Wellness·6 min read

How Marijuana Could Impact Your Health

Marijuana and your brain
Releaf - Medical Cannabis
September 16, 2021

Pot. Weed. Mary Jane. Marijuana. This drug goes by many names and serves many needs — including medical ones — but its health impacts are hazy. 

I smell weed in the park, but how common is it these days? 

Very. Marijuana is one of the most commonly used drugs in the US, with approximately 22.2 million users each month. Recreational use has been legalized in 19 states, plus Washington, DC and Guam. It’s also been approved for medical use in 37 states. About half of adult Americans have tried marijuana at least once in their lives and about two-thirds of Americans say that marijuana use should be legal. It’s been a longgg road from vilified drug to an accepted norm and now a medical treatment. 

Gimme some background. 

Marijuana has long been stigmatized in the US - for more than a century. Around the time that Prohibition was repealed in the 1930s, teetotaling lawmakers turned their attention towards pot. At the time, it was associated with Mexican-American communities, whose populations had grown during a wave of immigration following the 1910 Mexican Revolution. This, coupled with the fear of immigrants taking American jobs during the Great Depression, prompted a wave of marijuana crackdowns. And in 1937, the federal gov passed an act that effectively criminalized the drug. Fast forward to today, and it’s been decriminalized in multiple states. Still, marijuana-related arrests disproportionately affect people of color. According to the ACLU, Black people in the US are nearly four times as likely as white people to be arrested for possession, even though usage rates are similar. Its perception is influenced by the drug’s history in this country, politics, and Hollywood.  

What should I know about its effects on my health? 

First, there's a lot we don’t know. Researchers are *shrugging emoji* on the full effects of marijuana on the body and brain (especially the still-developing brain. Think: teenagers). That’s partially because restrictive policies at the federal and state levels have limited research in the US.

Here’s what we know so far about how marijuana impacts our bodies...

The good: 

Marijuana’s been decriminalized in more than half of US states for a reason. The drug can positively impact people with conditions like…

  • Cancer 

    • Studies of marijuana plant chemicals found they can be helpful in treating nausea and vomiting caused by chemotherapy.

    • There’s evidence to suggest that cannabinoids (the compounds found in the plant) may have anticancer effects. Meaning they may help discourage cancer cells from multiplying and slow tumor growth. 

    • Animal studies have shown some cannabinoids may even kill certain cancer cells.

  • Chronic Pain 

  • Mental Health 

    • Marijuana can relieve symptoms of depression and PTSD in some patients.

    • In recent years, many people have used products with cannabinoids to self-medicate for certain mental health conditions like depression and anxiety. Pssst…CBD and THC are both compounds found in the cannabis plant — but CBD doesn’t get you high, while THC does. More on CBD here

  • Other Potential Uses 

    • Alzheimer’s: Severe weight loss can be a symptom of Alzheimer’s, and marijuana has been used to help patients gain weight. Research has also found that it can make patients less agitated.

    • Multiple sclerosis (MS): In adults with MS, use of oral cannabinoids (think: sprays and capsules) may improve symptoms like pain and muscle spasms.

    • COVID-19: Early research suggests that CBD might be able to fight the virus by stopping it from replicating inside the body. But this research has only been done in lab cell and mouse tests. Clinical trials would have to prove it works. And so the researchers said 'hold off' on using it in any way (read: smoking and eating or drinking) in hopes that it'll protect you.

The not-so-good: 

It’s not all pain relief and snack cravings. Here are some negative side effects of marijuana use…

  • Dependence

    • The CDC estimates that about 1 in 10 marijuana users will become addicted.

    • You may also develop “marijuana use disorder,” aka withdrawal symptoms like irritability, trouble sleeping, and chills. 

  • Mental Health 

    • While there are positive mental health effects for some people (see above), others experience the opposite. For some people, the drug can cause disorientation, and sometimes unpleasant thoughts or feelings of anxiety and paranoia.

    • Marijuana users may face increased risk for psychiatric disorders, including psychosis. But it’s unclear whether those who are predisposed to a disorder like schizophrenia are just also more likely to develop cannabis use disorder. More research needs to be done. For teens, marijuana use has been linked to depression and suicidal thoughts. 

  • Pregnancy 

    • Again, research is limited, but with regular use, THC can get into breast milk. It can also be transmitted from mother to baby while pregnant, and may negatively impact a baby's developing brain. But there’s not enough long-term data to make all doctors say “put down the pot.” Overall, though, medical guidelines tell you to avoid smoking marijuana while pregnant or breastfeeding. 

    • Use by pregnant people may be linked to issues with attention and behavioral problems in their kids. 

  • Brain health 

    • THC directly affects the parts of the brain responsible for short-term memory, learning, attention, coordination, and reaction time. This means that heavy marijuana users (think: every day, sometimes multiple times per day) can have problems in those areas. However, a recent study found that medical users may experience positive brain effects (better cognition, memory, and mood) after a few months of using marijuana. 

    • The drug may be especially damaging for teenagers’ developing brains, negatively impacting attention span, memory capacity, and the ability to learn. A recent study showed that peoples’ driving ability was negatively affected by heavy marijuana use even when they were sober, especially those who began regularly using the drug before age 16. 

  • Heart Health 

  • Lung Health 

    • Cannabis smoke contains carcinogens, which could increase the risk of lung cancer

    • Marijuana smoke irritates the lungs, and people who smoke it frequently can have similar breathing problems as those who smoke tobacco. It can cause your body to produce phlegm and increase the risk of bronchitis.

    • PSA: Secondhand smoke might also be on the “not-so-good” list. We know that secondhand cigarette smoke is bad, and it’s raised some Qs about second-hand marijuana smoke. But there hasn’t been enough research to come to a conclusion (sensing a pattern?). One study on rats found that secondhand marijuana smoke impaired blood vessel function longer than cigarette smoke. But that’s one study. On rats. 


Marijuana legalization has caught on in the past few years, but the health effects of the drug are largely up for debate. More research needs to be done to fully understand its long term impact on the brain and body — and to clarify if and when there’s a case for lighting up.

This content is for informational and educational purposes only. It does not constitute a medical opinion, medical advice, or diagnosis or treatment of any particular condition. 

Photo credit: Releaf - Medical Cannabis

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