Holly Strawbridge, 34, gave powerful painkillers to Tyler Peck, 15, and one of his friends at her home in Salcombe, Devon.
She sat with both boys in the kitchen, drinking alcohol, inhaling aerosol fumes and taking a “cocktail” of her medication, police said.
Plymouth Crown Court heard that Strawbridge put drugs into their drinks, with Tyler’s friend later telling officers they “were drinking morphine” and Tyler was “swigging from the bottle”.
Tyler went to sleep at about 2.30am on February 2 last year but never woke up, having consumed fatal levels of the liquid morphine Oramorph and the drug Gabepentin that had been prescribed to his mother.
Strawbridge was convicted of two charges of child cruelty and two of supplying the boys with a Class A drug following a trial at Plymouth Crown Court in December.
Judge Paul Darlow jailed her for 10 years on Friday, telling her she had shown a “deliberate disregard” for her son’s welfare.
“That ill-treatment consisted of the supply and indeed encouragement of you for them to take your prescription drugs,” he said.
“That took place during the course of an evening of drinking at your house, an evening during the course of which you yourself were heavily under the influence of certainly alcohol and who knows whether drugs as well.
“The risk of serious injury to both those young boys was obvious. The consequences to Tyler, of course, were fatal.”
A post-mortem examination found the levels of Oramorph and Gabepentin in Tyler’s system were such that either drug could have individually caused his death.
The judge said what happened to Tyler had to be seen against a background of Strawbridge condoning drug-taking in her home.
“It can’t be said that the events of that night were a one-off, tragic incident where nothing of the sort had ever happened before,” he told Strawbridge.
The mother-of-five had a “misguided pride” in her house being a place where teenagers could come and “get hammered”, Judge Darlow said.
The court heard that Tyler was headstrong and sometimes physically intimidating, with Strawbridge allowing him to consume drugs and alcohol to deal with this.
Prosecuting, Peter Coombe said there was evidence that Strawbridge had been supplying Tyler with drugs and alcohol “for some years” before his death.
Representing Strawbridge, Piers Norsworthy described his client as a “loving mother” and said she had been assessed as having a low IQ.
Speaking after the sentence was passed, Tyler’s father, Ryan Peck, and stepmother, Sam Kibbler, said justice had “finally been served”.
“Tyler was funny, affectionate and caring. He was one of the lads, protective, loving and unique, and we miss him dearly,” they said.
“We want to take this opportunity to say thank you for all of the support we have had over the last 10 months since Tyler passed away and thank everyone involved in this case. You have all done Tyler proud.
“Unfortunately this trial was never going to bring our Tyler back, but we are glad that justice has finally been served and we can now try to find a way to move forward.”
Detective Inspector Ian Ringrose, of Devon and Cornwall Police, described the death of the teenager as “completely avoidable”.
“He died due to the actions of his mother who should have protected him, not put him in harm’s way,” he said.
“Strawbridge also put Tyler’s friend in grave danger that night and he is fortunate not to have suffered the same fate.”