A teenager died after taking double-strength MDMA tablets at a music festival, an inquest has heard.
Georgia Jones, 18, suffered a cardiac arrest and a 50-minute fit after taking two tablets at Portsmouth's Mutiny Festival, the city's coroner was told.
A pathologist said the level of MDMA intoxication in her blood was found to be "extremely high".
Tommy Cowan, 20, also died after collapsing at the festival in May, shortly after Ms Jones was taken ill.
The weekend event at King George V Playing Fields was cut short after 15 people were admitted to hospital, some with drug-related symptoms.
Organisers previously said the Sunday programme had been cancelled "as a safety precaution".
Ms Jones' friend, Chloe Edwards, told the inquest that the she was "slurring her words ... and wasn't with it".
The teenager's mother Janine Milburn said her daughter had used drugs in the past but was "growing up" and had not taken anything in the previous six months when she had started a new job at a care home.
She rushed to the festival site in time to go in the ambulance with her daughter to hospital after being alerted she had been taken ill.
Det Con Sharon Lewry told the hearing Ms Jones was not aware that the pills she had taken were double-strength.
A white powder, identified as MDMA, was found in the teenager's bag, she said.
"Georgia took two tablets not knowing they were double strength. It's likely the strength of the drugs she had taken were too strong for her body to handle," Det Con Lewry said.
The pathologist, Dr Brett Lockyer, said Ms Jones' blood level of MDMA was measured at 3,865 nanograms per millilitre.
Hampshire Constabulary previously said four suspects were still under investigation in connection with the deaths - a 21-year-old woman and a 20-year-old man, both from Waterlooville, and a 21 year-old man and a 20-year-old man, both from Havant.
An inquest into Mr Cowan's death will follow the current hearing, which will resume on Tuesday.