A 35-year-old man died at Bestival music festival after slashing his arms while suffering a paranoid reaction to what he believed was a "legal high".
Daniel Parks took the substance 'Magic Crystals' along with his wife at the Isle of Wight event last year.
Unbeknown to the couple, they contained the banned drug 4-Methylethcathinone, an inquest heard today.
Mr Parks, from Royal Tunbridge Wells, Kent, was described as having a paranoid reaction to the drug and he was found by his wife locked in the toilet of their campervan in a distressed state having inflicted several wounds to his arms with a kitchen knife.
He was taken to St Mary's Hospital in Newport where he died as a result of loss of blood caused by the deep cuts to his arms.
Recording a narrative verdict, Isle of Wight Coroner Caroline Sumeray said: "He had purchased what he believed to be 'legal highs' via the internet prior to attending the festival.
"Unbeknownst to him, the 'Magic Crystals' which he purchased were, in fact, a prohibited substance, believed to 4-Methylethcathinone.
"Daniel had consumed legal highs on a number of occasions prior to this event, notably in April 2012 when he suffered an adverse reaction resulting in an emergency admission to accident and emergency, but he self-discharged prior to seeing any doctor on that occasion.
"Daniel and his wife consumed these 'Magic Crystals' on Thursday, September 6, 2012 whiilst at the Bestival festival and Daniel suffered a paranoid reaction.
"Daniel's mood was subdued thereafter and had improved by Saturday, September 8, 2012 when he enjoyed some cider and pizza.
"Daniel and his wife retired to their campervan at 9.30 pm that evening and his wife fell asleep.
"Daniel locked himself in the campervan's toilet/shower cubicle and inflicted a number of serious wounds to both lower arms with a large sharp kitchen knife.
"Daniel's wife discovered Daniel in a state of distress and summoned help. Daniel was taken to St Mary's Hospital where efforts were made to resuscitate him, however he died of hypovolaemic shock secondary to deep cuts to both lower arms at 10.32 am on September 9, 2012."