Over the past few days she has experienced - is still experiencing - every kind of agony: vomiting, stomach cramps, chills, hallucinations, the 'shakes', insomnia... sleep, of course, is impossible when you are being weaned off heroin and are 'cold turkey'.
"It's been horrible to watch," says a relative. But, then, what you are about to read is a horror story.
It begins, or at least it came to light, at a Roman Catholic primary school in Glasgow last week. One moment a little girl was sitting at her desk, the next she was slumped over it and blue lights were flashing outside the playground.
Her body, it emerged, was riddled with heroin. She had been burning the drug and smoking it through tin foil. It's called 'chasing the dragon'. She had been 'chasing the dragon' since she was 10 years old.
She is now 11 - the youngest heroin addict on record in Britain. What a shameful statistic. We shall call this 'statistic' Jenny.
Jenny is being treated in the high dependency unit of Glasgow's Royal Hospital For Sick Children.
Her ward has pink and yellow wallpaper and a toy room. Apart from these surroundings, and her age, there is little to distinguish Jenny from any other emaciated, agitated, desperate junkie suffering from withdrawal symptoms.
We have all seen these wretched people on TV or on street corners. But never in a Roman Catholic primary school or a children's hospital.
"You have to stop and remind yourself that she is an 11-year-old girl," said someone who works at the hospital.
'Cold turkey' has made her aggressive and often difficult to deal with. On one occasion she is believed to have tried to leave hospital, only to be stopped by staff.
These are not a criticisms of the little girl, just the brutal reality of what 'smack' or 'skag' or whatever other word you care to call heroin can do to someone.
So we know what happened. But not why or how.
Jenny told doctors that she obtained the heroin after taking a bus to a dealer at a Glasgow shopping centre. This is the version of events that was reported in newspapers and on TV.
But there was no trip on a No 8 single-decker bus to the Pollok Centre on the city's south side. There was no dealer. Jenny got heroin from her mother. Her mother is a heroin addict.
Jenny used to watch her 'chase the dragon' in their council flat. She watched, and like any child she copied her mother; stealing from her mother's stash of heroin to begin with and then, it is claimed, when her mother found out, pleading with her just to give her a 'fix'.
Her mother, according to a close family member, gave in and became her own daughter's 'dealer'. She probably thought she was doing Jenny a favour.
It is easy to look for scapegoats, to assign blame in cases such as this. Nevertheless, it is difficult to avoid the conclusion that almost everyone who could - and should - have helped Jenny failed her.
Social services have been involved in Jenny's life for the past 2 years. Shortly before Christmas she (and her 7-year-old sister) were placed in foster care before going to live with relatives.
It was known that their mother was a heroin addict, yet Jenny, it is alleged, was still able to get heroin from her mother during unsupervised visits.
Jenny and her sister also have a baby brother. Where is he now? Still with his mother, it seems, but then Jenny's story is just the tip of an iceberg. Researchers working for the National Treatment Association for England have found 30 heroin users under the age of 13 in Newcastle and 60 in Glasgow, the city where Jenny was born.
Across Scotland, more than 20,000 children live with parents addicted to hard drugs.
One drug-abusing mother told a research team from Glasgow University how she injected in front of her son.
"He wouldn't leave the room, just stayed sitting, and so in the end I did it in front of him while he sat there, the tears rolling down his face," the woman admitted. "I just said: 'Sorry son, you know Mammy's sick. You should have gone out of the room. I had to do it.'"
This is how it must have been for Jenny, only worse. Her mother smoked heroin in front of her. Her father injected it.
Her mother had Jenny when she was 16; her sister was born 4 years later and their brother just before Christmas. They have the same father. But the family have never lived together.
What's it like living with a mother who is a heroin addict?
"She couldn't even get the girls out of bed in the morning for school," said someone who knows the family. "She was too busy staying up all night taking drugs to get up."
Social services laid on taxis to take Jenny and her sister to school, but they still frequently missed class.
There was also a dramatic change in Jenny's appearance.
"We knew something was wrong with her because she was getting thinner and thinner," said one relative. "We thought she might have had anorexia because she had been teased terribly at school for being overweight. She went from a chubby wee thing to totally skeletal."
She was not anorexic, of course. Weight loss is one of the more obvious symptoms of drug abuse.
There were other signs, too. Black foil marks began to materialise on her clothes.
HER extended family suspected something was wrong, but did not intervene. Scandalously, you might think, it was only in December, following the birth of her third child, that Jenny's mother admitted she could no longer 'cope' and the girls were placed in the care of foster parents before going to live with relatives.
We now know that Jenny had been taking heroin, missing school, losing weight and turning up with scorched clothes for the previous nine months.
Even now, it almost impossible to believe that no one did anything to help.
"Apparently, when her mother discovered Jenny smoking heroin, she was too far gone with her own problem to stop her," said a close relative.
"Even when she went into foster care, her mum got unsupervised visits. She just kept on demanding heroin and her mother just kept supplying her with it.
"She can't be put on a treatment programme with methadone because she is too young, so she has had to come off heroin completely and go 'cold turkey'. Her childhood has been snatched away from her. She never really had a chance."
Of course, the relative insists she found out about Jenny's appalling predicament only recently. No one, it seems, knew at the time. Not her, not Jenny's grandmother, not her great-grandmother, not social services. No one.
As her great-grandmother told the Mail: "She was such a good girl and had never been in any trouble before. I can't believe it has come to this."
Jenny's mother checked into a detox clinic in Glasgow's south side within days of her daughter being taken to hospital. She is understood to have visited her daughter only once.
The relative added: "She is just a coward - too scared to face up to what she has done. I blame her totally for what has happened to an innocent child. She was a lovable, caring and bright girl whose life has been ruined."