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Cannabis Risks & Benefits: A Delicate Dance

drjoelasek

Updated: Feb 2




Over the course of my career, I’m not sure that I have seen any substance surrounded by more controversy than cannabis, commonly known as marijuana. While it has been used for recreational, spiritual and medicinal purposes for thousands of years, over the past few decades, there has been a significant shift in terms of its acceptability, accessibility and potency. While many people use it safely for recreational and medicinal purposes, there are several potential risks associated with its use. Unfortunately, these risks appear to have grown significantly in the last few years, and I anticipate will only continue to grow because of current trends that we are seeing with its use.


In this post, I outline some of the risks and potential benefits I see with cannabis use and research that continues to come out on an almost weekly basis.


First and foremost, my biggest concern is the relative dearth of good research on both its risks and potential benefits. Due to its federal classification as a level 1 controlled substance, research on cannabis was inhibited for several decades, which left us with limited data regarding its safety and efficacy compared to other substances. Fortunately, as cannabis legalization has progressed, research efforts have ramped up, though I’d emphasize many findings are still extremely preliminary.


With regard to its potential medicinal benefits, a review published in the British Medical Journal highlights the following three medical conditions where cannabis or its derivatives show potential benefits:

 

A summary of these findings:

  • Chronic Pain: Cannabis may provide some relief for certain types of chronic pain, especially neuropathic pain (pain resulting from nerve damage). However, the evidence is mixed, and cannabis often carries increased risks for side effects, including a higher likelihood of harm compared to other treatments.

  • Nausea and Vomiting: In the case of chemotherapy-induced nausea, cannabis (specifically pharmaceutical-grade CBD) has shown some promise. However, once again, head to head studies, have not shown superiority of cannabis and it tends to have more side effects compared to standard treatments.

  • Epilepsy: High-dose, pharmaceutical-grade CBD has demonstrated effectiveness in treating certain forms of epilepsy, though the studies do not involve plant-based cannabis products, instead using highly refined CBD products which eliminate toxins/adulterants commonly found in CBD based supplements: What You Need to Know (And What We’re Working to Find Out) About Products Containing Cannabis or Cannabis-derived Compounds, Including CBD | FDA.


Other reviews describe evidence for cannabinoids in chronic pain as weaker:

· A 2017 meta-analysis of 27 studies examining the effectiveness of cannabis in chronic pain found the quality of evidence for cannabis in alleviating neuropathic pain (pain due to damages nerves) to be weak

· Notably, they also found no evidence supporting the use of cannabis in other types of pain.


Caveats and Concerns:


  • Lack of superiority: There is little evidence to suggest that cannabis is more effective than other available treatments for conditions like chronic pain.

  • Risk of side effects: A significant concern is the risk of adverse effects, with a "number needed to treat" (NNT) for meaningful pain reduction at 24 and a "number needed to harm" (NNH) at 6, indicating that side effects may be more likely than benefits.

 

Additionally, cannabis shows some limited evidence for:

  • Increasing appetite in conditions like HIV/AIDS.

  • Alleviating symptoms of Tourette syndrome.

  • Improving outcomes after traumatic brain injury or intracranial hemorrhage.


However, there is no strong evidence supporting cannabis for conditions like dementia, glaucoma, or chronic depression associated with multiple sclerosis.


Mental Health and Cannabis Use

Mental health is another area where cannabis has generated both interest and concern. A recent systematic review examined the efficacy of cannabinoids in treating various mental disorders such as anxiety, depression, PTSD, psychosis, and ADHD. The results are inconclusive, but a few key points stood out:


  • Anxiety Disorders: Limited evidence suggests that cannabinoids might help with anxiety, at least in the short term. As discussed below, long term use of cannabis may actually worsen anxiety, not dissimilar to some other medications commonly prescribed for anxiety


  • PTSD: Despite some early reports suggesting cannabis could alleviate PTSD symptoms, a randomized controlled trial found no significant differences in PTSD symptom severity between cannabis and placebo.


  • Other Psychiatric Disorders: No substantial evidence supports cannabis use for conditions like depression, psychosis, or ADHD.


These findings underscore the need for more robust, high-quality research before cannabinoids can be recommended for psychiatric indications.


Risks of Cannabis Use

While benefits of cannabis for medical conditions is still quite limited, more and more people are using it recreationally. While limited use of cannabis (2-3 days a week) and using lower potency forms (less than 15% THC content) is likely safe for most folks, more regular use and use of higher amounts can lead to problems that range from minor to life-threatening.


This is getting more media attention as marijuana moves toward full legalization and overall use grows significantly:


Below I outline the risks associated with cannabis use, ranging from mental health issues to physical health concerns.


