After two teenage suppliers were jailed at Teesside Crown Court on Monday, her mother Kerry Roberts said: "We miss Leah every day, her death left a huge hole in our lives that can never be filled.
"No sentence can ever change that, but what we do wish for is for young people to realise the deadly consequences of taking drugs.
"That adults are not just saying they are dangerous to spoil your fun, but that you truly understand how dangerous they are.
"You have your whole life ahead of you, please don't risk losing it.
"If Leah's death has not made you think twice, what will?"
Judge Jonathan Carroll paid tribute to Ms Roberts who watched the proceedings, and he said the case was "truly tragic".
"She had everything to live for, the excitement rightfully held by young people in anticipation of their futures, a new sister on the way whom she never got to meet, all of that hope and aspiration for the future extinguished because of the evil that drugs represent in our society."
Judge Carroll said young people, thinking they were indestructible, wrongly thought drugs were fun.
"This case is here for anybody and everybody who might think that — drugs destroy lives."
The judge noted just two young people had the courage to tell the police what had happened the night Leah died, saying it was an example of the selfishness drugs caused.
Robert Mochrie, defending Southern, said the tragedy reminded him of the death of 18-year-old Leah Betts in the 1990s: "This is history repeating itself".
"When I was younger it was Leah Betts who was the unfortunate lady who died taking the exact same drug," he said.
Mr Mochrie said Ms Betts' case was used as a warning to young people then, adding: "Hopefully, if there is any good to come from this, it is that those in the local community will be acutely aware of what happened and will chose to lead their lives without the use of recreational drugs."
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