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Most Addictive Drugs: The World's Deadliest Substances

The World’s Most Addictive Drugs

With so many substances available, including both illegal and prescription drugs, it can be difficult to know which ones pose the greatest risk for addiction. 

Fortunately, an answer does exist.

In 2007, scientists and researchers conducted a study that rated 20 different substances, using multiple criteria, to determine which were most likely to result in addiction or dependence. A person’s odds of developing both physical dependence and psychological dependence were taken into account, along with the intensity of the pleasurable sensation the drug provided and the intensity of the unpleasant symptoms experienced during withdrawal.

By conducting this study, the researchers were able to identify the most addictive drugs and grade them using a clear, quantifiable measurement system.

Let’s take a closer look at some of the substances that were included in the study and the severity of their effects.

Opioids (Highly Addictive)

Opioids, including heroin, fentanyl, oxycodone, and morphine ranked the highest in terms of being addictive. Of all of these, heroin is considered to be the most addictive drug in the world. These substances produce profound feelings of euphoria, calmness, and pain reduction. Unfortunately, however, the body develops a tolerance to these substances the more frequently they are used, which results in the individual requiring higher and higher doses in order to achieve the same effect. Opioids also produce severe withdrawal symptoms, including diarrhea, abdominal cramps, vomiting, seizures, high blood pressure, fever, hallucinations, and in extreme cases, even death. For this reason, opiates considered the most addictive substances of all.

Opiate Drug Tests

Cocaine (Highly Addictive)

Cocaine was ranked the second most addictive drug in the study. It produced feelings of extreme pleasure amongst users that were similar to opiates in terms of intensity. It differed from opiates, however, with regards to physical and psychological dependency. Psychologically, heroin (an opiate) remained the most addictive drug, with cocaine coming ranking marginally lower. And in terms of physical addiction, cocaine was only half as addictive as opiates. It’s important to note, however, that 17 percent of people who try cocaine develop an addiction. Additionally, a 2006 study showed that 35.3 Americans aged 12 and older have tried cocaine and 8.6 million have tried crack, which has an ever higher addiction rate.

Cocaine Drug Tests


Amphetamines (Highly Addictive)

When most people think of amphetamines, they think of methamphetamine (otherwise known as crystal meth). And while crystal meth is certainly one of the most addictive amphetamines in the world, there are also prescribed versions of amphetamines, including Adderall, Ritalin, and Dexedrine, which can also be addictive. These drugs are sometimes categorized as “uppers”, since they have a stimulating, energizing effect. Crystal meth, specifically, is often smoked or injected, and has an extremely high rate of addiction. It also produces severe withdrawal symptoms, including paranoia, itching, depression, muscle pain and insomnia. 

Amphetamine Drug Tests


Nicotine (Highly Addictive)

Many people are surprised to learn that nicotine ranks just slightly below cocaine in terms of psychological addictiveness. This shows that attempting to quit smoking can have powerful cognitive effects. This is likely due to the fact that nicotine alters brain chemistry and has a noticeable impact on emotions. Nicotine has been shown to increase mood and concentration, as well as decrease sensations of anxiety and irritability, which are prominent factors in what makes it one of the most addicting drugs. When those with nicotine addiction attempt to quit, the body and mind must adjust to no longer being able to depend on these effects— a process that can cause sweating, nausea, headaches, and intense cravings.

Nicotine Drug Tests


Barbiturates (Highly Addictive)

Barbiturates are some of the most addictive drugs that are prescribed medically. They are known for producing a calming, sedative effect. Some of the most commonly known barbiturates include Amytal, Nembutal, and Seconal. They are typically prescribed to treat seizure disorder, migraine headaches, insomnia and severe forms of anxiety. While their pleasurable effects are considered less powerful than those of opiates or cocaine, they do have a relaxing effect that can make users calm, less stressed, and drowsy. If misused, however, dependency can develop. When abused and consumed in higher doses, side effects include slurred speech, unsteadiness, erratic behavior, and extreme sleepiness. 

Barbiturates Drug Tests


Alcohol (Moderately Addictive)

When trying to determine the most addicting drug in the world, alcohol is rarely top of mind. And while alcohol is not nearly as physically or psychologically addictive as opiates or cocaine, it does still pose a serious risk. Firstly, alcohol is among the most commonly abused substances in the world, and studies show that one in every 13 Americans struggles with alcohol dependence. Secondly, alcohol produces some of the most dangerous withdrawal symptoms of any substance on this list, including grand mal seizures, stroke, and in extreme cases, even death. For these reasons, alcohol remains one of the most addictive substances on the market today.

Alcohol Tests


Benzodiazepines (Moderately Addictive)

Benzodiazepines are a class of prescription drugs that have a calming effect. They are also known for their fast absorption time, which means their positive effects are felt in as little as 30 minutes after ingestion. While the relaxing, mood-boosting impact of benzodiazepines are enough for a person to become dependent on, they aren’t considered as powerful as those associated with opiates or barbiturates. Additionally, their withdrawal symptoms are often less severe than other drugs on this list, contributing to their lower ranking. With that being said, 13 percent of Americans report having used benzos in the last year, and one in five users have misused the drug. So while it isn’t high on the list of most addictive drugs, benzo abuse is still very much a concern.

BZO Drug Tests


Marijuana (Mildly Addictive)

Marijuana, also known as pot or weed, ranks low on the list of most addictive drugs since it has not been proven to produce a physical dependence. That does not mean, however, that users can not become dependent on using marijuana. Many regular smokers develop a psychological dependence and experience changes in mood, energy, and their ability to focus when they stop using the drug entirely. While there are no major or life-threatening withdrawal symptoms associated with ceasing marijuana use, some chronic users do report instances of depression, trouble sleeping, and irritability when they reduce their usage suddenly.

Marijuana Drug Tests

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