The most addictive drugs are heroin, cocaine and nicotine, followed by barbiturates and alcohol, according to a panel of addiction experts.
The addictive quality of drugs are measured by both its effect on the body and the effects it has on society.
For example, researchers look at how strongly the drug affects the brain's dopamine system or the strength of its withdrawal symptoms.
They also consider the drugs street value and how pleasurable users report it to be.
When Professor David Nutt, director of psychopharmacology in the Division of Brain Sciences at Imperial College, London, asked a panel of addiction experts to rank which drugs they believed were most addictive, they said the most addictive drugs were heroin, cocaine, nicotine, barbiturates and alcohol, The Conversation reports.
Cocaine hits the addiction trifecta: it causes the brain's dopamine levels to increase by up to 200 per cent in laboratory experiments using animals, it causes brutal withdrawal symptoms and has a cheap street value.
It is also one of the most dangerous drugs, because the dose that can cause death is only five times greater than that required to get high.
In November, Ireland declared it would move towards decriminalising small amounts of substances including heroin, cocaine and cannabis as part of a "radical cultural shift".
Cocaine directly interferes with the brain's dopamine system, preventing neurons from turning the dopamine signal off, resulting in an abnormal activation of the brain's reward pathways.
In laboratory experiments using animals, cocaine caused dopamine levels to rise more than three times above the normal level.
Other experts have ranked crack cocaine as the third most damaging drug.
The main addictive ingredient in tobacco, nicotine is rapidly absorbed by the lungs and delivered to the brain when someone smokes a cigarette.
On non-smoking day (9 March), researchers released a video showing the difference in lung capacity between a smoker and non-smoker.
Initially used to treat anxiety and induce sleep, barbiturates interfere with chemical signalling in the brain, shutting down various brain regions.
At low doses, they can cause euphoria, but higher doses can be lethal because they suppress breathing.
While barbiturate dependence was high when the drugs were easily available on prescription, their use has declined as other drugs have replaced them.
One of the world's most ubiquitous drugs, alcohol is capable of increasing dopamine levels in the brain of animals by 40-360 per cent, the researchers found. The more the animals drank, the higher dopamine levels rose.
Public Health England estimates that 10.8 million people drink at risky levels and 1.6 million are dependent on alcohol.
A study recently claimed almost 70 per cent of alcohol sold in England is consumed by drinkers who are risking their health.
World's 10 most deadly street drugs
World's 10 most deadly street drugs
1/10 10. Purple Drank
One of the more unusual drugs around at the moment, purple drank was popularised in 90s hip hop culture, with the likes of Jay Z and Big Moe all mentioning it in their songs. It is a concoction of soda water, sweets and cold medicine, and is drunk due to cold medicines high codeine content, which gives the user a woozy feeling. However it can also cause respiratory issues and heart failure
2/10 9. Scopolamine
Scopolamine is a derivative from the nightshade plant found in the Northern Indian region of South America (Ecuador, Colombia and Venezuela). It is generally found in a refined powder form, but can also be found as a tea. The drug is more often used by criminals due its high toxicity level (one gram is believed to be able to kill up to 20 people) making it a strong poison. However, it is also believed that the drug is blown into the faces of unexpecting victims, later causing them to lose all sense of self-control and becoming incapable of forming memories during the time they are under the influence of the drug. This tactic has reportedly been used by gangs in Colombia where there have been reports of people using scopolamine as way to convince victims to rob their own homes
3/10 8. Heroin
Founded in 1874 by C. R. Alder Wright, heroin is one of the world’s oldest drugs. Originally it was prescribed as a strong painkiller used to treat chronic pain and physical trauma. However in 1971 it was made illegal under the Misuse of Drugs Act. Since then it has become one of the most destructive substances in the world, tearing apart communities and destroying families. The side effects of heroin include inflammation of the gums, cold sweats, a weak immune system, muscular weakness and insomnia. It can also damage blood vessels which can later cause gangrene if left untreated
4/10 7. Crack cocaine
