It’s estimated that around 10% of U.S. adults struggle with drug addiction within their lifetime, but only 25% of these people ever receive treatment. Addiction is a disease that develops for a variety of reasons, such as through substance misuse, mental health conditions, genetics, environmental factors and more.

The Most Addictive Types of Drugs

Addiction can be physical, psychological or both. Drugs like alcohol, cocaine and opioids (including heroin and fentanyl) cause both forms of addiction and can lead to uncomfortable and even life-threatening withdrawal symptoms when use is suddenly stopped. Though marijuana is a common drug of misuse, its use typically only leads to psychological addiction.

Alcohol, cocaine and opioids are among the most commonly misused drugs. These substances directly trigger the reward centers of the brain, causing overwhelming feelings of pleasure. A person may want to use more of the drug in order to feel these same pleasurable side effects. However, the brain can quickly become dependent on these drugs, which compels a person to continue using them in order to avoid withdrawal symptoms.

Side effects, rates of use and descriptions of the most addictive drugs are as follows:

Alcohol

Alcohol is a central nervous system depressant, meaning it slows down brain activity. This leads to feelings of relaxation and can alter a person’s mood. Long-term alcohol use or binge drinking can lead to alcohol dependence and addiction. In 2018, 51.1% of people aged 12 or older reported using alcohol within the last month.

When someone uses alcohol, they may experience:

• Feelings of pleasure or relaxation
• Lower alertness
• Reduced judgment
• Exaggerated behavior
• Poor coordination
• Slurred speech
• Nausea or vomiting
• Difficulties with memory

Opioids

Prescription opioid painkillers include drugs like oxycodone and hydrocodone. Opioid painkillers are often misused for their euphoric effects, but these drugs are incredibly addictive due to their rapid effects on opioid receptors in the body. Using opioids, even as prescribed, can lead to dependence and addiction. In 2018, 1% of people aged 12 or older reported using pain relievers within the last month.

Side effects of prescription opioid painkillers include:

• Drowsiness
• Euphoria
• Slowed breathing
• Constipation
• Nausea and vomiting

Heroin

Heroin is an illicit opioid drug that creates effects similar to opioid painkillers. Heroin is often cheaper to buy and easier to find than prescription painkillers. The drug is incredibly dangerous due to its highly addictive nature and the potential for it to be mixed with other, stronger drugs like fentanyl. In 2018, 0.1% of people aged 12 or older reported using heroin within the last month.

The side effects of heroin include:

• Euphoria
• Dry mouth
• Itching
• Slowed breathing and heart rate
• Nausea and vomiting
• Constipation

Fentanyl

Fentanyl is a powerful opioid drug that is 50–100 times more potent than morphine. The drug is one of the largest contributors to the nationwide opioid epidemic, and 59% of opioid-related deaths in 2017 were caused by fentanyl. While fentanyl is sometimes prescribed by doctors for pain relief, it is often illegally manufactured and sold alone or mixed with other substances.

Side effects of fentanyl include:

• Euphoria
• Drowsiness
• Nausea
• Constipation
• Confusion
• Breathing problems
• Unconsciousness

Cocaine

Cocaine is a highly addictive stimulant drug that is sometimes mixed with opioids to create an intense high. In 2018, 0.7% of people aged 12 or older reported using cocaine within the last month, and 0.2% reported using crack cocaine.

The most common side effects of cocaine include:

• Increased heart rate, blood pressure, and body temperature
• Headache
• Abdominal pain
• Nausea
• Increased energy and alertness
• Insomnia
• Anxiety
• Erratic, violent behavior
• Psychosis

What Is Addiction?

Addiction is defined as drug use that is difficult to control despite negative consequences. Using drugs can lead to changes in the brain that affect a person’s behavior and self-control. People who try to quit using drugs often relapse due to the powerful cravings they feel, as well as the uncomfortable withdrawal symptoms that often come with addiction.

Addiction is devastating because it often comes to rule a person’s life. Someone struggling with addiction will have a difficult time keeping up with daily responsibilities at home, work and school, and they will need to use more and more of the drug in order to experience the same effects. Long-term drug use can easily lead to negative health consequences and increased risks of overdose.

Causes and Risk Factors

There are a variety of factors that make addiction more likely to occur. These include:

• Genetics: Genetics account for about half of a person’s risk of addiction. Additionally, mental health disorders play a large role in the development of addiction — many people use drugs in an attempt to self-medicate
• Environment: Factors like peer pressure, the environment at home, trauma, stress and parental guidance each play a role in addiction
• Development: The earlier someone uses drugs, the more likely they are to develop an addiction. Teens are more likely to engage in risky behaviors because their brains are still developing, which makes them more prone to taking drugs

Overdose Risks

An overdose occurs when someone takes too much of a drug, leading to potentially life-threatening side effects. The risks of an overdose increase exponentially when taking multiple drugs at the same time, as combining drugs can often cause the effects to multiply. For example, drinking alcohol and using opioids can cause respiratory depression, coma, and death.

Common signs of an overdose include:

• Slowed or stopped breathing or heartbeat
• Limpness
• Vomiting or gurgling noises
• Pale, clammy skin
• Blue or purple lips and fingernails
• Inability to be woken up

What Are the Signs of Addiction?

The most common signs of drug addiction include:

• The compulsion to seek out and use drugs despite negative consequences
• Intense urges for drugs
• Needing to use more of a drug to feel the same effects
• Experiencing withdrawal symptoms when ending drug use
• Driving or doing other risky behaviors while impaired
• Failing to meet responsibilities at work, home and school

Some signs can also be seen in a person’s behavior and appearance, such as:

• Lack of energy and motivation
• Weight changes
• Changes in friend groups
• Poor hygiene and grooming habits
• Missing work or school
• Financial issues