Marijuana is currently one of the most popular intoxicating substances in the United States. While the Drug Enforcement Administration (DEA) classifies the drug as a Schedule I substance – meaning there is no medical benefit and it is considered dangerous to health – individual states across the country are adopting laws that legalize the growing, processing, distribution/sale, and consumption of marijuana. As of 2017, 26 states and the District of Columbia have legalized some level of marijuana use, typically for medical reasons; however, the recreational marijuana movement is becoming popular too, with seven states and DC legalizing recreational sale and use of the drug.

Arguments in favor of recreational use of marijuana claim that it is no more harmful than alcohol or cigarettes, and that in moderation, it does not harm the body or brain. Studies, however, show that marijuana can have many negative impacts on a person, especially when used consistently. It may be true that marijuana is no more harmful than other legal drugs, including tobacco and alcohol, but these drugs are also dangerous, addictive, and can cause long-term health problems. It is important to consider the risks of using marijuana, including increased risk of some mental health disorders, cancer, infectious disease, and addiction.

One of the most hotly debated topics around marijuana, as policy and cultural attitudes toward the substance change, is whether or not marijuana is a “gateway drug,” leading to other addictions. Certainly, abusing marijuana and other drugs at the same time is prevalent among people who struggle with substance abuse, but does marijuana use cause a person to try, and become addicted, to other drugs?

Is Marijuana Really a Gateway Drug?

What Is Marijuana?

What Is Marijuana?

Before discussing marijuana as a gateway to addiction to other drugs, it helps to understand what marijuana is. The plant Cannabis sativa has been bred into multiple strains; the flowers, leaves, stems, and seeds are all harvested from this plant and dried. The dried plant matter is marijuana, a drug that contains over 400 chemicals, two of which are the primary focus of most marijuana agriculture.

THC, or delta-9-tetrahydrocannabinol, is the psychoactive, intoxicating chemical; CBD, or cannabidiol, is a secondary chemical believed to be effective in relieving pain, relaxing the body, and easing brain chemistry to reduce the risk of seizure disorders, anxiety, panic attacks, and other disorders. CBD oil is one of the main products in states that tightly regulate medical marijuana, used to treat several seizure disorders, ease chronic pain in long-term illnesses, and improve appetite and mental health in people with cancer.

People who seek out marijuana for recreational reasons, though, aim for strains with higher THC content. According to the National Institute on Drug Abuse (NIDA), 11 million young adults between the ages of 18 and 25 tried marijuana at least once in 2015. However, after several years on the rise, rates of marijuana abuse among middle and high school students began to drop in 2015; at the same time, adolescents and young adults are much more likely to believe that marijuana is harmless.

In reality, marijuana is far from harmless. Consistent use of the drug can cause chronic health problems and changes to brain chemistry can cause alterations in the structure of the brain itself. This is especially likely to occur in adolescents and young adults who abuse marijuana before their brains have matured. Long-term health consequences associated with marijuana abuse include:

  • Reduced cognitive ability
  • Impaired memory and memory loss
  • Learning difficulties
  • Increased risk of mental health problems, including anxiety, depression, and schizophrenia, in people who are predisposed to these issues
  • Breathing problems
  • Increased risk of many types of cancer
  • Increased heart rate, leading to cardiovascular harm
  • Increased risk of birth defects in babies when used by pregnant women
  • Increased risk of infectious disease due to lowered immune system function
  • Gum disease
  • Sexual dysfunction

People who drive within three hours of ingesting marijuana in any form are more likely to cause a serious car accident due to intoxication. About 9 percent of adults who use marijuana will become addicted to the drug while 17 percent of teenagers who use marijuana will become addicted. Although these numbers seem small, with millions of people all over the US using the drug and thinking it is safe, the risk of an epidemic of addiction increases. One in three people in America tries marijuana, so there is a risk of thousands of people struggling with addiction.

But, is marijuana a gateway drug to other kinds of addiction and substance abuse? Scientific research is torn on this topic. The general concept is that “softer” drugs like alcohol, tobacco, and marijuana act as gateways to harder substances, often heroin or cocaine. The hierarchy as originally described begins with occasional alcohol or tobacco use, typically at a young age; this leads to marijuana; and marijuana abuse leads to heroin, meth, cocaine, and other drugs. While the combination of these substances has been reported among people who currently struggle with addiction to potent drugs like heroin and crack, the succession may not be causally linked.

The Arguments for Marijuana as a Gateway Drug

Animal studies suggest that previous marijuana use enhances the pleasure associated with intoxication on other substances, including tobacco – a phenomenon referred to as cross-sensitization. Addiction to marijuana and addiction to other drugs are often found together, suggesting a pattern of polysubstance abuse. People who now struggle with addiction to potent drugs like crack cocaine, crystal meth, and heroin typically abused marijuana first. It is rare for people to self-report struggling with heroin addiction, for example, before trying marijuana. However, these reports suggest that substance abuse likely began with the most available substances, which are typically marijuana, cigarettes, and alcohol, then moved on to more intense drugs as patterns of addiction set in. There is an association among these drugs, but this may suggest more specific rates of polydrug abuse rather than a linear pathway from one drug to another.

