US death row inmate Christa Pike has released her first public statement since her botched execution in September.

"There hasn't been a moment since that night when I haven't been in pain," she said in a statement.

"My body hurts. My arms hurt. My hands hurt. My throat hurts. I still struggle to speak. And the pain isn't just physical. There is pain in my mind and in my soul."

Pike, 50, was discharged from hospital at the end of last month after surviving two lethal injections of the drug pentobarbital, which left her in a critical condition.

She has since been sent back to the prison where she has spent the last 30 years for murdering Colleen Slemmer in 1995.

Pike is thought to be the only person to have survived an execution attempt by lethal injection.