An inquest heard that a teenager who died after taking ecstasy on a night out at Fabric bought another pill inside the nightclub because he felt "frustrated" at not feeling the effects.
Ryan Browne, 18, died in hospital on June 25 this year after becoming ill in the now-closed night spot in Farringdon, northLondon.
Poplar Coroner's Court heard Mr Browne was among a group of seven friends, who had smuggled the drugs, also known as MDMA, into the club in their socks.
His friends realised he had become unwell and he was taken to the medical area inside the club, where he had two seizures and went into cardiac arrest.
A post mortem examination found he had fatal levels of MDMA in his blood, with the pathologist Naveena Singh saying: "The cause of death appears to be the MDMA. The blood level of MDMA is considerably higher than the upper limit associated with recreational use and is within the fatal range."
Ben Hole, a friend of the student, said Mr Browne had been among a smaller group of friends who had picked up the drugs from a dealer near Luton Sixth Form College.
The friends had decided to go to Fabric because he said: "Fabric was always known to us as the club to go to in London if you wanted to take ecstasy, because of the music and feedback from other people.
"It's always been known as that club because of the music that's played.
"I was under the impression you could buy drugs inside Fabric but we also said you never do that.
"We were naive and thought you only buy things off people you know."
Mr Hole said the group had taken some of the drugs in the toilet shortly after they entered the club and then went to the dance floor.
Mr Hole added that they had been searched on entry to the club but were not instructed to remove their shoes.
Around 15 minutes after taking the first of the drugs, Mr Hole said the effects were "quite overwhelming" and he was sick in the toilet.
He said: "I went back to the dance floor, still feeling the effects and asking everyone 'are you feeling it? Are you feeling it?'
"Ryan began to become quite frustrated so he decided to take another one."
Later Mr Browne was spotted talking to someone near the DJ booth, where an "exchange" took place, according to Mr Hole.
After taking more drugs, Mr Browne began to look unwell. Mr Hole said: "I kept seeing him during the night and he did not look good. With the state I was in and everyone else was in I did not think much of it."
Friends who sat with Mr Browne on a beanbag told Mr Hole they believed he began hallucinating and saying "Daniel Sturridge" and was "twitching".
Another friend, Ryan Locke, said he was told by a bouncer to take Mr Browne to the medical area as the pair tried to go outside to get some air.
A medic treating Mr Browne recorded his temperature as 41.6C, before paramedics were called shortly before 2am and he went into cardiac arrest.
Esther Finn, who had worked for Fabric as a medic for more than five years, said his lips were blue and he had been speaking in "incoherent mumbling".
Mr Browne, described as a "keen sportsman" who had mild asthma, was taken to the Royal London Hospital at 2.55am and died at 11.20am later that day.
A toxicology report found the level of MDMA in his blood was 2.48 microgrammes per millilitre, above the upper recreational limit of 0.35mg per ml.
The club's general manager Luke Laws told the coroner the club was near its 1,500 capacity that night and there were dozens of security staff working, along with three trained medics.
He warned about an "arms race" in illegal drugs manufacture linked to so-called legal highs and said the club needed to "do more" to improve the entry of drugs into the venue.
Senior coroner Mary Hassell concluded Mr Browne's death was drug-related.
She said: "All of the evidence points in the same direction, that Ryan's death was drug related. I'm completely satisfied it was not his intention to end his life.
"This was recreational drug use gone wrong.
"He had taken ecstasy four or five times in his life. He was a naive user - he was naive in life as well but he was a naive drug user.
"The drugs in his system were enough to kill somebody who was very habituated and he was very far from habituated."
She refused to call it an "overdose" because she said illegal drugs "don't come with a dose on the label".
Speaking directly to Mr Browne's family in court, including his mother Sarah, Ms Hassell added: "I don't know how to make sense of a completely healthy young man with his life ahead of him succumbing in this way."
In a statement to the coroner, Mrs Browne said her son, from St Albans, "always had a cheeky grin on his face and will be sorely missed".
Mr Browne's death was one of two that led to the eventual closure of the club in early September.
Islington Council revoked its licence after finding it had a "culture of drug use" which staff were "incapable of controlling".
Mr Laws defended the club in court, saying it had had a deal with a drug awareness charity, The Loop, before the nightclub was closed, and stressed the need for more education about safe dosages.
He warned against people "popping pills like Smarties" and said the club had a zero tolerance for drug dealing in the venue.
Ms Hassell said she was "struggling" to make a prevention of further death report, adding: "I'm not naive enough to think people will stop taking recreational drugs."