An estimated 23 million Americans and nearly 30 million people worldwide are addicted to a substance—from alcohol to prescription medications to illicit drugs. Addiction is the unintended outcome of misusing or overusing an addictive substance. While there is much debate over the role that free will or choice plays in addiction, it can certainly be argued that no one who takes a drink, drug or prescription medication sets out to become an addict. More likely, they take the substance to find a way to feel good (or at least better), relieve pain, forget their problems or numb difficult feelings. If that substance is highly addictive, the substance is more likely to be repeated.
Addictive Substances and the Road to Addiction
With repeated use of addictive substances comes greater risk for addiction. The more addictive the substance, the more likely it is that a person rapidly progresses from physical tolerance and dependence to addiction—requiring increased doses to achieve the same effects, followed by cravings and withdrawal symptoms when they try to stop. This progression is even more likely if a person has other contributing factors of addiction, including:
- Heredity (family history of addiction)
- Anxiety, depression or another mental health condition
- Childhood abuse or lack of supervision/family involvement
- Poor social skills and/or peer pressure
In many cases, addiction occurs before a person realizes they have lost control. The stigma of addiction often shames them into hiding their problem, preventing them from seeking help to stop the cycle of substance abuse. As the addiction continues, denial and other addiction-related behaviors set in, making treatment and recovery more challenging, though not impossible.
12 Highly Addictive Substances
Which drugs are the most addictive? Answers to this question vary depending on which research team or addiction expert you speak with and their estimation of a substance’s impact on the brain’s reward system, the body’s nervous system, how quickly a person can become hooked on it, and/or how challenging or dangerous the substance’s withdrawal symptoms can be. We have used their general criteria to create a list of the 12 most highly addictive substances in the world, starting with the “most addictive” at the top:
1. Opiates (heroin, opium, morphine and others)
Most experts agree that heroin is one of the most highly addictive drugs, though most drugs in the opiate category should probably share the top position on the list. In research studies, heroin is shown to increase levels of “feel good” neurotransmitters in the brain’s reward system by nearly 200%, causing a euphoria that makes it extremely addictive. Derived from opium, which is extracted from poppy seeds, opium is produced illicitly from poppies harvested in Afghanistan, Burma and Colombia, while most opiate medications are produced legally from poppies harvested in India, Turkey and Australia.
2. Opioids (oxycodone, hydrocodone, fentanyl and others)
Opioids are synthetic opiates. According to the World Drug Report, opioids were the most harmful drug type in 2017, accounting for 70% of the negative health impact associated with substance abuse worldwide. Prescription opioids, like OxyContin and Vicodin, can increase levels of “feel good” neurotransmitters in the brain’s reward system, though not as dramatically as heroin does unless a person significantly increases their dosage. A prescribed dosage typically ranges from 20 to 50 MME (morphine milligram equivalents), but it was found that 1 in 32 patients who died of opioid-related overdose in past years had increased their daily dose to more than 200 MME. Many people who become addicted to prescription opioids later turn to illicit opiates like heroin, which produce even more powerfully euphoric effects at a lower price.
3. Crack (crack cocaine)
A version of cocaine that is made by mixing baking soda or ammonia with powdered cocaine, crack is typically smoked. Crack has a lower purity level than cocaine, but inhalation of the crack smoke produces a completely different result—the “high” is more intense and happens more rapidly. A crack high is all-consuming, producing euphoria, increased energy and self-confidence—feelings that last roughly 10 minutes. The dramatic but short-lived effects lead to an intense craving for more. Thus, repeated use, addiction and withdrawal symptoms can set in quickly. Withdrawal symptoms may include extreme agitation, depression and insomnia, which drive the user to seek more of the drug.
