A father-of-two died after he accidentally “necked” a drink made with caffeine powder that was as strong as 200 cups of coffee, an inquest heard.
Personal trainer Thomas Mansfield, 29, ordered a 100g packet of caffeine powder to make supplement drinks at his family home but accidentally made a mixture containing seven times the recommended dose.
His heartbroken widow Suzannah said her "really healthy" husband began "clutching his chest" on the sofa after downing the drink.
An inquest heard Mr Mansfield, of Colwyn Bay, North Wales, had ordered the powder from supplement company Blackburn Distributions.
The recommended serving of the powder 60 to 300mg twice a day – but Mr Mansfield's digital scale had a starting weight of 2g.
The inquest heard Mr Mansfield was "likely aiming for a mid range serving" but instead drank up to 5g of the powder.
Mr Mansfield, who also worked as a security guard, first took a sip of the mixture before he "necked the remainder of the drink”.
A post-mortem examination found he had 392mg of caffeine per litre of blood – the equivalent of up to 200 cups of coffee.
The inquest heard death can be caused by levels at 78mg per litre of blood or higher.
Mrs Mansfield said she saw her husband frothing at the mouth just moments after drinking the solution and she ran outside to get help from neighbours and nearby family members before an ambulance was called.
The inquest heard paramedics arrived within minutes to use a defibrillator due to Mr Mansfield's "grossly abnormal" heart rhythm.
He was rushed to Glan Clwyd hospital after going into cardiac arrest, but he was pronounced dead at 4pm on 5 January last year.
Mr Mansfield’s medical cause of death was given as caffeine toxicity.
Senior coroner John Gittins recorded Mr Mansfield's death as misadventure due to the unintended result in consuming the caffeine powder.
He added he had been "reassured" that action had been taken by the brand to provide a measuring scoop and an A4 instruction sheet.
The inquest heard the instructions and warnings on the packet were not in breach of regulations at the time.
Writing on social media, Mrs Mansfield said she was "absolutely heartbroken" by the tragedy.
She said: "He was my whole life I'll never get over this. You were my life Tom."
Self-employed Mr Mansfield ran fitness classes with his personal training business and used the motto: "With you every step of the way."