The Arguments for Marijuana as a Gateway Drug

Sociological studies suggest that, for some adolescents and young adults, marijuana acts as a gateway drug when the individual is in a specific environment. Young people struggling with psychological stress, who are poor, and/or those who are unemployed, are more likely to struggle with addiction of all kinds, whether it is to a prescription opioid, alcohol, or marijuana. Abusing intoxicating substances when these specific stressors are in place increases the risk of the individual developing an addiction because they experience temporary relief from these conditions.

A 2012 study conducted by Yale University suggested that young women, ages 18-25, were more likely to begin abusing prescription drugs if they previously abused marijuana. Prescription drug abuse, especially of opioid painkillers, is a serious epidemic in the US; understanding what situations increase the risk of developing this condition can help to prevent people from becoming addicted to prescriptions.

The Yale research team examined data from 2006, 2007, and 2008 collected and published under the National Survey on Drug Use and Health (NSDUH). The total sample size was 55,215 young adults; about 12 percent, or 6,496 people, reported struggling with prescription drug abuse. Among those 12 percent, about 57 percent reported abusing alcohol, 56 percent reported cigarette smoking, and 34 percent reported marijuana abuse. Among the men and women in the study, those with any history of marijuana abuse were 2.5 times more likely to try prescription drugs for nonmedical reasons. While women who used marijuana were more likely to try and/or develop an addiction to prescription drugs, including opioids,

men who used tobacco or alcohol were 25 times more likely to try narcotic painkillers for nonmedical reasons later.

Women did not have the same inclination if they only used alcohol and tobacco. This reinforces the idea that gateway drugs, including marijuana, are somewhat causally linked to stronger, more dangerous drug use later in life.

Those who begin abusing marijuana, alcohol, and/or tobacco in their teenage years are more likely to develop addictions to heroin, meth, and cocaine later in life and to continue to use their original substances of abuse at the same time. Polydrug abuse is even more dangerous, as it increases the risk of overdose and death. People who abuse marijuana are three times more likely to later abuse heroin, according to the Centers for Disease Control and Prevention (CDC). However, it should be noted that people who abuse prescription painkillers like Percocet or Vicodin are 40 times more likely to become addicted to heroin.

The Center for Addiction and Substance Abuse (CASA) at Columbia University found that adolescents between ages 12 and 17 who began abusing marijuana, alcohol, and tobacco were 266 times more likely to develop an addiction to cocaine, and adults who abused gateway drugs were 323 times more likely to also develop an addiction to cocaine. This study compared risks to those who did not abuse gateway drugs at all before trying other substances. Almost 90 percent of those who had ever tried cocaine, even once, used all three gateway drugs first.

The Arguments against Marijuana as a Gateway Drug

Outside of the discussed hierarchy – tobacco and alcohol lead to marijuana, which leads to harder substances – scientists who investigate the links between these drugs typically find that marijuana, specifically, does not lead directly to harder substance abuse. Instead, studies suggest that early abuse of all three gateway drugs – and usually, alcohol more often than marijuana – leads to later polydrug abuse and addiction.

The idea that marijuana is a gateway drug is tied to an assumption, from decades ago, that opioid abuse and marijuana abuse were tied together. In the 1950s, as marijuana abuse began to reach pop culture and a younger generation, the assumed link between heroin and marijuana led the public to fear a rise in heroin addiction associated with “beatniks” and “hippies” using marijuana more often. While these two drugs may have been correlated at one time in history, they are not causally linked. Former United States Attorney General Loretta Lynch stated, in 2016, that there was no evidence that legalizing marijuana would lead to further development of the current opioid epidemic.

The Arguments against Marijuana as a Gateway Drug

Typically, people who abuse marijuana do not move on to harder drugs, even if they ingest other substances while they also ingest marijuana. The confusion appears to be around people who are more susceptible to polydrug abuse and who are therefore more likely to ingest intoxicating substances when they are presented.

Additionally, socioeconomic factors and mental illness are better predictors of addiction to cocaine, heroin, meth, and other hard drugs compared to alleged gateway drugs. For example:

  • People who struggle with unemployment, low income, and poor environments are more likely to struggle with substance abuse of any kind, especially harder drug abuse.
  • People with friends who struggle with substance abuse are more likely to also struggle with substance abuse.
  • Mental health issues like bipolar disorder, schizophrenia, and antisocial personality disorder are more likely to lead to substance abuse (co-occurring disorders).

Still, gateway drugs are more widely available; alcohol and tobacco are legal for those over a certain age in the US, and marijuana is easily accessible across the country, even in states that have not passed any form of legalized use. People who have a genetic or environmental predisposition toward substance abuse are more likely to start with these drugs since they are easy to acquire; this may then later be correlated to moving to harder drugs, like heroin, meth, and cocaine, but the correlation stems from the cause of the environment or genetics.

Because marijuana is an intoxicating and addictive substance, whether the person taking this drug moves to harder drugs or not, they can still struggle with addiction and health problems associated with substance abuse. It is important to get help to end marijuana addiction even if this is the sole addiction a person struggles with.