Archie Battersbee's mum said it took 15 minutes for her 12-year-old son to die after his life support was withdrawn.
Hollie Dance, 46, told The Mirror that the image of her boy "suffocating" will never leave her.
Archie died on August 6 after his parents lost their legal battle to keep him on life support.
The youngster's mum said there was nothing "dignified" about her son's death, describing it as "heartbreaking".
She said: “The morning Archie died, I told him how much I loved him.
“At midday they took his pipe out. It took 15 minutes for his heart to stop. There was nothing ‘dignified’ about his death.
"It was heartbreaking, watching your child suffocate. That image will never, ever leave me.”
Hollie has accused social media giants of failing to tackle deadly online challenges like the one that killed her son.
She believes there have been at least 82 deaths linked to the “blackout challenge”, in which people choke themselves until they pass out, with many more left brain damaged since it first began 14 years ago.
Archie spent more than four months in a coma after he was found with a ligature around his neck.
Hollie told The Mirror: “The social media companies don’t do enough to stop harmful content online.
“It’s out there and people are grooming our children to do these challenges, it’s disgusting. The people – they’re often adults, not children – who are demonstrating these challenges are sick.”
She found footage online of a man in his 30s tying something around his neck and pulling it tight.
She said: “This is a grown man demonstrating this ‘trick’ to children. Those people need to be held accountable. The police and the Government need to work together to stop this.”
Several reports of lethal or dangerous online challenges have emerged since Archie’s case.
Tori Barber told how her 10-year-old daughter was left with burns after spraying an aerosol deodorant with the nozzle right up against her skin to create a freezing sensation.
Jane Platt’s daughter Sarah, 15, was rushed to hospital in February 2020 after doing the “skullbreaker challenge”, which involves two people kicking the legs from under a third, making them fall over.
In the US, a wrongful death lawsuit was filed against TikTok last month blaming it for the deaths of two girls, aged eight and nine, who took part in the blackout challenge.
Last night there were calls for the UK Government to do more to stop further tragedies. Lib Dem digital spokesman Jamie Stone criticised delays to the Online Safety Bill.
Mr Stone said: “It’s more than four years since Conservative ministers promised new laws to tackle online harms, but we’re still waiting. We need clear, tough laws.”
But a Department for Digital, Culture, Media and Sport spokeswoman said: “The Online Safety BIll will force tech firms to protect children from dangerous viral stunts. Failing firms will face huge fines or have their sites blocked.”
Hollie is determined no-one should suffer like her son and his family.
She said: “That’s the legacy I want for Archie. I want to protect kids and the loved ones left behind. It’s unbearable.”
She found Archie unconscious at their home in Southend, Essex, on April 7, and gave CPR before he was taken to hospital.
He was transferred to the Royal London Hospital, where medics declared Archie “brain-stem dead”.
The Barts Health NHS Trust went to court, saying it was not in Archie’s “best interests” to continue treatment.
For weeks, Hollie and Archie’s dad, Paul Battersbee, 56, appealed through the courts. But their battle was in vain and life support was withdrawn on August 6.
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Archie’s family will now campaign to change laws covering life support.
Hollie wrote to Health Secretary Steve Barclay saying: “Depriving disabled children of their right to life because of their disability is unacceptable.”
Andrea Williams, of the Christian Legal Centre, which supported Hollie’s case, said: “We need a better system.”
Despite the tragic outcome, Hollie does not regret fighting in the courts.
She said: “I wouldn’t have changed a thing. That legal challenge bought us five extra months with my child.”
