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Most addictive drugs affect the brain’s reward system. They trigger the brain to release dopamine, often in excessive amounts. Increased dopamine levels causes euphoria, which reinforces the user to repeat pleasurable but unhealthy behaviors like taking addictive drugs.
Why Do People Get Addicted to Drugs?
As a person continues taking drugs, the brain’s reward center adapts and becomes less responsive to their effects. When this happens, the user will feel less high than when they first started taking the drug. This is known as tolerance, and is a sign that a person has developed a dependence on the drug.
People with drug dependency experience withdrawal symptoms if they stop taking. This makes it difficult for them to stop their use of addictive substances.
An increased tolerance might make someone take more of the drug to achieve the same high and cause them to become less and less able to derive pleasure from other things they once enjoyed. An increased tolerance will also make someone experience unpleasant withdrawal symptoms when they don’t take the drug. At this point, people often use drugs or alcohol to keep from feeling bad rather than for their pleasurable effects.
Repeated use of drugs can also damage the essential decision-making center of the brain, known as the prefrontal cortex. When the frontal cortex isn’t working properly, people can’t decide to stop taking the drug—even when faced with severe consequences.
The inability to stop taking drugs is what eventually causes a person to become addicted to them. It is worth noting that while many drugs have addictive properties, some are more highly addictive than others.
7 Most Addictive Drugs in the World
Some of the most addictive drugs in the world include:
1. Prescription Opioids
Common Street Names: Captain Cody, Dillies, Schoolboy, Oxycat, Percs, White Stuff
Prescription opioids belong to the opioid class of drugs which are either derived from poppy plants or produced synthetically in a laboratory. Regardless of how it’s made, all opioids are chemically alike. They bind with opioid receptors to block nerve signals between the brain and the body. This gives them the ability to effectively block pain, which is why they’re often used to manage chronic pain.
Unfortunately, they also produce a “high” which makes them extremely addictive. What’s dangerous with opioids is that you can abuse them and not know it. Accidental addiction can happen with prescription opioids if a person:
- Takes more than the prescribed dose
- Takes it longer than prescribed
- Drinks them with alcohol without knowing the risk
When a person misuses opioids, they can develop tolerance to these drugs. Drug tolerance increases the risk for addiction and overdose.
In the United States, as much as 96.6% of people who misuse opioids (or 9.7 million Americans) use opioid painkillers.1 Globally, opioid use disorder (OUD) affects about 16 million people.2
List of Addictive Opioids
Below are some misused opioids:
Codeine is one of the most commonly prescribed addictive drugs. It is used to treat mild to moderate pain, especially when the person doesn’t respond to less potent painkillers such as ibuprofen and paracetamol.
Codeine is also used in cough and cold medications. It is either available as a single-ingredient product or in combination with acetaminophen or aspirin.
Hydrocodone is a semi-synthetic opioid that acts as an analgesic (pain reliever) and antitussive (cough suppressant). Hydrocodone can also produce feelings of euphoria, and is recognized as one of the most addictive drugs.
3. Oxycodone (Tylox®, Percodan®, and OxyContin®)
Oxycodone is a semi-synthetic opioid drug prescribed for pain. Some of its street names include Hillbilly Heroin, Kicker, OC, Ox, Roxy, Perc, and Oxy. Oxycodone produces feelings of relaxation and euphoria.
4. Meperidine (Demerol®)
Meperidine hydrochloride is a synthetic opioid used as an analgesic. This drug can treat moderate to severe pain.
Fentanyl is a synthetic opioid that is 50 to 100 times stronger than morphine. This makes it extremely potent, which explains why it is often used to manage severe pain in chronic conditions such as late stage cancer. Fentanyl is typically sold on illegal drug markets because its effects are like heroin.
Methadone is approved by the Food and Drug Administration (FDA) for the treatment of opioid use disorder (OUD) and other substance abuse problems, including people addicted to alcohol. It is a long-acting opioid agonist and a schedule II controlled medication.
