiology of potassium imbalance, and its clinical features and management in an emergency department setting. Methods: PubMed database was used for articles selection, papers on were obtained and reviewed. Conclusion: In most patients, presenting with hypo or hyperkalemia, the cause can be apparent from history. The role of an ER physician goes deeper with the usage of laboratory tests as a confirmation, along with close cardiovascular monitoring and treating other imbalances. The clinician shall never be afraid of being more aggressive in treating potassium imbalances, especially when severe, symptomatic, refractory, and/or cardiac complications were noted. This can include IV administration of potassium (if the patient is hypokalemic), and 24 hours ECG monitoring. However, some patients may still need hospitalization and a further multidisciplinary approach may be needed.