Sammie Bowman, 22, was helping her mum with last minute arrangements outside a rented cottage where the bridal party had gathered when she fell over backwards onto concrete.
The wedding party had gathered at Eastfield Farm Cottages at Thornton in the Yorkshire Wolds on May 31 to get ready for the wedding of her brother Andrew.
They had had their hair and make-up done and taken photos, when mum Debra Bowman, went out to her car with her daughter to sort out some clothes and buttonholes.
In a statement read to the court Mrs Bowman said: "She began to act very strangely, she rolled her fingers round her eyes like she was trying to swat a fly.
"She fell straight backwards onto her back.
"She made no attempt to save her fall and I heard a very loud bang as she hit her head on the ground."
Miss Bowman who had attended South Hunsley sixth form, and previously Market Weighton School, was rushed to York in a critical condition where a brain scan revealed a large blood clot immediately beneath the bone of the skull.
Although the prognosis was poor, doctors decided to operate in an attempt to save her life at Hull Royal Infirmary.
The operation was carried out, and a blood clot removed, but her injuries were "incompatible with life" and she died on June 2.
The inquest heard that Miss Bowman's collapse may have been caused by alcohol withdrawal, and her life had been blighted by an eating disorder, from the age of 12, which involved binge-eating and purging.
At one stage her weight plummeted to under seven stone.
She loved dogs and she had gained qualifications in the hope of achieving her ambition to join the police dogs section.
That morning she had eaten four breakfasts, and then been to the toilet three or four times to purge, her mother said.
In the months leading up to her death she had started drinking heavily.
Dr Laszlo Karsai, who carried out the post mortem examination, said it was more likely her seizure was triggered by alcohol withdrawal, which some people experiences as a headache, while others had "very unpleasant" fevers, sweats and tremors.
He added: "I have no doubt that the cause of death was multiple traumatic brain injuries."
The inquest heard that Miss Bowman, from Holme-on- Spalding Moor, had been admitted several times for in-patient treatment for eating disorders at units in York and Sheffield.
She regularly saw her GP and was in the care of a mental health team. Her clinical psychologist Dr Jemma Jackson saw her 75 times in 26 months.
At one session in October 2017, Sammie told her she was consuming 10 shots of gin per night.
At another, in March 2018, Miss Bowman told her she was experiencing alcohol withdrawal symptoms and was consuming a litre of rum per day.
"I urged Sammie to access support from specialist alcohol services and strongly advised her to have medical tests at her GP," she said in a statement.
Assistant Coroner Lorraine Harris gave a narrative verdict, concluding that a medical episode caused a fall where Sammie "struck her head causing a severe brain injury incompatible with life." She expressed her condolences to the family, saying how sad it was to lose "someone so young in such dreadful circumstances."
Outside the court her dad Alistair Bowman paid tribute to her daughter.
He said: "She was always laughing and bubbly and loved life. She loved her dogs. She was a joker. She was beautiful, a real nice young lady."