The Negative Effects of Marijuana


Marijuana advocates highlight the medical benefits of marijuana and how the substance is unlike other addictive drugs. Some studies support these claims, however, there are also studies that found potential negative effects of marijuana consumption. Understanding and acknowledging these potential negative effects are necessary for assessing whether marijuana should be a legal or illegal drug. The notable negative effects of marijuana relate to brain development, intelligence, mental illnesses, pregnancy, substance abuse, physical health, marijuana-related crimes, personal relations, and effects of second-hand marijuana smoke.

Short-Term Effects of Marijuana

The most obvious negative effects of marijuana are the short-term effects that come from the ‘high” feeling. These effects include short-term executive function impairment, such as issues with focus, attention, memory, and planning (Weir, 2015). Headaches, dizziness, and lightheadedness are also common short-term effects that last as long as an individual is experiencing the “high” from marijuana consumption. Since these effects are temporary, they may not pose serious threats to an individual’s health. However, this can vary depending on an individual’s overall health condition. Short-term effects may turn into long-term issues if an individual has an underlying health condition.

Marijuana use can also result in hallucinations, making an individual dangerous to himself and others. According to the Centers for Disease Control and Prevention (CDC), marijuana use can cause temporary psychosis and the development of anxiety, paranoia, and unpleasant thoughts. These effects can lead an individual to make wrong decisions and even harm others. For instance, an individual experiencing hallucinations may perceive a family member as someone who is trying to harm them, they may then attempt to fight back and accidentally hurt their family member. The development of unpleasant thoughts and anxiety may even lead to self-harm and even suicide.

Effects on Brain Development

Marijuana can have detrimental effects on brain development , especially on children and adolescents. Some studies showed how marijuana leads to damage to white and grey brain matter, as well as faster thinning of the prefrontal cortex (Weir, 2015; Schmidt, 2021). The damage to brain matter can negatively affect an individual’s impulse control and addiction-related process. This increases the risk of substance abuse as well as other brain function impairment. Additionally, faster thinning of the prefrontal cortex can lead to long-term behavioral and memory problems for users. This is most significant in a developing brain since faster thinning may result in unhealthy brain regions.

Loss of IQ Points

Along with marijuana’s effect on the brain, it can cause the loss of IQ points. Multiple studies concluded that marijuana use, especially beginning at a young age, can cause the loss of six to eight IQ points (cited in NIDA, 2021). However, some studies report a contrast to this conclusion, indicating that other factors may be causing the loss. Still, this potential relationship between marijuana and loss of IQ points is a topic of interest since, if true, it can have detrimental societal effects. While a loss of six or eight IQ points may seem low, it is enough to turn an average IQ score into below average. Additionally, since the  legalization of marijuana  has led to increased use of the substance, this can lower the IQ score of a significant percentage of the population.

Worsen Mental Illness Symptoms

The medical benefit of marijuana is one of the main arguments for its legalization. Despite many studies suggesting that marijuana is medically beneficial, some studies suggest that marijuana use can worsen the symptoms of mental illnesses. For instance, studies show that marijuana abuse can worsen PTSD symptoms and  increase substance use disorder for eating disorder patients (American Addiction Center, 2022; Ganson et al., 2021). High dosage and abuse of marijuana tend to result in these negative effects. However, most researchers agree that there is still a need for more clinical studies on marijuana to assess its effects on mental illness.

Danger to Pregnancy

Similar to alcohol, cigarettes, and other addictive substances, marijuana can have detrimental effects on pregnancy. According to the Substance Abuse and Mental Health Services Administration (SAMHSA), a mother using marijuana can pass the chemicals from the substance to the baby. This can cause issues with fetal growth that can lead to birth defects and stillbirth. After birth, children can develop problems with their executive functions. Studies have shown that 20% of pregnant women under the age of 24 use marijuana, indicating that the substance’s danger to pregnancy is a significant issue (NIDA, 2019). The legalization has normalized marijuana use to the extent that pregnant women are even using it while carrying a child.

Aside from the negative effects on birth, using marijuana while pregnant or while breastfeeding can risk putting negative effects of marijuana on the child. THC can excrete from the mother’s body into the breast milk, and then into the child (NIDA, 2019). Since children’s bodies and brains are developing, the negative effects of marijuana can be more severe. It can disrupt their brain development, impair their learning abilities, and change the structure of their brain.

Negative Physical Effects

While most negative physical effects of marijuana are short-term effects, there are instances that individuals can develop health problems due to marijuana use. One of these is the development of Cannabinoid Hyperemesis Syndrome, a disorder that causes regular cycles of marijuana-related symptoms (NIDA, 2019). This includes severe vomiting, nausea, and dehydration. Severe cases of Cannabinoid Hyperemesis Syndrome can even lead to emergencies where an individual needs medical attention. This shows the severity of the syndrome and the detrimental effects of marijuana on the physical body.

Substance Use

Using marijuana, especially in high dosages, can cause marijuana use disorder . This is when an individual becomes reliant on marijuana and cannot function properly without the substance. Three out of ten marijuana users can develop marijuana use disorder and starting usage at an early age increases the risks (Hasin et al., 2015; Lopez-Quintero et al., 2011). Since the legalization of marijuana made the substance more accessible, the risks of starting marijuana use at an early age have increased. This can lead to higher rates of marijuana use disorder. 

