Drug addiction continues to plague the United States and beyond, and certain drugs have reached epidemic proportions in the U.S. Not everyone who tries a drug once will develop an addiction, although they are playing with fire if they decide to experiment with one of the substances on the list below. A individual’s genetic makeup, social surroundings, family structure and even personal income play a role in his or her chances of developing a drug addiction.

#10 Marijuana

Although marijuana is the most benign drug on this list, it certainly can cause changes in the brain to the point of addiction. As the most commonly used illicit substance, marijuana is now legal in some states in the U.S., and it’s available in many others via prescription. Marijuana use disorders are often associated with dependence—in which a person feels withdrawal symptoms when not taking the drug. Marijuana dependence occurs when the brain adapts to large amounts of the drug by reducing production of and sensitivity to its own endocannabinoid neurotransmitters.

#9 Ecstasy

Ecstasy, or the “love drug” was commonly used in the 1980s and is still part of the club scene. Users feel happy, loving, alert and focused, yet very relaxed when under its influence. Some users can also do without sleep for between 24-72 hours at a time. Ecstasy’s active ingredient is MDMA, which is now popular in its pure form, known as “Molly.” Ecstasy and Molly and are commonly available as a capsule, tablet or powder. Ecstasy’s side effects include muscle cramps, blurred vision, increased heart rate, nausea, chills and hallucinations. MDMA-related deaths do happen occasionally, but they rarely follow an overdose on ecstasy.

#8 Benzodiazepines

“Downers” like Xanax, Valium and Klonopin make users feel calm and relaxed by increasing the brain’s nerve-calming agent. It’s hard to get off this drug once a tolerance starts to build up, which can take place very quickly. More than 15 types of benzodiazepines, aka “benzos,” are available via prescription, although forms of the substance are traded on the black market as well. Long-term use of benzos can cause brain damage, and withdrawal symptoms include body aches, muscle stiffness, sleep disturbance, anxiety, seizures, irritability and memory problems. There were approximately 10,000 deaths because of benzodiazepine overdose in the U.S. in 2017.

#7 Methadone

Methadone is an opioid that is commonly prescribed to treat heroin or morphine addicts, as this pain reliever helps the user come down from those harder substances. Even though the risk of addiction is low when used as directed by a doctor in a clinical setting, many recreational users have been drawn to the substance and subsequently become addicted. Methadone generally comes in the form of tablets, powder and liquid. It shares some of the same effects as morphine, but is not quite as strong or addictive as that opiate. U.S. government statistics show that, as of 2015, methadone is the fastest-growing cause of narcotic-related deaths, possibly since it’s far less expensive than other prescription painkillers.

#6 Amphetamines

Not to be confused with methamphetamine, amphetamines (or “uppers”) create a rapid tolerance and intense cravings in users. They make users feel confident, energetic and euphoric, and they may be attractive for their appetite-curbing traits. This substance is featured in some legal drugs such as Adderall and Dexedrine, although several street forms are also available. Amphetamine is a highly addictive substance. Because of the way it acts on the body, this drug can cause changes in the way the brain behaves. In particular, amphetamine and related substances can significantly alter the brain’s pleasure response, destroying pleasure receptors in the brain and decreasing the ability for the body to feel pleasure without using the drug.

#5 Cocaine

Cocaine is a white powdery substance that reacts with the body’s central nervous system, producing energy and euphoria. It is most commonly snorted, but can also be smoked (also known as “freebasing”) or dissolved in water and injected. Cocaine is also referred to as coke, blow or powder. Although most people today recognize that cocaine is addictive, thousands are still drawn to it. Once someone becomes addicted to cocaine, it can be very hard to stop. This is because cocaine abnormally increases the level of dopamine in the brain, eventually reprogramming the brain reward system.

#4 Bath Salts

Bath salts are a synthetic drug that create a feeling of euphoria and are taken by injecting, snorting or smoking the substance. Bath salts are considered a cheap alternative to cocaine, ecstasy or methamphetamine. Bath salts are about 10 times more powerful than cocaine, increasing the potential for overdoses leading to death, even one dose can cause seizures and death. While bath salts use appears to have declined recently, many sellers have relabeled these products as “molly” or “flakka”, so many users don’t even realize they’re taking bath salts.

#3 Methamphetamine

Methamphetamine affects the dopamine and norepinephrine levels in the brain, making the user alert and hyperactive. Meth releases massive amounts of dopamine into the brain and suppresses norepinephrine production. Users develop a tolerance quickly and develop cravings for more of the substance. Methamphetamine can be smoked, snorted or taken orally. It can also be dissolved in water or alcohol and then injected. Illicitly manufactured methamphetamine is available on the street with an appearance resembling translucent white or blue, shattered shards of glass. Although similar, if not identical in chemical composition, this form is frequently called crystal meth.

#2 Heroin

Heroin users instantly get a “rush,” and after a time, cannot experience any good feelings without using it. Addicts get intense cravings while going through withdrawal. Heroin is a semi-synthetic substance that is extracted from the opium plant, making it a member of the opioid class of drugs. Heroin is generally taken via needle injection, although pure forms of the drug can be smoked or snorted. In 2013, more than 8,000 Americans died from a heroin-related overdose.

#1 Crack Cocaine

Crack cocaine is a hard, mineral-like substance with an off-white tint. Crack is made by mixing baking soda or ammonia into the powder form of cocaine. This mixture is then heated with a lighter or torch until it heats into the the “rocks” known as crack cocaine. It is most often vaporized in a glass pipe and inhaled, though some people use soda cans or aluminum foil to heat it. Many users also inject crack. It causes the user’s brain to release large amounts of dopamine, which results in intense feelings of pleasure and a burst of energy for about 10 minutes. Some users become addicted to crack the first time they try it. Due to its potency, there is a high risk of fatal overdose from using crack cocaine. Even someone using the drug for the first time can overdose.