Research on marijuana use continues to reveal health risks and misconceptions about its effects, according to experts at the University of California, San Francisco (UCSF). As marijuana becomes more accessible and widely used, scientists urge the public to reconsider assumptions about its safety.
Despite popular belief that marijuana smoke is less harmful than cigarette smoke, UCSF researchers say inhaling any kind of smoke can damage cardiovascular and respiratory health. “There’s a misconception that marijuana, being more ‘natural’ than highly processed cigarettes from tobacco companies, produces smoke that is less toxic,” says Matthew Springer, PhD, a professor of cardiology. “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 cannabis products are sometimes seen as a safer alternative because they do not involve smoking. However, these products carry their own risks due to delayed onset of effects. Laura Schmidt, PhD, MSW, MPH, professor of health policy studies at UCSF notes: “There’s a mythology…that marijuana is a benign product that doesn’t cause significant intoxication. That’s unrealistic today, with commercialized cannabis.” She points out that edibles often mimic junk food and may encourage overconsumption.
The slower effect of edibles can lead users to ingest too much before feeling the drug’s impact. Springer explains: “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.”
Recent UCSF research has also linked chronic marijuana use—whether smoked or ingested—to impaired blood vessel function. In the CANDIDE study led by Leila Mohammadi, MD, PhD: “Using cannabis makes a 30-year-old’s blood vessels resemble those of a 60-year-old,” Mohammadi says. The study found both smokers and edible users showed signs of vascular dysfunction; however only smokers’ blood caused additional harm in lab tests.
Marijuana use during adolescence presents additional concerns due to ongoing brain development until around age 25. William Burrough, MD, MPH states: “IQ tests are lower in people who use marijuana heavily…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 adds there is potential for recovery if young people reduce or stop usage.
While overdose deaths from marijuana are rare compared to opioids like fentanyl (https://www.cdc.gov/drugoverdose/deaths/index.html), severe intoxication can still result in anxiety or psychosis—especially among those with family histories of mental illness.
Experts caution against self-medicating with cannabis for conditions such as depression or anxiety due to insufficient evidence about benefits versus regulated medications (https://nccih.nih.gov/health/marijuana-cannabinoids). Suzaynn Schick PhD ’01 notes: “Many people are drawn to marijuana because it’s easily accessible…I hear a lot of magical thinking around marijuana…” Nhung Nguyen adds regulation challenges make it hard to draw conclusions about efficacy.
Discussing cannabis use openly with healthcare providers can help individuals weigh risks against other treatment options. Meredith Meacham PhD encourages patients not to fear stigma when talking with clinicians about their substance use habits.
Finally, quitting regular cannabis use may be difficult for some individuals due to withdrawal symptoms such as anxiety or sleep disturbances—a sign of possible cannabis use disorder (https://www.samhsa.gov/mental-health/substance-use). Burrough remarks: “Addiction happens when you lose control over that thing…The good news is there are ways we can help.”
Experts recommend speaking with medical professionals before starting or stopping marijuana use so patients can make informed decisions based on current scientific knowledge.
