Decompression sickness is the formation of nitrogen bubbles in body tissue and circulating blood that results from sudden decompression when a submerged person is elevated too quickly to the surface. It is seen most often in deep-sea divers and tunnel laborers.

Level 1 decompression sickness presents with joint pain, typically in the shoulders and elbows, with onset usually within an hour of surfacing and intensifying over the next 2 days. Other signs include pruritus, localized erythema, cyanosis, painful lymphadenopathy, and edema.

Level 2 decompression sickness is serious and may be life-threatening. Movement of bubbles can create severe risk of pulmonary embolism, neurologic damage, venous obstruction, increased heart pressure, and death. Symptoms include weakness, paresthesias, headache, ataxia, visual disturbance, memory loss, personality changes, dyspnea, wheezing, chest pain, and throat irritation.