When taken as prescribed, methadone is safe and effective. It is the drug of choice for medication-assisted treatment (MAT) and helps patients experience less severe withdrawal symptoms. Methadone prevents relapse during early recovery, so they can finally focus on reclaiming their lives.
Side Effects of Prescription Opioids
Common side effects of opioids include:
- Physical dependence
- Respiratory depression
Dangers of Prescription Opioids
Opioid abuse and addiction can lead to the following consequences:
- Delayed gastric emptying
- Immunologic and hormonal dysfunction
- Muscle rigidity
- Accidental overdose death
An average of 128 Americans die every day from an opioid overdose.
Common Street Names: H, Horse, Hero, Beast, Smack, Hell Dust, Skag, Junk, Snow
Heroin is an illicit opioid made from morphine. Heroin appears as a white or brown powder, or a black sticky substance known as black tar heroin. Heroin users inject, sniff, snort, or smoke this addictive substance. The National Survey on Drug Use and Health (NSDUH) recorded 745,000 heroin users in 2019.1
Side Effects of Heroin Drug Use
Below are the side effects of heroin use:
- A surge of pleasure or euphoria
- Dry mouth
- Warm flushing of the skin
- Heavy feeling in the arms and legs
- Nausea and vomiting
- Severe itching
- Clouded mental functioning
- Going “on the nod,” a back-and-forth state of being conscious and unconscious
Dangers of Heroin
Heroin use may cause the following health consequences with long-term use:
- Heroin addiction
- Higher likelihood of contracting HIV or other bloodborne diseases
- Collapsed veins
- Damaged tissue inside the nose
- Infection of the heart lining and valves
- Liver and kidney disease
- Lung complications, including pneumonia
- Mental illnesses such as depression and antisocial personality disorder
- Sexual dysfunction (for men)
- Irregular menstrual cycles (for women)
- Accidental overdose death
3. Cocaine and Crack Cocaine
Common Street Names: Coke, Blow, Crack, Rock, Snow, Flake, Line, Icing, Pearl, Snowcones, White Powder, and Dust
Cocaine is a stimulant drug made from the coca plant. It looks like a fine white powder or a crystallized rock. In the United States, there are about 5.5 million Americans suffering from cocaine use.1
Crack cocaine or “crack” is one of the most common ways this drug is prepared. Unlike cocaine, which is purely made of hydrochloride salt, crack cocaine is a combination drug that consists of cocaine, baking soda, and water. It produces instant but short-lived effects. Because they don’t last long, users tend to binge these drugs.
Both cocaine and crack are highly addictive drugs. However, studies show that you can easily become addicted to crack cocaine (if smoked) than pure cocaine (if snorted).3
Side Effects of Cocaine Use
People who use cocaine will experience the following symptoms:
- Extreme happiness and energy
- Mental alertness
- Hypersensitivity to light, sound, and touch
- Constricted blood vessels
- Dilated pupils
- Raised body temperature and blood pressure
- Fast or irregular heartbeat
- Tremors and muscle twitches
- Restlessness and insomnia
Dangers of Cocaine Abuse and Addiction
Cocaine use is associated with a myriad of health risks, such as:
- Loss of smell
- Problems with swallowing
- Respiratory distress
- Higher risk of lung infections like pneumonia
- Higher risk for contracting HIV, hepatitis C, and other bloodborne diseases (when injected)
- Higher likelihood of engaging in risky sexual behavior and contracting sexually transmitted disease
- Cardiac arrest and death
Alcohol belongs to a class of drugs called depressants. Depressants work by slowing the function of the body’s systems. Its main active component is ethyl alcohol or ethanol, which can be found in all alcoholic drinks (including wine, beer, and liquor).
