Staff at a hospital in Sydney's inner west should pay greater attention to the concerns of parents after a 13-year-old boy died hours after being discharged, the NSW Deputy State Coroner has recommended.

Carey Alexander was taken to Concord Hospital by his mother on August 9, 2014, when flu-like symptoms he had experienced for a few days started to get steadily worse.

Carey Alexander, 13, died of borderline myocarditis after being discharged from hospital. Credit:Nine News

While he was being cared for in the emergency department, he was extremely lethargic, had an irregular heartbeat, lost consciousness for 30 seconds after fainting in a toilet, and was unable to walk without assistance.

Throughout the night, his mother told clinical staff she was worried about several things, including the fact her son's skin was blotchy.