Additionally, marijuana can act as a “gateway” drug and lead individuals to experiment with other substances. THC-related studies on rats show that the subjects develop addiction-like behaviors that promote the use of other addictive substances (NIDA, 2019). If marijuana has the same effect on humans, it can promote the use of alcohol, cigarettes, and other drugs. This increases the risks of other forms of substance use disorder, such as heroin and cocaine addiction.

Increased Marijuana-Related Crimes

Marijuana use, along with its legalization, has increased the rate of marijuana-related crimes. Various universities and medical schools conducted studies that reported increased marijuana-related violence, traffic accidents, poisoning, and other crimes (cited in Evans, 2019). Since marijuana users can buy the substance legally, they are prone to purchase and use unsafe amounts. While there are regulations that limit the amount of marijuana that an individual can purchase at once, this does not stop them from stockpiling and using high dosages. This then leads to marijuana-related crimes since the public can consume the substance freely. Marijuana users may go out while under the influence of the substance, causing traffic fatalities and marijuana-related violence.

Along with increased crime rates are increased black market activities. The legalization of marijuana created competition for black market marijuana sellers. Since purchasing marijuana legally is better than risking jail time, black market sales have decreased. This forced black market sellers to offer other drugs, such as heroin and cocaine, which are more potent (Evans, 2019). Experts believed that marijuana legalization could hinder black market activities, however, it had a contrasting effect. With the black market selling more powerful and addictive drugs, the risks of substance use disorder and drug overdose increase. 

Cause Issues in Personal Life

Lastly, marijuana use can affect an individual’s social relationships. According to the Substance Abuse and Mental Health Services Administration (SAMHSA), marijuana users tend to have relationship problems and poor life satisfaction. This can be due to various factors, such as the marijuana stigma and other negative effects of substance use. Marijuana users may have problems getting a job, especially if they are very outspoken about their substance use. Negative effects, such as anxiety and mental disorders, can prevent an individual from having normal social interactions and relationships. This is most prominent in individuals who abuse marijuana since they are likely to develop the negative effects of the substance.

Second-Hand Marijuana Smoke

Marijuana use and legalization is a topic of debate not just because of its effects on an individual but also on others. Since marijuana users consume the substance by smoking it, nearby individuals may inhale second-hand marijuana smoke. Moore et al. (2011) conducted a study that found detectable levels of THC in children living with a marijuana user. This study shows that marijuana users can spread THC, and probably other chemicals, through second-hand smoke. While some studies show that a low dosage of marijuana has fewer adverse effects, second-hand marijuana smoke can be harmful to children and pregnant women. As mentioned earlier, marijuana is harmful to pregnancy and even small amounts of THC and other chemicals can cause adverse effects on children.


Marijuana use has many negative effects that harm an individual, those around them, and society. Infrequent marijuana use exposes an individual to negative short-term effects that lower their inhibitions. Frequent and abusive marijuana use can lead to serious mental issues, substance abuse, loss of IQ points, hinder brain development, harm to children’s health, and relationship problems. Additionally, the legalization of marijuana adversely affected marijuana-related crime rates and the black market. Marijuana use, especially irresponsible usage, causes negative effects; however, there is still a need for further marijuana-related research to assess fully the impact of the substance on humans and society.

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American Addiction Centers. (2022). Marijuana Abuse and PTSD. Available at . Accessed July 20, 2022. (2021). Marijuana: How Can It Affect Your Health. CDC. Available at Accessed July 20, 2022.

Evans, D. (2019). Marijuana Legalization Will Cause Many Problems for Missouri Law Enforcement and Schools. Missouri Medicine, vol. 116(3). Available at Accessed July 20, 2022.

Ganson, K., Murray, S., & Nagata, J. (2021). Associations Between Eating Disorders and Illicit Drug Use Among College Students. International Journal of Eating Disorders, vol. 54(7). Available at Accessed July 20, 2022.

Hasin D., Saha T., Kerridge B, Goldstein, R., Chou, S., Zhang H. …Grant, B. (2015). Prevalence of Marijuana Use Disorders in the United States Between 2001-2002 and 2012-2013. JAMA Psychiatry, vol. 72(12):1235-1242. Available at Accessed July 20, 2022. (2022). Know the Risks of Marijuana. Substance Abuse and Mental Health Services Administration. Available at Accessed July 20, 2022.

Lopez-Quintero C., de los Cobos J., Hasin D., Okuda, M., Wang, S., Grant, B., & Blanco, C. (2011). Probability and Predictors of Transition From First Use to Dependence on Nicotine, Alcohol, Cannabis, and Cocaine: Results of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Drug and Alcohol Dependence, vol. 115(1-2):120-130. Available at Accessed July 20, 2022.

Moore C., Coulter C., Uges D., Tuyay, J., van der Linde, S., van Leeuwen, A., Garnier, M., & Orbita, J., Jr. (2011). Cannabinoids in Oral Fluid Following Passive Exposure to Marijuana Smoke. Forensic Science International, vol. 212(1-3):227-230. Available at Accessed July 20, 2022.

NIDA (2021). What Are marijuana’s Long-Term Effects on the Brain? Available at Accessed July 20, 2022.

NIDA (2019). Cannabis (Marijuana) DrugFacts. Available at Accessed July 20, 2022.

Schmidt, S. (2021). Cannabis May Alter a Teen’s Developing Brain. Science News for Students. Available at Accessed July 20, 2022.

Weir, K. (2015). Marijuana and the Developing Brain. American Psychological Association, vol 46(10). Available at Accessed July 20, 2022.

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