Marijuana use has become more common, but health experts say many beliefs about its safety and effects are not supported by current research.
Matthew Springer, PhD, professor of cardiology at UCSF, addressed a common assumption about marijuana smoke: “There’s a misconception that marijuana, being more ‘natural’ than highly processed cigarettes from tobacco companies, produces smoke that is less toxic. But that’s not the case. It’s nasty stuff, with benzene, formaldehyde, and heavy metals you don’t want to be exposed to, among many other substances.”
Edibles are often seen as a safer alternative to smoking marijuana. Laura Schmidt, PhD, MSW, MPH, professor of health policy studies at UCSF said: “There’s a mythology, popularized by the comedians Cheech and Chong in the 1970s, that marijuana is a benign product that doesn’t cause significant intoxication. That’s unrealistic today, with commercialized cannabis. We’ve never had cannabis this potent or abundant. We’ve never had cannabis commercialized or packaged like food. Many cannabis edible products mimic junk food. Bright colors, cartoon characters. They’ll just change the name: Molly Ranchers versus Jolly Ranchers.”
Springer noted another risk: “Someone will take an edible and five minutes later they’ll say, ‘I don’t feel it – I’m going to take more,’ and end up taking way too much. They rush to the emergency room with panic, palpitations, and nonstop vomiting.”
Research from UCSF shows long-term marijuana use may have negative effects on cardiovascular health similar to tobacco smoking. In UCSF’s CANDIDE study led by Leila Mohammadi, MD, PhD: chronic cannabis smokers were found to have vascular defects comparable to those of chronic tobacco smokers. These included poorly functioning arteries and blood serum that inhibited important properties of cultured endothelial cells—an early sign of potential cardiovascular conditions such as hypertension and atherosclerosis.
The study also observed people who used only edibles experienced arterial problems but their blood did not harm lab-grown endothelial cells in the same way as smokers’ blood did. This suggests different impacts on blood vessel function between smoked and ingested marijuana.
“Using cannabis makes a 30-year-old’s blood vessels resemble those of a 60-year-old,” Mohammadi said.
William Burrough, MD, MPH—a pediatrics assistant professor—explained risks for younger users: “IQ tests are lower in people who use marijuana heavily, particularly during adolescence. Studies using brain scans have shown teenagers who frequently use cannabis have reduced brain matter and activity in the areas crucial for decision making and planning.” He added that while some changes may be long-lasting if usage stops or decreases recovery is possible due to brain adaptability.
Burrough also commented on overdose risks: “Marijuana doesn’t impact the body the way fentanyl and other opioids do, but people can become so intoxicated from it that they experience anxiety, paranoia, hallucinations, and sometimes psychosis… Anyone can be affected by substance use, but if you have a family member who has schizophrenia or psychosis it can be particularly risky.”
Suzaynn Schick PhD ’01 pointed out why some turn to self-medication: “Many people are drawn to marijuana because it’s easily accessible… I hear a lot of magical thinking around marijuana often from people who feel they don’t have better safer alternatives.”
Nhung Nguyen PhD PharmD stated there is no clear evidence yet for presumed benefits in treating conditions like depression or anxiety because products lack standardization.
Springer said medicinal uses remain an area for further research but noted: “Clearly if a cancer patient can’t keep food down…and this is what makes them feel better then to me that’s a beneficial use.”
Burrough emphasized open dialogue: “These conversations get so caught up in people’s personal feelings…Maybe cannabis isn’t as harmful as some other potential substances. At the same time using it too often can lead to real harm. Ideally I’d want people to talk to their doctor about their use.”
Meredith Meacham PhD MPH advised patients should feel comfortable talking with providers about marijuana since clinicians aim for nonjudgmental conversations about substance use.
Burrough explained when considering treatments for depression he tells patients there is strong evidence supporting regulated antidepressant medications over unregulated options like marijuana.
For those struggling with quitting daily cannabis use withdrawal symptoms such as anxiety sleep disruption or poor appetite may occur indicating possible dependence requiring professional help.
Burrough concluded: “Many things can be addictive – shopping gambling even social media…Addiction happens when you lose control over that thing when it’s impacting your daily life in negative ways. The good news is there are ways we can help…it’s often a combination of options catered to your goals that leads to success.”
