Experts Warn Recreational Marijuana Use More Harmful Than You Might Think

THC, which is found in marijuana, can disrupt normal mental and physical functions, including memory, concentration, movement, and coordination.

By Kari Apted | Updated


April 20, or 4/20, is known by some as a day to celebrate the use of marijuana. With 37 states, plus Washington DC having a comprehensive medical cannabis program and another 21 legalizing weed for recreational use, the United States is trending toward widespread legalization. But marijuana is still a drug, and experts warn that regular use can cause more damage than we realize.

There are various theories on why 420 became the code number for marijuana, but there is no question that more Americans are partaking of the devil’s lettuce. An August 2022 Gallup poll called Americans and the Future of Cigarettes, Marijuana, Alcohol found that more people in the US now smoke weed than tobacco. Although both plants provide positive, pleasurable feelings for the user, they also come with significant downsides.

Katia Hetter, Senior Editor for CNN Science and Wellness, recently interviewed CNN Medical Analyst Dr. Leana Wen to learn more about the research on marijuana use and how it affects users. Dr. Wen has concerns about recreational marijuana use, especially for young people and pregnant women. Her opinions are based on her previous position as chair of Behavioral Health System Baltimore, where she oversaw policy and services regarding addictive substances.

One of the active ingredients in marijuana is a psychoactive compound called tetrahydrocannabinol, or THC. “It’s similar to compounds that are naturally occurring in the body called cannabinoids and can mimic their function by attaching to cannabinoid receptors in the brain,” said Dr. Wen. “In so doing, THC can disrupt normal mental and physical functions, including memory, concentration, movement, and coordination.”

Wen urges marijuana users and would-be users to be cautious, but she also believes that it’s important to keep researching the medical uses of cannabis. It is currently approved for a limited number of therapeutic uses, including the treatment of nausea in cancer patients undergoing chemotherapy and stimulating the appetite in AIDS patients. There are currently clinical trials going to evaluate the use of marijuana to treat neuropathic pain, muscle stiffness, and overactive bladder.  

One problem is that some users self-treat with marijuana to alleviate pain, depression, or anxiety. While this is understandable due to the drug’s ability to generate feelings of happiness and relaxation, these effects are short-lived. The user often develops tolerance, requiring more and more marijuana to obtain the same effect.

The National Institute on Drug Abuse says that using marijuana can cause impaired thinking and interfere with the ability to learn. It can also impair the parts of the brain that regulate posture, balance, and reaction time. “THC stimulates the neurons involved in the reward system that release dopamine, or the ‘feel-good’ brain chemical, which contributes to its addictive potential,” said Wen.

The developing brains of babies, children, and teenagers are especially susceptible to the more harmful effects of marijuana and THC. The effect is so well-known that the Centers for Disease Control (CDC) have linked marijuana use during pregnancy to children with cognitive and behavioral problems. They also warn against secondhand smoke exposure.

Adolescents and young adults who use the drug also experience negative impacts on their memory, attention, learning, and motivation. Regular teen use of cannabis is associated with dropping out of high school and having lower IQ scores later in life. At the university level, those who use marijuana have lower grade point averages.

While Wen emphasized that there is still a lot to learn about the long-term effects, it has been shown that daily use can increase the risk of heart disease by one-third. And as many as three in 10 users experience a condition known as marijuana use disorder. “Signs of this disorder include trying but failing to quit using; continuing to use it even though it is causing problems at home, school or work; and using marijuana in high-risk situation. Dome individuals, especially those who use large amounts, experience withdrawal symptoms when they try to stop,” Wen said.

The Gallup poll showed that Americans are split on whether marijuana use is a good thing, with half of the respondents saying it is neither harmful for users nor for society as a whole. However, the causal acceptance of cannabis use is still a relatively new phenomenon. It is likely that attitudes toward recreational use will change if the downsides of smoking pot become more apparent in the years ahead.