Acute radiation syndrome (ARS), also known as radiation sickness, is a serious condition caused by the absorption of a high dose of ionizing radiation in a short period of time. ARS primarily affects rapidly dividing cells in the body, leading to damage in the bone marrow, gastrointestinal tract, and central nervous system. The syndrome progresses through four stages: prodromal, latent, manifest illness, and either recovery or death. In the prodromal stage, symptoms such as nausea, vomiting, and fatigue appear within a few hours after exposure. This is followed by the latent stage, during which symptoms may temporarily subside. In the manifest illness stage, the severity of symptoms varies depending on the received radiation dose. The three main forms of the syndrome in this stage are hematopoietic, gastrointestinal, and neurovascular, each affecting different body systems and causing symptoms such as infections, bleeding, diarrhea, and neurological deficits. Diagnosing ARS involves assessing the radiation exposure dose, clinical presentation of symptoms, and laboratory tests to evaluate blood cell counts. Treatment focuses on alleviating symptoms and preventing infections, which includes blood transfusions, antibiotics, and bone marrow stimulants. In severe cases, stem cell transplantation may be necessary. Understanding ARS is crucial for managing radiological and nuclear emergencies and improving the medical response at both individual and community levels. Timely diagnosis and appropriate treatment can significantly improve patient outcomes and survival rates.