Radiation can cause radiation sickness or poisoning if a person is exposed to excessive amounts over a short or long period of time. Acute radiation syndrome results from a high dose in a short time and symptoms include nausea, vomiting, diarrhea, fever, and in severe cases organ damage and death. Chronic radiation syndrome occurs from prolonged exposure and can increase cancer risks long-term as well as genetic mutations. The severity of symptoms depends on the level of exposure and includes headaches, fatigue, hair loss, and poor wound healing at moderate levels or organ failure at very high exposures. Minimizing exposure time and distance from sources can help prevent radiation sickness.