The terms “dry drowning” and “secondary drowning” (also called submersion injuries) are often used interchangeably — even by some experts — but they’re actually different conditions, says Mark R. Zonfrillo, M.D., MSCE, attending physician in the Department of Emergency Medicine at the Children’s Hospital of Philadelphia.
In dry drowning, someone takes in a small amount of water through his or her nose and/or mouth, and it causes a spasm in the airway, causing it to close up.
In secondary drowning, the little bit of water gets into the lungs and causes inflammation or swelling that makes it difficult or impossible for the body to transfer oxygen to carbon dioxide and vice versa.
Dry drowning usually happens soon after exiting the water, but with secondary drowning, there can be a delay of up to 24 hours before the person shows signs of distress. Both can cause trouble breathing and, in worst-case scenarios, death.