Crack cocaine first came about in the 1980’s when cocaine became a widespread commodity within the drug trafficking world. Originally cocaine would have attracted a high price tag due to its rarity and difficulty to produce, but once it became more widespread the price dropped significantly. This resulted in drug dealers forming their cocaine into rock like shapes by using baking soda as a way of distilling the powder down into rock form. People were doing this because it allowed for them to sell cocaine at a lower quantity and to a higher number of people. The side effects of crack cocaine include liver, kidney and lung damage, as well as permanent damage to blood vessels, which can often lead to heart attacks, strokes, and ultimately death
5/10 6. Crystal meth
Not just famous because of a certain Walter H White, but also because it is one of the most destructive drugs in the world. First developed in 1887, it became widely used during the Second World War when both sides would give it to their troops to keep them awake. It is also believed that the Japanese gave it to their Kamikaze pilots before their suicide missions. After the war crystal meth was prescribed as a diet aid and remained legal until the 1970s. Since then it has fallen into the hands of Mexican gangs and has become a worldwide phenomenon, spreading throughout Europe and Asia. The effects of crystal meth are devastating. In the short-term users will become sleep depraved and anxious, and in the long-term it will cause their flesh to sink, as well as brain damage and damage of the blood vessels
6/10 5. AH-7921
AH-7921 is a synthetic opioid that was previously available to legally purchase online from vendors until it became a Class A in January 2015. The drug is believed to have 80% of the potency of morphine, and became known as the ‘legal heroin’. While there has only been one death related to AH-7921 in the UK, it is believed to be highly dangerous and capable of causing respiratory arrest and gangrene
7/10 4. Flakka
Flakka is a stimulant with a similar chemical make-up to the amphetamine-like drug found in bath salts. While the drug was originally marketed as a legal high alternative to ecstasy, the effects are significantly different. The user will feel an elevated heart rate, enhanced emotions, and, if enough is digested, strong hallucinations. The drug can cause permanent psychological damage due to it affecting the mood regulating neurons that keep the mind’s serotonin and dopamine in check, as well as possibly causing heart failure
8/10 3. Bath salts
Bath salts are a synthetic crystalline drug that is prevalent in the US. While they may sound harmless, they certainly aren’t the sort of salts you drop into a warm bath when having a relaxing night in, they are most similar to mephedrone, and have recently been featured throughout social media due to the ‘zombification’ of its. The name comes from the fact that the drug was originally sold online, and widely disguised as bath salts. The side effects include unusual psychiatric behaviour, psychosis, panic attacks and violent behaviour, as well as the possibility of a heart attack and an elevated body temperature
9/10 2. Whoonga
Whoonga is a combination of antiretroviral drugs, used to treat HIV, and various cutting agents such as detergents and poisons. The drug is widely available in South Africa due to South Africa’s high rate of HIV sufferers, and is believed to be popular due to how cheap it is when compared to prescribed antiretrovirals. The drug is highly addictive and can cause major health issues such as internal bleeding, stomach ulcers and ultimately death
10/10 1. Krokodil
Krokodil is Russia’s secret addiction. It is believed that over one million Russians are addicted to the drug. Users of krokodil are attracted to the drug due to its low price; it is sold at £20 a gram while heroin is sold for £60. However, krokodil is considered more dangerous than heroin because it is often homemade, with ingredients including painkillers, iodine, lighter fluid and industrial cleaning agents. This chemical make-up makes the drug highly dangerous and likely to cause gangrene, and eventually rotting of the flesh
Mark Shepperd, managing director of public health for substance misuse charity Turning Point, told The Independent: “Misuse of drugs of any type can be damaging to health and have a devastating impact on someone’s family life, their work and on wider society.
"Services set up to deal with substance misuse must be flexible enough to take account of the needs of individuals and changing trends. They must also be able to support groups of drug users that wouldn’t typically think to go to a ‘drug service’, for example those affected by club drugs.
"We must also remember that people do recover if they are given the right help and treatment. It's vital that support is provided within communities so as to prevent a substance misuse issue escalating and to break down the stigma associated with seeking help."Reuse content