In disturbing scenes on the field, Kelly was seen coughing up blood and needed the assistance of two trainers to leave the field after players from Queensland originally stopped to stay with her.
The NSWRL have now cleared her of any serious damage.
"Harvey Norman NSW Sky Blues centre Isabelle Kelly has been cleared of serious throat damage following an incident in last night's (Thursday) State of Origin Game One at CommBank Stadium," the NSWRL wrote in a statement.
"Tests have shown Kelly does not have a fracture to her larynx or windpipe damage.
"She is breathing more freely but still has swelling to the throat so she will remain in Westmead Hospital as a precautionary measure."
Blues coach Kylie Hilder spoke about the incident in Thursday night's press conference.
"She's in hospital, she's not great and there are concerns around her throat," Hilder said after the game.
"It's a big concern for me when we've got a player on the ground in discomfort and not in a great way and she was struggling to breathe."
"We're not out there to hurt people," she told ABC Sport.
"I love Izzy, so obviously I felt terrible she went down."
New South Wales will hope to be back in the winning column when they take on Queensland in the second game in the Women's Origin on June 22 in Townsville.