Due to its easy accessibility, there are more people addicted to alcohol than all types of drugs combined. There are about 14.1 million American adults struggling with alcohol abuse and addiction, compared to just 7.4 million who use illicit drugs.1
Side Effects of Alcohol Use
Alcohol consumption can result in the following:
- Impaired judgment
- Slurred speech
- Vomiting and diarrhea
- Distorted vision and hearing
- Decreased coordination
- Short-term memory loss or blackouts
Dangers of Alcohol Abuse
Alcohol abuse increases the risk for several health consequences, including:
- Alcohol addiction
- Injuries or violence
- Alcohol poisoning
- More likely to engage in risky sexual behaviors, which can result in unintended pregnancy or becoming infected with sexually transmitted diseases, including HIV
- Higher risk of miscarriage, stillbirth, or fetal alcohol syndrome among pregnant women
- High blood pressure or heart disease
- Liver disease
- Digestive problems
- A weakened immune system
- Learning and memory problems
- Mental illness, including depression and anxiety
People with advanced alcohol use disorder may suffer from severe withdrawal symptoms called delirium tremens.
Nicotine is a powerful stimulant that speeds up the transmission of nerve impulses between the brain and body. It is the primary psychoactive ingredient found in products such as cigarettes, cigars, pipe tobacco, snuff, and chewing tobacco.
Nicotine is not only an addictive substance. Like alcohol, it’s also easily accessible. 14 in every 100 American adults smoked cigarettes in the United States, making nicotine as the most abused drug in the country.4
Side Effects of Nicotine Use
The following side effects may occur when using tobacco products that contain nicotine:
- Abdominal cramps
- Vomiting or weakness
- Increase in heart rate
- Increased ability to concentrate
- Temporary reduction in the urge to smoke
- Bad breath
- Tingling and numbness in fingers and toes
- Reduced appetite
Dangers of Nicotine
When a large amount of nicotine is taken, users may experience the following dangerous effects:
- Feeling faint
- Fast breathing
- Respiratory arrest and death
6. Stimulants (Uppers)
Stimulants or “uppers” are addictive substances that speed up the body’s systems. They are available as prescription drugs for the treatment of attention-deficit hyperactivity disorder (ADHD) and narcolepsy. But they’re also sold illegally on the streets as illicit drugs.
In general, stimulant drugs increase a person’s energy, focus, and attention while reducing the need for sleep. Prescription stimulants such as Adderall®, Concerta®, and Ritalin® are often abused by college students to help with tests and improve their overall school performance.5
With repeated use, stimulants can quickly lead to dependence. People who misuse them may experience withdrawal symptoms the moment they stop using.
List of Addictive Stimulants
1. Amphetamine, Dextroamphetamine (Adderall®)
Adderall® is a prescription drug that is used to treat ADHD. Adderall is also used illicitly as a study aid, to stay awake, and to suppress appetite.
2. Methylphenidate Hydrochloride (Concerta® and Ritalin®)
Concerta® and Ritalin® are schedule II drugs containing methylphenidate as their active ingredient. These stimulants help calm and stabilize nerve impulses in people with attention deficit hyperactivity disorder.
Ecstasy or MDMA contains 3,4-methylenedioxymethamphetamine (MDMA) as its main component. It is chemically similar to both stimulants and hallucinogens, producing feelings of increased energy, pleasure, emotional warmth, and distorted sensory and time perception.
Ecstasy is an illicit drug. People who use it usually take it as a capsule or tablet. Some swallow it in liquid form or snort the powder.
4. Meth and Crystal Meth
Meth or methamphetamine is a stimulant that speeds up the body's systems. It is medically prescribed as Desoxyn® for the treatment of obesity and ADHD.
Meth is also used as a recreational drug and is smoked, snorted, or injected. Street names for meth include Speed, Ice, Shards, Bikers Coffee, Stove Top, Tweak, Yaba, Trash, Chalk, Crystal, Crank, and Shabu. Ice or crystal meth is an extremely potent form of methamphetamine. It has a rock-like appearance, and is one of the most addictive drugs.
Dexedrine sulfate is a long- or short-acting drug that is taken orally. It is primarily used in the treatment of ADHD. But it can also be used to treat narcolepsy.
Like Adderall®, its main active component is a type of amphetamine. And while less potent, one can still become addicted to this drug if misused.
