Christa Pike, who survived an attempt to execute her by lethal injection in the US state of Tennessee, has regained consciousness and is speaking, her lawyers say.

Despite severe injuries to her arms, Pike is "still handcuffed and shackled to the bed," where she "continues to receive critical medical care," her team of public defence attorneys wrote on Tuesday.

The 50-year-old was sentenced to death for her role in the torture-murder of a schoolmate three decades ago.

She survived a botched execution attempt on the night of September 30 at Riverbend Maximum Security Institution in Nashville, the state capital, and has been hospitalised since then.

Two doses of the drug pentobarbital had been administered to her intravenously at the prison.

Hospital staff then worked to save Pike's life and clear the drug from her system, her attorneys said in an emergency motion, which seeks a court order for Tennessee's Department of Correction to preserve evidence.

The bungled attempt to establish intravenous lines left both her arms "swollen, burned and blistered," the apparent result of the pentobarbital, a highly alkaline and caustic substance, seeping into the tissues under her skin, the court filing said.

The episode capped a 30-year saga that began with the murder of a 19-year-old vocational student, Colleen Slemmer, by an emotionally troubled classmate whose punishment, her lawyers say, failed to account for her own childhood trauma as the victim of sexual abuse, neglect and untreated mental illness.

Pike went from being the first woman Tennessee had tried to put to death in more than 200 years to becoming the first person in the United States known to have survived after execution drugs were administered.

Pike was 18 in January 1995 when she, a 17-year-old boyfriend and a third companion lured Slemmer into a wooded area where they tortured and killed her.

Pike confessed to the killing and was convicted the following year of first-degree murder. 

Tennessee Governor Bill Lee has halted any further attempts to carry out the death penalty for the rest of 2026 and ordered an independent review of what went wrong.