Raleigh, N.C. — The death of a South Carolina boy is being blamed on a phenomenon called secondary drowning – lung damage that is caused by ingesting water but that is not fatal right away.

The 10-year-old swallowed water while swimming at a pool in Goose Creek, S.C., over the weekend.

He complained that he couldn't breathe and was tired after getting out of the pool. The boy drowned while taking a nap in his bed, authorities said.

His death, the result of secondary drowning, was caused by a biological change in the lungs after a near-drowning experience.

“There is a condition called acute respiratory distress syndrome (secondary drowning) where there can be inflammation of the lungs when you ingest a lot of water,” WRAL's Dr. Allen Mask said.

Mask said there are signs of secondary drowning for which you can watch: difficulty breathing, extreme fatigue and a change in behavior.

If someone inhales a significant amount of water or is pulled out of the water coughing, that person should probably go to the emergency room to be checked out, Mask said. If left untreated, secondary drowning syndrome could be fatal.

Raleigh father Tim Scranton said that after learning about secondary drowning he will keep a closer eye on his son after swimming.

“Leaving the pool, if I see him having those kind of symptoms, I would take it a lot more seriously than before,” Scranton said.

Secondary drowning can occur as late as 72 hours after someone initially ingests the water.