Rebecca Leighton, the nurse wrongly accused of contaminating saline solution, has been sacked by her employers at Stepping Hill Hospital.
The 27-year-old was dismissed following a hearing held on Friday after admitting she stole drugs from the Stockport hospital.
Leighton spent six weeks in custody earlier this year when police charged her with tampering with the solution but was cleared on 2 September.
However she was not allowed to return to work as she had already been suspended by the Nursing and Midwifery Council. Despite the suspension being lifted, Leighton was told she could only be reinstated at the hospital if the foundation trust agreed.
It emerged on Friday the hospital has now dismissed the nurse over her admission she stole tramadol, an opiate-based painkiller, from the ward.
A source close to Leighton said she was "very upset".
"She just wanted to return to work. The drugs she took were for her own use as she was ill at the time," a local paper reported.
Police are continuing to investigate the deaths of Tracey Arden, Arnold Lancaster and Derek Weaver, who died after being given the contaminated saline.