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Dangerous Side Effects of Smoking Marijuana, According to Science

Cannabis could help your health but can also cause unwanted problems.

Cannabis has seen an ever-increasing acceptance within society in the past few years. There are now 35 states that allow for at least the medical use of cannabis, with Mississippi and South Dakota being added to the list this year. Although many people believe there are great uses of cannabis, such as for pain or depression, there are obvious side effects. As an Emergency Physician, I see these side effects of cannabis use very often. Read on—and to ensure your health and the health of others, don't miss these Sure Signs You May Have Already Had COVID.


You Might Feel Nausea and Vomiting

Middle aged woman suffering from abdominal pain while sitting on bed at home

One of the most common side effects that is not well known is that it can cause severe nausea and vomiting. The condition, called cannabis hyperemesis syndrome, is usually seen with daily users but can occur in any patient. It is characterized by nausea and vomiting that can need IV fluids and anti-nausea medications. Most patients describe that these symptoms improve with hot showers or using creams made from the active ingredient found in chili peppers, capsaicin. Although the symptoms can be managed, the best treatment is complete abstinence from cannabis. 



You Might Feel Anxiety

depressed Indian woman holding head in hands, sitting alone on couch at home

Cannabis is used for some patients who have depression or anxiety. There is a subset of patients who will experience a paradoxical effect. Some patients will have severe anxiety and even paranoia after use. Most patients can connect the anxiety with the use of marijuana that contains high levels of tetrahydrocannabinol or THC. Some patients find their anxiety is lessened with cannabis products that are higher in CBD or cannabidiol. If you are using cannabis for the treatment of depression and anxiety, it is important to work closely with a physician to ensure appropriate treatment.

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You Might Feel Hunger


It is difficult to see cannabis in popular movies or television that does not highlight the "munchies" that occur. For some patients, particularly cancer patients or AIDS patients, cannabis is specifically used for the treatment of their complete lack of appetite. Although helpful for some patients, increased hunger can lead to detrimental side effects, such as obesity, high blood pressure, and diabetes. If you are going to be using cannabis for medical treatment, it is important to track your caloric intake and monitor your weight. 


You Might Feel Sedation or Impairment

Man worker forklift driver with protective mask working in industrial factory or warehouse.

As with many medications, there is the possibility of decreased attention and increased sedation with cannabis use. This can lead to dangerous conditions if the patient is operating heavy machinery or even driving. Consumer Reports published an article last year confirming that in states that have legalized cannabis usage, auto accidents have increased in comparison to their neighboring states. The article goes on to describe that possibly 50% of medical cannabis patients drove while under the influence. It is essential to realize the sedative features of cannabis and avoid driving or operating heavy machinery.

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You Might Develop Psychiatric Health Concerns

woman hold head in hands suffer from grief problem, depressed lonely upset african girl crying alone on sofa at home

Depression and anxiety are certain diagnoses that proponents of cannabis use state are safely treated. There is data suggesting, however, that cannabis can be problematic in patients with other psychiatric illnesses such as schizophrenia. Some studies suggest there is a direct correlation between the usage of cannabis as a teenager and the development of schizophrenia later in life.

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You Might Feel Dry Mouth

woman, annoyed, frustrated fed up sticking her finger in her throat

Specifically, for patients who use cannabis by smoking, dry mouth can be a very common side effect. Although it seems more of a nuisance than a true side effect, dry mouth can have some major health concerns. Good oral health, such as gum and dental health, requires a moist environment. With drying out of the oral cavity, there can be a regression of the gums which can lead to tooth decay and even teeth falling out. 

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You Might Foster Decreased Sperm Health

Sperms viewed from the microscope

Cannabis has been found to reduce sperm viability in a number of different ways, one of which being the number of sperm produced. In a study in Denmark, weekly use of cannabis was found to reduce the number of sperm. Other studies have looked at the health of the sperm in patients who use cannabis regularly. There seems to be a correlation with cannabis use and sperm that do not have appropriate forward movement, or appropriate ability to contact and thereby fertilize the egg within the female reproductive tract.

There has been a major push to legalize the use of cannabis for medical treatment of many different disorders. Although there is anecdotal evidence of its benefits, specifically in seizures and chronic pain, it is not without side effects. It is important to consult your physician before starting any medical treatment, including cannabis. As for yourself: To get through this pandemic at your healthiest, don't miss these 35 Places You're Most Likely to Catch COVID.

Kenneth Perry, MD FACEP
Dr. Perry is an active practicing physician and Medical Director of an Emergency Department in Charleston, South Carolina. Read more about Kenneth