Caffeine is so dangerous for our health that coffee, cola and other caffeinated products should carry warnings on the packaging, according to a leading expert.
Dr Jack James, who is the editor-in-chief of the Journal of Caffeine Research, wrote an editorial saying caffeine has caused "untimely deaths" and that it's potentially lethal.
Dr James, who is also the head of psychology at Reykjavik University in Iceland, said the stimulant is being added to increasing numbers of energy drinks, alcoholic drinks, soft drinks, chewing gum, cookies, yoghurt and flavoured milks, which is causing people to consume more than they realise.
It's also often added to bulk up illicit drugs, as well as over-the-counter weight loss pills, mints and soaps.
He said the health risks are so great that it should be taxed and labelled like alcohol and cigarettes, and sales to children should be limited.
Dr James said caffeine was a contributing factor in 6309 cases notified to the American National Poison Data System in 2011. He also said the number of US emergency room visits linked with energy drinks increased by 36 percent between 2010 and 2011.
Young people are particularly at risk — when caffeine is mixed with alcohol, the chances of people having unprotected sex, committing or being a victim of sexual assault, drink driving and being violent is greater.
Other studies have suggested that children who have caffeine are more likely to experiment with alcohol, cigarettes and drugs when they're older.
But Kellie Billinski, a spokesperson for the Dietitians Association told MSN NZ that Dr James's piece is unnecessarily alarmist.
"There is not a lot of other evidence [to support this]," she said.
"Too much of anything is not a good thing — and there are upper limits that we shouldn't exceed because too much caffeine can cause an elevated heart rate and cause people to become anxious and irritable, or have difficulty sleeping."
The National Health and Medical Research Council suggests adults limit themselves to 210mg a day, which is the equivalent of two strong cups of coffee or three to four instant coffees.
"If you are having difficulty sleeping you might have had too much and if you are waking up with a headache because you haven't had a cup of coffee, you've probably got a dependence on it. People also develop a tolerance, so if you find you need eight cups a day and don't get the same buzz from it, you are probably having too much."
Billinski said there are some studies that suggest it could have health benefits.
"It can make people feel more alert and it does have antioxidants," she said.
Dr James's editorial "Death by Caffeine: How Many Caffeine-related Fatalities and Near-misses Must There Be Before We Regulate?" comes after the US Food and Drug Administration announced last year that they were investigating Monster Energy drinks after reports that five deaths had been linked with it.