She was sent home until her condition deteriorated so badly that she was unable to communicate, an inquest heard.
Izzy had been studying for her AS exams when she began complaining of a bad headache, vomiting and fainting.
But after being seen at the Bristol Royal Infirmary she was sent home in the early hours of the morning - only to be readmitted 24 hours later when she got worse.
The teenager died in the intensive care unit on May 20, 2016, after an MRI scan showed irrecoverable brain swelling had caused brain stem death.
Her mother, Claire Booty, told the inquest the family had raised concerns about meningitis with a call operator, paramedics and doctors.
She said: "Given the symptoms were flu-like, I was given no guidance about what to look out for if her condition deteriorated. Izzy wasn't given a chance."
Izzy fell ill while studying for her exams, the inquest in Flax Bourton, Bristol, was told.
Her mother told the inquest: "When I got home about 6pm she was complaining of a headache and took paracetamol about 7pm.
"Her symptoms became worse, and during the evening my husband rang and we discussed it.
"I rang 111 to seek further advice. In particular my husband and I discussed meningitis and the letter."
She looked for a rash on the teenage girl's body, but told the inquest that the two male paramedics who attended were reluctant to examine her.
Paramedics Gary White and Christian Chambers, of South West Ambulance Service, took the teenager to hospital in an ambulance.
Mrs Booty said that the pair appeared "understandably reluctant" to examine Izzy as she was a teenage girl.
Mrs Booty said: "They seemed fixated about an upset stomach, but this wasn't one of the symptoms she was complaining of and this wasn't one of the symptoms we had raised when we called 111."
After being admitted at 1am, Isabel was seen by a doctor who sent her home after five hours - although she could hardly walk to her mother's car.
Mrs Booty told the inquest: "I was concerned that the examination was not particularly thorough and that the doctor was distracted.
"The school letter we had seemed to make no difference to the risk assessment which was undertaken."
Nurses reassured the pair that "it was just a virus" and she would recover in a couple of days, the inquest was told.
Isabel struggled to walk to the car and said: "I can't believe they're sending me home Mum, I feel so ill."
The following day Mrs Booty phoned her GP surgery at 5.10pm but was told it was too late for a home visit that day.
Due to Izzy's worsening condition Mrs Booty called for an ambulance at 5.30pm.
Ambulance staff arrived, by which time the teenager was unable to communicate and her limbs were "thrashing and flailing".
Within half an hour of arriving at A&E, Mrs Booty was told it was likely her daughter had meningitis, and she was taken to the intensive care unit.
But the following day her condition worsened and an MRI scan showed irreparable brain swelling had occurred and brain stem death had taken place.
Her death was recorded at 7.30pm on May 20, two days after Isabel had posted on Twitter: "Lol I knew something was up. Did not expect I'd be rushed to hospital in an ambulance, how peak."
Paramedic Pippa Bishop told the inquest she had been unable to pre-alert the hospital as she had to restrain Isabel on the stretcher.
Senior coroner for Avon, Maria Voisin, said: "Would it have been preferable to pre-alert before leaving the scene?"
Ms Bishop said: "With hindsight it would have been."
The inquest heard that the cause of death was "most likely meningococcal meningitis".
University Hospitals NHS Foundation Trust said in a rapid review after Izzy's death that the assessment and treatment were "appropriate" as initial symptoms were "not typical of meningitis".
Izzy's mother told the inquest she had told paramedics, nurses and the doctor that a fellow pupil alt St Brendan's Sixth Form College had recently been diagnosed with meningitis and that the school had issued a warning letter to parents.
Tributes quickly flooded in for the popular teenager with dozens describing her as a "gorgeous" and "bubbly" young woman who had an "amazing energy".
The inquest into her death is scheduled to last for five days and presided over by senior coroner, Maria Voisin.
This story was originally published by the Daily Telegraph
