Sum 41 frontman Deryck Whibley has left hospital after being treated for pneumonia.

The rock star was admitted to a medical facility earlier this week after being rushed to the ER.

Deryck’s wife Ariana Whibley revealed he has now returned home after his health showed signs of improvement.

“I’m very happy to be giving this update. Deryck was discharged after responding so well to his treatments,” Ariana wrote on her Instagram account on Saturday. “He is now under the care of his mother, who is a registered nurse and myself.”

“The pressure and strain on his heart and lungs has improved and he is able to breathe without as much pain,” she added.

Ariana went on to thank the “outpouring of love” and support Deryck had received since news broke of his hospitalisation. She said the reaction from fans had been “overwhelming” and had helped them stay positive following the health scare.

The Fat Lip singer's hospitalisation was revealed on Friday, when Ariana announced he was receiving treatment on the day the couple had planned to celebrate their eighth wedding anniversary.

“The scariest part is that there is a lot of strain on his heart and they are telling us that there is a possibility of heart failure,” Ariana said in a social media post.

Deryck was previously hospitalised after collapsing at his home in 2014. The 43-year-old star was in a coma for three days and later diagnosed with liver and kidney failure caused by alcohol abuse.