Side Effects of Stimulants
The common side effects of stimulant use include:
- Feelings of euphoria
- Increased heart rate and blood pressure
- Increased alertness
- Increased talkativeness
- Reduced appetite
Dangers of Abuse and Addiction to Stimulants
Consuming high doses of stimulants or taking them for purposes other than intended, lead to the following dangers:
- Increased body temperature
7. Barbiturates or Benzodiazepines (Downers)
Barbiturates or benzodiazepines are used to decrease activity in the central nervous system (CNS). These “downers” are generally used to treat severe cases of insomnia. But they can also control seizures or be used as an adjunct to anesthesia.
People misuse barbiturates for several reasons, including:
- To help with sleep
- Reduce anxiety and inhibitions (e.g., cravings and impulsive behavior)
- Treatment of unwanted effects produced by illicit drugs
In 2018, the Substance Abuse and Mental Health Services Administration (SAMHSA) reported that as many as 405,000 Americans aged 12 and above use barbiturates.6
List of Addictive Barbiturates
1. Alprazolam (Xanax®)
Xanax® is used to treat anxiety and panic disorders.
2. Valium (Diazepam®)
Valium is used in the treatment of anxiety, muscle spasms, seizures, and alcohol withdrawal symptoms. It can also be prescribed as a sedative before surgery.
3. Klonopin (Clonazepam®)
Klonopin is used to treat the symptoms of seizures, epilepsy, and panic disorder.
4. Ativan (Lorazepam®)
Ativan is used to treat anxiety disorders. Like many prescription drugs, people who use them don’t realize they’ve developed drug dependence until it’s too late.
Librium is used to treat symptoms of anxiety. It is often prescribed to reduce fear and anxiety before surgery.
“Sleeping pills” are formulated to help people get good quality sleep. They are either available on prescription or sold as over-the-counter medicines. Sleeping pills belong to a class of drugs called hypnotics and are known for their sedative properties. If abused, they can cause dependence and serious side effects.
Phenazepam is a benzodiazepine drug that is used to treat some types of mental illness. It is five times stronger than valium, which explains why phenazepam produces concerning side effects. Some of which include loss of coordination, extreme drowsiness, and amnesia.
Side Effects of Barbiturates
Barbiturate use can result in these side effects:
- Relief of anxiety
- Low blood pressure (hypotension)
- Skin rash
- Lack of inhibition
- Impairment of memory, judgment, and coordination
Dangers of Abuse and Addiction to Barbiturates
Long-term exposure to barbiturates can lead to various complications, such as:
- Abnormally slow breathing or breathing cessation
- Liver injury
- Megaloblastic anemia
- Stevens-Johnson syndrome
- Paranoia and suicidal thought
Symptoms of Substance Use Disorder (SUD)
Symptoms of substance use disorder (SUD) include one or more of the following symptoms within 12 months:
- Recurring substance use where the user is either unable to or has the reduced capacity to fulfill their obligations at work, school, or home as a result of alcohol and other addictive drugs
- Continued use of an addictive substance in places or situations that are inappropriate or physically dangerous (e.g., driving, at work or school, while using heavy machinery)
- Getting into legal problems due to substance use
- Using addictive drugs despite having social or interpersonal problems that are either caused or made worse by their effects
The more addictive a drug or substance is, the more potent its effects. With continued use, they can quickly lead to the development of drug dependence, drug abuse, and drug addiction.
The most addictive drugs — which include crack cocaine, crystal meth, and prescription opioids — are also accompanied by severe withdrawal symptoms that make it difficult to quit.
If you or a loved one is addicted to one or several of these substances, seek medical help right away. Starting addiction treatment early helps ensure a safe and long-lasting recovery.
Addiction Treatment Options
Drug addiction treatment options include inpatient, outpatient, partial hospitalization, or detox programs. Drug addiction therapies can consist of medications, behavioral therapies, or their combination. The right treatment program depends on the patient’s individual needs and on the types of drugs they use.