Marijuana remains a topic of discussion as more states consider changes to its legal status and public attitudes shift. However, health experts from the University of California, San Francisco (UCSF) are addressing common myths about marijuana’s effects on the body, emphasizing that both smoking and ingesting cannabis can have health consequences.
Matthew Springer, PhD, professor of cardiology at UCSF, notes that some people believe marijuana smoke is less harmful than cigarette smoke because it is perceived as more “natural.” He counters this idea: “There’s a misconception that marijuana, being more ‘natural’ than highly processed cigarettes from tobacco companies, produces smoke that is less toxic,” says Springer. “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.”
Edible forms of marijuana are often considered safer because they do not involve inhaling smoke. Laura Schmidt, PhD, MSW, MPH, professor of health policy studies at UCSF, explains how commercialized cannabis products differ from those in the past: “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,” she says. She points out that edibles now come in brightly colored packaging and may resemble candy or junk food.
Springer also highlights risks associated with edibles: “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,” he says.
Long-term health effects are another area of concern. Leila Mohammadi, MD, PhD—lead clinical investigator for UCSF’s CANDIDE study—reports findings linking chronic cannabis use to cardiovascular issues similar to those seen in tobacco smokers. The study found problems with blood vessel function in both smokers and users of edibles: “Using cannabis makes a 30-year-old’s blood vessels resemble those of a 60-year-old,” Mohammadi says.
The impact on young people is also highlighted by William Burrough, MD, MPH: “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 explains. However, Burrough adds that recovery is possible if use stops: “While repeated cannabis use during adolescence can cause long-lasting changes, stopping or reducing it can lead to recovery and improvement in brain function. The body’s ability to heal is remarkable.”
Regarding overdose risk and mental health impacts: “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,” Burrough says. He notes particular risk for individuals with family histories of schizophrenia or psychosis.
On self-medicating with marijuana for conditions like depression or anxiety—Suzaynn Schick, PhD ’01 remarks: “Many people are drawn to marijuana because it’s easily accessible… I hear a lot of magical thinking around marijuana.” Nhung Nguyen, PhD PharmD adds there is still limited evidence regarding benefits due to lack of standardized regulation: “It’s hard to make conclusions about the effects without standardized product regulation.”
Springer recognizes certain situations where medical use may be justified: “Clearly if a cancer patient can’t keep food down…and this is what makes them feel better…that’s a beneficial use.” Burrough emphasizes balanced conversations: “Maybe cannabis isn’t as harmful as some other potential substances. At the same time…using it too often can lead to real harm.”
Discussing openness between patients and doctors about marijuana use Meredith Meacham PhD MPH says clinicians strive for nonjudgmental discussions: “They try to have nonjudgmental open-ended conversations…‘Is it OK if we talk about cannabis? Tell me about your use.’”
Burrough contrasts known treatments for depression with unregulated options like marijuana: “We have strong evidence from randomized controlled trials showing which antidepressant medications are effective…They are regulated and monitored.”
Quitting regular marijuana use may not be easy for everyone; withdrawal symptoms such as anxiety or sleep disruption can occur within days after stopping heavy use—a sign of possible dependence.
Treatment options include behavioral therapies or medications targeting symptoms or underlying issues like anxiety or depression. As Burrough notes: “Addiction happens when you lose control over that thing…The good news is there are ways we can help.”
