The man, Tyler Smith, 19, died following the 100ft fall off the Stockport Viaduct in 2014.
Now, his mother, Deborah Cooper, 47, says he was let down by mental health services.
Mrs Cooper, said her son had made multiple threats to police and mental health staff hours earlier - telling them he was going to jump - and had tried to kill himself four times in 48 hours.
Tyler was in Stepping Hill hospital under the care of Pennine Care staff six hours before the fall after being admitted following a prescription drug overdose.
He had earlier tried to strangle himself in a police cell when he was detained for stealing paracetamol after escaping from hospital. After returning to Stepping Hill, medics discharged him.
Mrs Cooper warned medics they had made a 'huge mistake' and pleaded with them not to discharge her son. However medics discharged Tyler with a prescription for three-days worth of medication - despite numerous suicide attempts in the previous two days and threats he would jump from the bridge.
'The psychiatric nurse could see he wasn't well and that he needed to be admitted,' she added. 'She said he was high risk. Tyler admitted to her he was going to go and jump off the viaduct as soon as he got out. I told them Tyler was going to take all the medication he had been prescribed.
'Discharging him with three-days worth of drugs was the worst thing they could do. They knew it heightened his paranoia.'
He took a number of pills and fell from the bridge hours later on October 9, 2014. Tyler died of his injuries a week later at Wythenshawe hospital.
His death was ruled accidental after a coroner was told by a police officer he slipped from the bridge.
Mrs Cooper accused police of failing to tell mental health staff Tyler had tried to kill himself when he was detained - and slammed officers for arresting him in the first place. She said he should have been sectioned under the Mental Health Act as he was considered 'high risk'.