Skip to content

Surprising Side Effects of Marijuana, Studies Say

Five marijuana side effects you might not know about.
FACT CHECKED BY Emilia Paluszek

The use of marijuana has become fairly mainstream, both as a recreational drug and for medical therapeutics. "As with nearly everything else about cannabis, how safe or dangerous it is remains hotly debated," says Peter Grinspoon, MD. "As a primary care doctor, I have to ask myself: is cannabis safer than the alternatives I would be prescribing? For example, if I'm treating a patient for chronic pain, is cannabis safer than opiates? Medication risks must be balanced against the safety concerns of cannabis." Here are five surprising side effects of marijuana you may not be aware of. Read on—and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had COVID.


Marijuana and Sperm

Sad man sitting on a bed, girlfriend in the background.

Studies show exposure to cannabis can alter the genetic profile of sperm. "What we have found is that the effects of cannabis use on males and their reproductive health are not completely null, in that there's something about cannabis use that affects the genetic profile in sperm," says Scott Kollins, Ph.D., professor in psychiatry and behavioral sciences at Duke University. "We don't yet know what that means, but the fact that more and more young males of child-bearing age have legal access to cannabis is something we should be thinking about."


Sleep Disruption

woman puts head down on desk, tired, stressed, burned out

While marijuana is widely used as a sleep aid, there is evidence that it can actually disrupt sleep. "At this time there still isn't any clear evidence that cannabis is helping sleep," says Dr. Bhanu Prakash Kolla, a sleep medicine specialist in the Center for Sleep Medicine at the Mayo Clinic in Rochester, Minnesota. "We know that when people initiate use there is some benefit in the immediate short term but there is quick tolerance to this effect. There currently is no good quality evidence to suggest that cannabis will help improve sleep quality or duration."

RELATED: Inflammation Calming Secrets That Really Work



Woman hands on his head felling headache dizzy sense of spinning dizziness with motion

Some doctors believe cannabis is strongly linked to an increased risk of psychosis and schizophrenia. "In the past month, I have treated 6 young men — adolescents or young adults — who presented to the ED with psychosis induced by vaping high-potency cannabis," says Wilfrid Noel Raby, PhD, MD.

"Adolescence and young adulthood are critical periods in which the use of a high-THC product can have a big effect on the structure and function of the developing brain," says Thorsten Rudroff, PhD.

RELATED: Sure Signs You Have Hypertension, Say Physicians


Impaired Vision

Mature woman takes off her glasses and massages eyes.

There is evidence that regular use of marijuana could lead to vision impairment: "Although visual acuity is the most widely used test to assess the state of visual function, there are other metrics that have been demonstrated to be more important for certain everyday tasks, for example, driving or reading," according to a study published in Scientific Reports. "One of these is contrast sensitivity, and our results have shown that this parameter is significantly worse after smoking cannabis." 

RELATED: How an "Unhealthy" Gut Impacts Your Health, According to Experts


Panic Attacks

Man suffering from a stress attack

"It happens from direct effects of the drug in the brain and/or direct effects of the drug on the body," says Ryan Vandrey, Ph.D. "Cannabis can modulate neurotransmitters in parts of the brain that control anxiety and elevate your heart rate. There's no one way to treat this. When it does happen in our lab we respond to the needs of the individual. We encourage people to get comfortable and provide them with whatever they need — whether that's food, or water, or sometimes just to close their eyes, lie down and relax."

Ferozan Mast
Ferozan Mast is a science, health and wellness writer with a passion for making science and research-backed information accessible to a general audience. Read more about Ferozan
Filed Under