A Calgary father whose son has permanent brain damage from taking a street drug wants young people to hear about the tragedy.

Reg Hampton, a journalist at CTV who previously worked as a news anchor in Vancouver, posted his family's story on Facebook this week.

Last month his 18-year-old son Anthony took a pill he thought was OxyContin, but which was probably fentanyl, or a combination of the two, police told Hampton.

Anthony was found in his bed not breathing and turning blue. He has been in hospital for more than three weeks.

Hampton says his son, who was set to start culinary school at SAIT, now faces a long, uncertain journey of rehabilitation.

Reg Hampton speaks with his son Anthony last week as he began to recover in hospital. (Reg Hampton/Facebook )

An MRI report showed extensive and permanent brain damage, he says.

"But it might not be as grim as it sounds. What we've learned is despite all of the advances in medicine there is no way to determine how much of Anthony will come back," he said in his Facebook post

Anthony is now moving his hands and feet and his eyes are bright and moving around, Hampton says.

"The latest thing is that he cries. Or his face twists up like he's going to cry and then he coughs as if sobbing. As heart-breaking as it is to witness, it has to be a good sign," he said on Facebook.

Hampton says he was at first hesitant to go public with his son's plight.

"He's an adult, at least he has been for a month and a half, and can speak for himself. Except he can't," Hampton said on Facebook.

"But he is such a warm-hearted compassionate kid that I have to believe he would want to warn others not to do what he did"

Hampton said he wants the incident to get conversations going, to raise awareness about the dangers of street drugs so that other young people might not make the same mistake.