Measuring the ‘addictiveness’ of an individual drug is a difficult process. Many discussions of this area refer to a study published in The Lancet that was led by Professor David Nutt in 2007.

The study aimed to quantify the harms done by different substances in the UK to both individuals and society. The study proved controversial, with many tabloids claiming it was wrong to rank alcohol as ‘more harmful’ than crack or heroin for example.

Alcohol was ranked the most harmful substance overall from the list of 20 considered but this took into account the widespread usage of alcohol as a legal and generally socially acceptable drug.

As well as being addictive, alcohol is associated with numerous health problems and social issues such as violence and criminal behaviour.

Nicotine also ranked highly for similar reasons – because the overall impact on society was included and it is a fact that smoking kills more people than, say cocaine.

Anyone who has been an alcoholic or seen a loved one battle with this addiction will know that it can be extremely harmful to the individual but being the most harmful to society overall does not necessarily make it the most addictive drug in the world.

So what is the most addictive drug in the world? As part of the study, Nutt and a panel of experts did consider the addictiveness of the substances, based on levels of physical dependence, psychological dependence and the pleasure generated by the drug.

There are limitations in this approach, however. Any scores were based on expert opinion rather than any sort of clinical tests that would show the most addicting drugs in the world. Only 20 substances were considered and new ‘designer’ and prescription drugs are constantly being introduced.

There is no definitive ‘most addictive drug in the world’ wiki that conclusively shows which drugs are the most addictive but most of these ten featured prominently in the Lancet study and would probably feature in most organisations’ up to date list of the most addictive drugs in the world.



Heroin would probably top most lists as the single most addictive illegal drug in the world. It also scored highest for dependency in the Lancet study. Incidentally, heroin was ranked the highest in terms of harm to the individual using it, and second-highest after alcohol in terms of overall harm to society. The American Society of Addiction Medicine (ASAM) has estimated that around a quarter of people who experimented with heroin end up addicted to the drug.


Crack cocaine

Crack cocaine, also known simply as crack, is a highly addictive ‘free base’ form of cocaine made by mixing powdered cocaine with baking soda. The structure means it can be smoked rather than snorted. This allows it to enter the bloodstream more quickly and results in an intense but short-lived high. The Manual of Adolescent Substance Abuse Treatment says it the most addictive form of cocaine.



Also commonly known as crystal meth, can be seen as a more addictive version of ‘regular’ amphetamine, in a similar way to crack’s relationship to cocaine. When used, the brain ‘lights up’ with dopamine and norepinephrine. It produces another intense high but the brain quickly begins to build up a tolerance, leading to more powerful cravings and greater consumption.



This is a family of psychoactive drugs known as depressants because they depress or slow down mental and bodily functions. Well-known types include diazepam (first branded and often known as Valium) and alprazolam (Xanax). They have legitimate medicinal uses for conditions such as anxiety but can be abused and are known to be addictive.



Alcohol is one of the earliest and most commonly used recreational substances in human history. In many places, it is freely available and socially acceptable but alcohol is still one of the most addicting drugs in the world. It depresses the central nervous system and can relieve anxiety and loosen inhibitions, helping the drinker to relax. Over time tolerance can build, meaning the drinker needs to consume more to get the same effect and eventually to even feel normal.



Cocaine is a stimulant that can produce feelings of euphoria, increased alertness and energy. It can also have dangerous effects such as rapid heart rate and increased blood pressure, however. It increases levels of available dopamine in the brain by preventing the chemical from being recycled back into cells. This can quickly lead to the brain being less sensitive to dopamine, meaning the user needs more and more cocaine for the same effect, often leading to dangerous ‘binges’.



The Lancet study’s finding that nicotine’s addictiveness could be compared to illegal drugs like cocaine caused a lot of controversy at the time. Nicotine is certainly highly addictive however and withdrawal symptoms can include powerful cravings, irritability, trouble sleeping and more. Burning tobacco and additives like tar are the elements of smoking that cause physical harm, but it’s the nicotine that keeps you coming back for more.



Methadone is commonly used as a substitute for heroin and other opioids. It is less harmful than heroin and easier to administer in controlled doses but is still an addictive substance. Some critics argue that methadone programmes merely swap one addiction for another but studies have shown it can be effective in stabilising heroin addicts and helping them to come off the more harmful drug.



Amphetamines are a stimulant family of drugs that can produce a burst of energy and release the ‘pleasure chemical’ dopamine. This positive ‘reward’ feeling can be highly addictive. There are medical types of amphetamine that can be used to treat a range of illnesses and disorders but misuse can produce negative or dangerous effects including heart problems, paranoia and increased levels of aggression.



Like benzodiazepines, barbiturates are a class of prescription medications that can be used legitimately but are still generally considered one of the ten most addictive drugs in the world. They can cause drowsiness and a feeling of relaxation but repeated use can lead to an increase intolerance. Overdoses can be fatal and withdrawal symptoms can be extreme.


  • [1] The Lancet -