A teenager died after experimenting with a 'legal high' drug he ordered online marked 'not for human consumption'.
Adam Hunt, 18, told a friend he planned to take the psychoactive substance AMT at his home in Southampton, Hampshire, because he believed it had the same effects as ecstasy.
Adam's mother, Bernadette Fagan, returned home from work to hear her son calling for help from his bedroom.
She told the inquest into his death: "He was sweating and shaking. She immediately phoned for help and ambulance staff arrived a short while later and took Adam to hospital."
The teenager died four days later at Southampton General Hospital after being put in a medically-induced coma.
The inquest heard police discovered Adam had researched AMT and legal highs on the internet after his computer was seized.
Packets containing the drugs were also found, with each bearing a 'not for human consumption' warning.
Pathologist Dr Brian Green said a post mortem found he had died of multiple organ failure caused by taking almost 1g of the drug, Alpha Methyltryptamine.
He said: "One of the problems of buying medicines from unregulated manufacturers is the individual awareness of the concentration of the substance in the drug provided may bear no resemblance to the actual concentration, that puts an even greater risk in the ingestion of substances that are unregulated."
Coroner Keith Wiseman ruled Adam's death had been accidentally caused by experimenting with the drug, before warning: "Anyone taking this kind of drug in any kind of quantity is potentially walking into the unknown, into disaster really."
Speaking to Adam's family, he added: "It was sadly an experimentation gone wrong. I would like to express my very sincere condolences to everyone."
Mr Wiseman also advised parents to raise the issue with their children, especially if they were behaving unusually.
After the inquest Detective Sergeant Jeremy Boughay said: "The concern is that people have the perception that as they are marketed under the term 'legal high' that they will be safe and the point we are trying to make is that there's no process to ensure what is written on the packet is what's inside as they are not regulated.
"They are sold under the term 'legal high' when in fact they pose more of a danger than a lot of other legally available substances on the market."