4. Nicotine (tobacco)
It is estimated that more than 1 billion people worldwide smoke cigarettes and a majority of them are addicted to the nicotine in the tobacco. Addiction occurs because when you smoke a cigarette, the nicotine and other addictive additives in the tobacco absorb quickly into the bloodstream, reaching your brain within seconds and impacting the acetylcholine receptors to cause an adrenaline release. The adrenaline surge gives you a lift in alertness, mood and energy. The effects fade quickly, resulting in fatigue and a mild depression, prompting the desire for another cigarette and a lift from the nicotine. Continued smoking causes brain changes that are long-term, which is why people can recover from acute withdrawal symptoms within a week of quitting smoking, but they may crave a cigarette for months or even years after. How dangerous is nicotine? Despite decades of awareness campaigns warning that smoking leads to cancer, stroke and heart disease among other health problems, millions of people continue to smoke, resulting in more than 7 million tobacco-related deaths per year worldwide.
A study from England indicates that alcohol may increase the level of dopamine in the brain’s reward system up to 350%, but more research is needed to make this determination. Experts agree that alcohol is highly addictive and ranks high on the addictiveness list. Possibly because it is legal, alcohol addiction is widespread—more than 17 million American adults have an alcohol use disorder, and more than 3 million people die around the world every year as a result of harmful alcohol use. Popular as a relaxant (depressant), alcohol can cause the user to feel less inhibited and, thus, more comfortable in social settings. This effect, however, can lead to repeated use and larger doses, which can lead to addiction and health problems like alcohol poisoning, liver disease, heart disease, diabetes and cancer. Alcohol withdrawal is excruciating and sometimes deadly, which is why medically assisted detox is needed.
6. Meth (crystal meth, methamphetamines)
A “home-brewed” mixture, meth is made from combining industrial chemicals with amphetamines. When people smoke, snort or inject meth, it impacts the brain’s reward system quickly and dramatically, causing levels of the neurotransmitters dopamine and norepinephrine to spike an estimated 10 times higher than normal, resulting in a rush of adrenaline that makes the user more alert and energetic. The come-down from the drug is also dramatic, causing a drastic drop in energy and mood, making the user want more almost immediately. Meth is as destructive as it is addictive because repeated use can permanently damage the neurons, leading to a significant decrease in the natural neurotransmitter levels in a user’s system. This causes users to seek more meth in an effort to regain even normal mood and energy function.
This opioid acts like other opioids in many ways, but blocks the euphoria that most opioids produce when they activate the brain’s opioid receptors. For this reason, methadone (and its cousin, buprenorphine) is often used in medically assisted treatment (MAT) for opiate/opioid addiction. Methadone is used as a sort of replacement drug for heroin and other opiates to help the addicted person detox and recover. The unfortunate thing is that, even though methadone doesn’t cause euphoria, it is a highly addictive substance. This means that while methadone can be effective in keeping heroin addicts from relapsing and overdosing, some people become addicted. It’s important for the supervising addiction specialist to taper them off methadone gradually and monitor them closely.
Researchers estimate that roughly 20% of people who try cocaine become addicted to the stimulant, and though it now receives less media attention than it did in the past, cocaine remains a widely abused drug around the world with millions of people addicted. Like other highly addictive substances, cocaine stimulates sharp spikes in “feel-good” neurotransmitters in the brain’s reward center. With repeated use, cocaine causes natural production of these neurotransmitters to slow down. Once cocaine causes natural dopamine production to diminish, the user craves more of the drug to feel good again, leading to habitual use.
A group of synthetic psychoactive drugs that stimulate the central nervous system (CNS), amphetamines are prescribed (Adderall, Dexedrine) to treat narcolepsy, obesity and attention deficit/hyperactivity disorder (ADHD). They cause a spike in energy, alertness or excitability; their effect in the brain’s reward center gives many users a sense of pleasure, leading to their popularity as street drugs, where they are known as “uppers” or “speed.” These uppers are also popular as appetite suppressants or diet aids. Physical tolerance happens quickly, prompting users to take larger doses, which can lead to addiction and psychotic episodes. Withdrawal includes depression, anxiety and fatigue—symptoms so extreme they drive repeated use.
