04/03/2016 2:07 PM AEDT | Updated 15/07/2016 12:51 PM AEST

The Five Most Addictive Drugs, And Whether Ranking Them Actually Does Any Good

andrewsafonov via Getty Images

Ever wondered what the most addictive drug is?

In 2007, UK drug expert David Nutt and his colleagues asked a panel of addiction experts to score each drug by how addictive it was.

UK neuroscience and psychology lecturer, Dr Eric Bowman, has revisited this original research to construct a list of the five most addictive drugs.

But is a ranking system helpful when it comes to preventing and treating addiction? And how did Nutt come to create such a list?

1. Heroin

Heroin’s sometimes prescribed as a pain medication in certain countries, but its most notorious use is as a recreational opiate.

Heroin induces euphoria in those that take it, though tolerance to the drug quickly increases, meaning users have to take higher and higher amounts to get the same feeling.

As well as being ranked the most addictive drug by Nutt, it’s also considered to be the second most harmful, Dr Bowman writes in The Conversation.

2. Alcohol

Alcohol comes in at second on the list of addictive drugs. It’s a depressant that causes some euphoria, but in larger doses slows body function, induces lethargy, and can knock you unconscious.

It also causes cancer -- as it’s classified as a group one carcinogen by the International Agency for Research on Cancer.

“The WHO has estimated that two billion people used alcohol in 2002 and more than three million people died in 2012 due to damage to the body caused by drinking. Alcohol has been ranked as the most damaging drug by other experts, too,” Bowman said.

3. Cocaine

Mentally, those who take cocaine feel euphoric, energised or agitated. Physically, their heart’s beating much faster than usual, and especially high doses increase blood pressure substantially.

Twenty-one percent of people who try cocaine will become dependent on it, and crack cocaine is ranked as the third most damaging drug in the world. Just under 10 percent of Australians have used cocaine at some point in their life.

4. Downers

Downers, or barbiturates, shut down brain function to make you feel happier. They’re dangerous because high doses of barbiturates can be lethal because they suppress breathing.

Though Nutt and his colleagues listed downers as fourth on their list of addictive drugs, Bowman suggests they’re less widely-used in modern times as their prescription availability is far more limited.

5. Nicotine

About 13 percent of Australian adults smoke daily in Australia. It’s predicted that more than eight million people will be killed by tobacco annually by 2030.

Though Nutt ranked nicotine the 12th most addictive substance, Dr Bowman has elevated it to fifth due to its widespread use and impact.

“The fact that so many people smoke in spite of the known health consequences is a measure of nicotine’s potential to cause dependence,” he said in a comment on his article.

Is a ranking like this credible?

Nutt’s original study has been heavily criticised in some quarters of the drug research field because it draws from the opinions of a panel of experts, rather than a more scientific measure of addiction.

Director of the National Drug and Alcohol Research Centre, Professor Michael Farrell, told the Huffington Post Australia that while some of the ideas in Nutt’s paper were useful, there were problems with ranking drugs by addiction and harmfulness.

“The problem comes when we say alcohol is more harmful than, say, cannabis,” Professor Farrell said.

“One of the issues in this is it’s not the drug itself, it’s how much is used, how many people use it.”

He said that while Nutt made the point that drugs like alcohol and nicotine were more harmful than commonly accepted in society, it didn’t necessarily aid the debate around the prevention and treatment of addiction.

“There’s been more heat than light from the debate around the paper at times,” he told HuffPost Australia.

What about meth?

It’s been found that almost 60,000 Australians between 15 and 24-years-old are using methamphetamines, with a new report revealing 35,000 of these users are dependent on the drug.

The report, published on Monday by the Medical Journal of Australia reveals almost 270,000 Australians aged between 15 and 54-years-old are regular methamphetamine users, with more than half classified as dependent.

Yet the original ranking from Nutt and his colleagues excludes meth, potentially due to its low availability in the UK last decade.

Professor Farrell says most Australians would rank methamphetamine as highly addictive and harmful.

“Most Australians would rank it at the top end. I’d imagine it would come in well up the scale,” he told HuffPost Australia.