Death row inmate Christa Pike is conscious and speaking nearly a week after Tennessee's failed execution, her lawyers say.
The convicted murderer was given two doses of pentobarbital, a lethal drug used by the US state in executions, last Wednesday.
Pike's lawyers said her recovery in hospital was "medically unprecedented".
They said in a statement: "Against all odds, Christa Pike is conscious, speaking, and continues to receive critical medical care. Despite the severe damage she endured to her arms, she is still handcuffed and shackled to the bed.
"Her recovery is medically unprecedented. Her prognosis remains unclear but, at a minimum, we expect a long recovery."
In a court filing last week, Pike's legal team said problems with the IV lines had caused the barbiturate pentobarbital to go into her body, instead of her bloodstream.
She was taken to a hospital in Nashville, Tennessee, where her lawyers previously said she was in a "critical condition" and on a ventilator.
Pike's lawyers are set to attend court on Wednesday as they seek to learn more about what happened in the failed execution.
Frank Strada, commissioner of Tennessee's Department of Correction, has announced he will step down this month while an independent review determines what happened, state governor Bill Lee said on Saturday.
Recovery could take months
Dr Joel Zivot, a professor of anaesthesiology and surgery who consulted as an expert for Pike's legal team, said the latest development "bodes well for a good recovery".
However, he said that it could take months to determine exactly what her recovery might look like, and whether her competency can be restored to a level that might enable the state to try again to execute her.
Authorities have not yet said whether they will try again to execute Pike.
"She has recovered to a certain degree that she's able to be off a ventilator and able to speak, but in no way would I announce her free of further serious risk," Dr Zivot said.
"There's still a lot of bad things that can happen here, even when everyone is doing their job well."
Pike, 50, was set to be the first woman to be executed in Tennessee for more than 200 years after being convicted of killing her 19-year-old classmate Colleen Slemmer in 1995.
She had been granted a reprieve around an hour before her initial execution was scheduled to take place, but the decision was later overturned by the US Supreme Court.
'Christa is a survivor'
Pike, who was 18 when the crime was committed, does not deny the killing, but her supporters have argued the state should consider her age at the time, mental illness and a history of severe sexual abuse, including rape, beginning when she was a child.
Following the killing, Pike was diagnosed with bipolar disorder and post-traumatic stress disorder, her lawyers said.
In their statement on Tuesday, her lawyers added that they are continuing to ask Mr Lee to have Pike's sentence changed to life in prison without the possibility of parole.
"Christa is a survivor and will take recovery one day at a time," her lawyers said.
Tadaryl Shipp, Pike's former boyfriend who was also convicted of killing Ms Slemmer, received a life sentence with the possibility of ​parole because of his age. He was 17 when the crime was committed.