10. Benzos (benzodiazepines)
Benzodiazepines (Valium, Xanax and Klonopin) are usually prescribed to calm the nerves and the drugs do this by magnifying the effects of the brain’s GABA (Gamma-aminobutyric acid)—a natural calming chemical. Unfortunately, the body compensates by decreasing sensitivity in its GABA receptor cells, which can cause a person to become physically dependent on benzos to increase GABA’s effects—namely, anxiety reduction and a sense of calm. Ironically, some people trying to overcome other addictions will take benzos to manage the severe anxiety they experience as a withdrawal symptom, and soon become addicted to benzos instead. Withdrawal from benzos can also include panic attacks. Flunitrazepam (Rohypnol or “roofies”) is another benzo that is not approved as a prescription drug in the US, but is used illegally as a club drug or “date rape” drug. The drug is often taken with alcohol and causes a relaxed feeling that begins in about 15 minutes and can progress to difficulty with motor control and loss of consciousness (and memory of what happened while under the drug’s influence). The effects can last 4-5 hours.
11. GHB (Gamma-hydroxybutyrate)
A popular drug at nightclubs, parties and raves, GHB or “G” is a depressant that affects the central nervous system and GABA causing a relaxed feeling in users, who often mix it with alcohol to amplify their intoxication. Abused as a “date rape” drug, GHB’s interplay with alcohol is thought to cause the user to build up a tolerance to it, causing them to increase their dosage to feel its effects, resulting in addiction. The effects of GHB include euphoria and increased sex drive, but it can also lead to hallucinations, loss of consciousness, amnesia, coma and overdose—particularly when mixed with alcohol and other substances. Withdrawal symptoms can last several days and include anxiety, insomnia, delirium, nausea and vomiting, among others.
12. MDMA (methylenedioxymethamphetamine, known as Molly and Ecstasy)
As with other addictive substances on this list, the brain’s “feel good” neurotransmitters are impacted by Ecstasy, a synthetic psychoactive that is popular as a recreational drug—particularly among young adults. Its effects include euphoria, relaxation, heightened sensation and empathy, which drive repeated use. Research of Ecstasy’s properties are based primarily on animal studies, showing that as the drug causes surges of serotonin, dopamine and norepinephrine in the brain, it also damages the associated neurons, leading to rapid-onset physical tolerance and negative withdrawal symptoms as the drug leaves the system. Withdrawal symptoms include fatigue, inability to concentrate, appetite loss and depression. Even though experts can’t always agree on the exact criteria for assessing which drugs are most addictive, they appear to agree that addiction treatment programs are the safest and most effective way to overcome problems with these 12 highly addictive substances. Professional addiction treatment and rehabilitation, usually starting with medical detox, makes recovery possible. Sources: Experts Ranked the Top 5 Most Addictive Substances on Earth. Kelly Tatera. The Science Explorer: Brain and Body, March 2016. https://thescienceexplorer.com/brain-and-body/experts-ranked-top-5-most-addictive-substances-earth World Drug Report 2017: 29.5 million people globally suffer from drug use disorders, opioids the most harmful. United Nations Office on Drugs and Crime, June 2017. https://www.unodc.org/unodc/en/frontpage/2017/June/world-drug-report-2017_-29-5-million-people-globally-suffer-from-drug-use-disorders–opioids-the-most-harmful.html Cannabis, Coca & Poppy: Nature’s Addictive Plants; Production and Distribution. DEA, 2016. https://www.deamuseum.org/ccp/opium/production-distribution.html Tobacco Fact Sheet, World Health Organization (WHO), May 2017. https://www.who.int/mediacentre/factsheets/fs339/en/ How scientists rank drugs from most to least dangerous — and why the rankings are flawed. German Lopez. Vox, December, 2015. https://www.vox.com/2015/2/24/8094759/alcohol-marijuana Government drug adviser David Nutt sacked. Professor David Nutt asked to resign after his claims that ecstasy and LSD were less dangerous than alcohol. The Guardian, October 2009. https://www.theguardian.com/politics/2009/oct/30/drugs-adviser-david-nutt-sacked Development of a rational scale to assess the harm of drugs of potential misuse. D Nutt, et al. The Lancet, March 2007. https://www.sciencedirect.com/science/article/pii/S0140673607604644 These are the 10 most addictive drugs in the world. Kevin Loria, Skye Gould. Business Insider: Tech News, March, 2016. https://www.businessinsider.com/what-are-the-most-addictive-drugs-heroin-alcohol-2016-3