Which Drugs Are the Most Addictive?

By May Wilkerson 03/10/16

"Addictiveness" is certainly hard to quantify—but a panel of addiction experts decided to take a shot at answering the complex question. 

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Which Drugs Are the Most Addictive?
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Some drugs are more physically addictive, some are more psychologically addictive, and many are a combination of the two.

But which drugs are the most addictive? It depends. The potential for a drug to get someone hooked relies on a variety of factors including how much harm it causes, its street value, how much it activates your brain’s dopamine system, how much pleasure people experience while taking it, withdrawal symptoms, and how easily people report getting hooked.

Because of these many complex factors, it’s difficult to quantify addictiveness. And some researchers argue that no drug is addictive 100% of the time, as it depends on the individual who takes it.

In 2007, David Nutt and his colleagues asked a panel of experts to rank the addictive nature of various recreational drugs. Their answers, below, provide a rough estimate of which drugs are most likely to get you hooked. Though, of course, it depends on you and your circumstances.

These were their top five, from most to least addictive:

1. Heroin

Nutt’s panel of experts ranked heroin as the number one most addictive drug, scoring it 2.5 out of the maximum score of 3. The opiate-based drug causes dopamine levels in the brain to surge by up to 200% in study animals. 

Heroin is also quite dangerous, since a potentially fatal dosage is only five times greater than the amount required to get high. Heroin has been ranked the second most harmful drug in terms of its damage to people who use it and to society as a whole. (See below for the most harmful drug. You may be surprised.)

2. Alcohol

Booze may be legal for adults in most parts of the world. But it’s still addictive, following only heroin in most likely to get you hooked, scoring 2.2 out of 3, according to Nutt’s panel of experts. In study animals, it boosted dopamine levels by 40-360%. Those levels seemed to rise even more as the animals consumed more alcohol.

An estimated 22% of people who consume alcohol will develop a dependence at some point in their lives. And it remains the most popular drug in the world—the World Health Organization (WHO) has estimated that 2 billion people drank alcohol in 2002. It’s also the most dangerous, many experts have agreed. According to WHO, more than 3 million people died in 2012 from health issues related to drinking. 

3. Cocaine

In third place, according to the panel, is cocaine. This drug interferes with the way your brain uses dopamine to carry messages between neurons. Essentially, cocaine prevents neurons from turning the dopamine signal off, so your brain is flooded with the “feel good” chemical. In study animals, researchers found cocaine caused dopamine levels to more than triple.

An estimated 14-20 million people across the globe use cocaine, according to the United Nations World Drug Report. And roughly 21% of people who try the drug will become dependent on it at some point in their lives. The drug’s harms depends on the form in which it’s used. Experts have ranked crack cocaine (or freebase form) as the third most dangerous drug. Powdered cocaine, which causes a less intense high, has been ranked as the fifth most dangerous.

4. Barbiturates

Nutt’s panel of experts rated barbiturates as the fourth most addictive substance. Barbiturates, aka “downers,” are a class of prescription drugs that were initially intended to treat anxiety and insomnia. They work by effectively shutting down various brain regions of the brain, and in low doses, they can cause euphoria. But in high doses, they can be fatal, since they suppress air flow to the lungs.

Barbiturates used to be more readily available by prescription, and dependence was fairly common. However, dependence on the drugs has decreased significantly since they have been replaced by other, less addictive drugs to treat anxiety and induce sleep. 

5. Nicotine

Nicotine is the main reason tobacco products (including cigarettes) are so addictive. When you smoke a cigarette, nicotine is rapidly absorbed by the lungs and delivered to the brain, releasing dopamine. Nutt’s panel ranked nicotine (tobacco) as only the 12th most addictive substance, but it is still one of the most common addictive substances in the world. Studies on rats found that when nicotine is released directly into their bloodstream, it causes dopamine levels in the brain’s reward system to rise by about 25-40%.

More than two-thirds of Americans who have smoked a cigarette reported becoming addicted at some point in their lives. And in 2002, the WHO estimated there were more than 1 billion smokers across the world, and that tobacco is predicted to cause more than 8 million deaths annually by 2030.

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May Wilkerson is a writer, comic and Managing Editor @someecards. Co-host of the podcast Crazy; In Bed w/ @alyssalimp. She is also the top Google result for "insufferable lunatic." Follow this insufferable lunatic on Twitter.

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