Lachlan Foote (pictured) consumed his caffeine-laden shake after he returned home from a fairly tame night out with his some of his friends

A healthy young musician suddenly died from a caffeine overdose after drinking a protein shake.

Lachlan Foote was one day shy of his 22nd birthday when his parents found him dead on the bathroom floor of his family's home in the Blue Mountains west of Sydney on New Year's Day in 2018.

Taking to Facebook on Sunday, Lachlan's father Nigel Foote spoke candidly about his son's death in the hope it might possibly 'save someone else's life'.

A coroner's report last week concluded Lachlan died of unknowingly ingesting a lethal amount of caffeine, Mr Foote wrote.

The 21-year-old inadvertently overloaded a protein shake with too much pure caffeine - a teaspoon of which can be equivalent of up to 50 cups of coffee.

In a chilling final message posted to a Facebook group on the night he died, the usually healthy 21-year-old revealed his bedtime protein shake had tasted bitter.

'I think my protein powder has gone off. Just made an anti hangover / workout shake and it tasted awful,' Lachlan wrote at 2.07am.

'Anyway … night lads. Cya in the morning.'

Within a few hours, Lachlan was found dead.

His family now want to share their story as a warning to others, with his father claiming it only takes one teaspoon of the powder to create lethal consequences.

Caffeine powder is widely marketed as a diet supplement and is commonly added to energy drinks and shakes, but combining it with other legal drugs can be lethal.

According to the Alcohol and Drug Foundation, consuming caffeine with alcohol places 'enormous strain on the body' and may even mask some of alcohol's effects.

Lachlan consumed his caffeine-laden shake after he returned home from a fairly tame night out with his some of his friends.

While it remains a mystery exactly where the 21-year-old got the caffeine powder, his father believes Lachlan may have got it from a friend or colleague.

In a chilling final message posted to a Facebook group on the night he died, the usually healthy 21-year-old revealed his bedtime protein shake had tasted bitter (recreated message)

'It's very likely that Lachlan never got to read the warning label on the packet and was unaware of its potency,' he wrote on Facebook.

The devastated father recalled how excruciating it was to wait to hear back from the coroner.

Mr Foote stated blood results also revealed Lachlan had no illicit substances in his system and he'd likely only had a few drinks, given his blood alcohol level was below 0.05.

The bereaved father also stated in the Facebook post he doesn't blame whoever shared the caffeine powder with Lachlan, given they also probably had no idea how dangerous it can be.

'It's scandalous that this product has not been banned in Australia,' he wrote.

According to a Cornell University fact sheet, just one teaspoon of pure caffeine powder contains 5000 milligrams of caffeine, which could be lethal.

'Mixing two spoonfuls of the powder into a drink is the same as drinking 70 Red Bulls at once, which could kill you,' the fact sheet stated.