And yet teenagers and young people that throw back a standard 500mL energy drink are doing just that.

On the Australian market, sales of energy drinks have risen by an average of 6.7 per cent every year since 2010.

Just one 500mL can of Rockstar Punched Energy + Guava tropical guava flavour ($2.60 at Coles) contains 21 teaspoons or 83.5 grams of sugar, and 160 milligrams of caffeine.

Coca-Cola Amatil's 500ml Mother ($2.80) contains 13 teaspoons of sugar and 160mg of caffeine, while 250mL cans of Red Bull ($2.85) and Mother ($2.86) serve up seven teaspoons of sugar and 80mg of caffeine

The high levels of caffeine have made such beverages a favourite among young people, particularly students preparing for their HSC exams.

Their popularity has prompted a coalition of 13 leading health and community organisations to issue a warning that about possible health risks.

"[Energy drinks] are a risky drink choice...especially for students who may be consuming several a day during this stressful end of year exam period," said Craig Sinclair, public health committee chair of the Cancer Council Australia.

The organisation has joined Diabetes Australia, the Heart Foundation, Nutrition Australia and others for the Rethink Sugary Drink Campaign, which calls for a 20 per cent tax on sugary drinks, a public education campaign and tougher sale restrictions in schools and sports centres.

"If consumed regularly the high sugar content in energy drinks can lead to weight gain and obesity, increasing your risk of heart and kidney disease, type 2 diabetes, stroke and some cancer," Mr Sinclair said.

Dr Peter Alldritt, of the Australian Dental Association, said energy drinks also contributed heavily to "tooth decay and erosion."

As a teacher at a co-ed private school in Sydney last year, Emily* witnessed at least two students who developed "definite addictions" to energy drinks in their HSC year.

"For one student it turned into a cycle where he was unable to sleep, so he was drinking more and more. Eventually he was drinking about six 250mL cans a day."

Emily said a second student, who was drinking up to three cans a day, was "helped to come off them," by another teacher, but doing so left him unable to work.

"It was a definite addiction for both students. They didn't know how to, or didn't want to stop."

The short-term effects of energy drinks include alertness, stimulation of the nervous system and an increased heart rate, while excessive consumption can cause insomnia, nausea, vomiting and heart palpitations.

In both 2014 and 2015 the NSW Poisons Information Centre hotline received more than 40 calls related to energy drinks.

Energy drink sales in Australia and New Zealand increased from 34.5 million litres in 2001 to 155.6 million litres in 2010, according to the Australian Bureau of Statistics.

However a spokesman for the Australian Beverages Council said, ABS data also confirmed energy drinks represented less than 0.4 per cent of total intake of all non-alcoholic, non-dairy beverages among 14 to 18-year-olds.
 
"In this demographic, just 1.7 per cent consumed energy drinks," he said, adding that Australia had "some of the toughest regulations in the world."

While the industry does not make drinks available in secondary schools, the Rethink Sugary Drink Campaign argues that heavy marketing tactics do target young people.

Mr Sinclair said major brands like Red Bull, Monster and Rockstar "pour enormous amounts of money into partnerships with activities young people enjoy," like extreme sports, music festivals, and Schoolies-related events.

A spokesperson for Frucor, the manufacturer of Rockstar, said labelling on its cans recommended no more than one can was consumed each day.

"Rockstar supports events aimed at consumers aged older than 18. We do not provide samples to anyone aged 18 or under."

Coca-Cola Amatil said Mother was not marketed to children and labelling on all cans recommended a maximum daily intake of 500mL.

"An older teen's decision to drink an energy drink is akin to deciding to have a cup of coffee. They are old enough to make that decision for themselves."

*Name changed to protect student privacy.

smh.com.au