The death of a 21-year-old man has prompted a coroner to call for a Home Office review into the sale of an illegal diet pill.
Vaidotas Gerbutavicius took 20 pills in March 2018 and told a police officer "he felt like his body was burning".
After consuming dinitrophenol (DNP), which is also used in explosives, Mr Gerbutavicius told his father he would be dead within the hour.
Senior coroner Nadia Persaud said its continued sale online needed reviewing.
DNP was marketed as a diet pill in the US in the 1930s but selling it for human consumption has since been made illegal.
It has a variety of industrial uses, including as a photographic chemical, a fertiliser and in the manufacturing of dyes and explosives.
Those who take the drug experience an increase in temperature and metabolic rate, which can prove fatal.
Within an hour of being admitted to hospital, Mr Gerbutavicius, from Newham, was put in an induced coma and given CPR but died from to a cardiac arrest on 10 March.
Ms Pasaud told Walthamstow Coroners' Court on Tuesday: "The current legislation is wholly inadequate and in no way an appropriate means by which to deal with offences that can result in the deaths of those who consume DNP.
"Those affected are often young and vulnerable people."
The inquest heard Mr Gerbutavicius had been overweight until he was 18 but had started to lose weight in 2016, which his family thought was a result of him growing older and having a new girlfriend.
However, they learned on the day of his death he had been taking slimming pills, which he purchased from a US seller using the dark web.
Ruling the cause of his death as consumption of dinitrophenol (DNP), Ms Persaud called it an "extremely harmful substance" which has "no antidote available".
She ruled out suicide as the cause of 21-year-old's death because he appeared to have acted "impulsively" following a disagreement with his girlfriend, and had been planning for his future, the senior coroner said.
Mr Gerbutavicius' father Andrius told the BBC he was "still in shock" over his son's death.
"You never expect someone to die from slimming pills," he said.
He has called for tighter controls on sales of DNP, adding that otherwise "more deaths will follow".
In February Barry Clint Wright, of North Carolina in the US, was jailed for selling dinitrophenol (DNP) as an unlawful drug.