1. Mental Health Problems

Regular cannabis use has been linked to several mental health issues:


  • Anxiety and Paranoia: Cannabis can induce anxiety or panic attacks in some users, sometimes leading to cannabis-induced anxiety disorder, which affects 20-25% of those who present to emergency rooms with cannabis-related symptoms.


  • Depression and Mania: Cannabis may trigger or worsen symptoms of depression, bipolar disorder, and other mood disorders, particularly in those with a family history of mental illness.


  • Suicide Risk: Studies have shown a correlation between cannabis use and increased risk of suicidal thoughts and behaviors, particularly among young adults.


  • PTSD Worsening: Contrary to some beliefs, cannabis use may worsen PTSD symptoms, with studies showing increased severity of symptoms, violent behavior, and substance abuse among veterans who used cannabis.


  • Psychosis: Frequent or heavy cannabis use increases the risk of developing psychosis, especially in individuals genetically predisposed to mental health conditions.


  • Sleep Disruptions: Chronic cannabis use can interfere with REM sleep, which is essential for memory, mood regulation, and overall brain health. While cannabis can cause people to feel sleepy and get to sleep more easily, there is no evidence that it helps quality of sleep and that it is safe or effective in the treatment of insomnia.


2. Cognitive Impairment

Cannabis can affect cognitive functioning, especially when used frequently:


  • Memory and Learning: Cannabis impairs short-term memory, making it harder to recall information or concentrate on tasks.


  • Attention and Focus: Users typically experience difficulty maintaining attention or focus, particularly when under the influence.


  • Impaired Coordination: Cannabis affects motor skills and reaction times, leading to an increased risk of falls and accidents, especially when driving.


3. Addiction and Dependence

Cannabis use can lead to dependence in some individuals:


  • Cannabis Use Disorder: Some individuals can develop a dependence on cannabis, experiencing cravings and withdrawal symptoms when not using it. More than one-fifth of people who use cannabis struggle with dependency or problematic use, according to a study published in The Journal of the American Medical Association Network Open. The research found that 21 percent of people in the study had some degree of cannabis use disorder, which is characterized broadly as problematic use of cannabis that leads to a variety of symptoms, such as recurrent social and occupational problem. In the study, 6.5 percent of users suffered moderate to severe disorder.  Also, concerningly, given the promotion of cannabis for treatment of medical conditions, individuals who use cannabis for medical reasons may be at higher risk due to more frequent use and use of higher-potency strains: Medical marijuana may trigger substance abuse


  • Risk Factors for a Use Disorder/ Dependence: Younger age at first use, high frequency of use, use of more potent cannabis (THC content of greater than 15%) and genetic predisposition can increase the likelihood of developing a disorder.


  • Withdrawal Effects: with more regular use (especially daily use) and with use of higher THC concentrations (15% or greater), the chance for physical dependence increases significantly. When one is physically dependent, they experience withdrawal when THC levels decrease. This can happen as soon as a few hours after use, such as when awakening after using cannabis the night before. The most common withdrawal symptoms include sleep problems, anxiety and gastrointestinal symptoms (nausea, abdominal pain, constipation/diarrhea, etc.) The only way to alleviate these symptoms, is to use more cannabis, thus creating a vicious cycle. The only way to break this cycle, is to take a tolerance break


4. Physical Health Risks

Cannabis use can negatively impact various physical health aspects:


  • Respiratory Effects: Smoking cannabis can lead to acute or chronic bronchitis and other respiratory problems due to the inhalation of harmful chemicals. Smoking marijuana may do more damage to lungs than cigarettes: Marijuana may be more harmful to lungs than cigarettes, study suggests Combining tobacco with cannabis appears to significantly increase those risks. Furthermore, possible severe lung injury may arise from vaping cannabinoids.


  • Cardiovascular Effects: Cannabis can increase heart rate, blood pressure, palpitations and atrial fibrillation. It may pose increased risks for individuals with preexisting heart conditions. Frequent cannabis use may raise the risk of heart attack and stroke, a study in the Journal of the American Heart Association has found. The researchers found that participants who used cannabis daily by any means had a 25% increased likelihood of heart attack and a 42% increased likelihood of stroke compared with participants who did not use cannabis.


  • Gastrointestinal Effects: The THC in cannabis is a potent activator of CB-2 receptors in the GI system, which accounts for some cannabis effects such as reducing nausea and increasing hunger (i.e. the munchies.) With more regular use, THC can suppress CB-2 receptors and lead to negative GI effects including cramping, pain, discomfort with eating, and constipation/diarrhea mimicking symptoms of IBS.


    Eventually one may develop cannabinoid hyperemesis syndrome (CHE), which is a form of cyclic vomiting that is accompanied by abdominal pain and occurs during or within 48 hours after frequent and heavy cannabis use. CHE is a major reason for cannabis-related visits to emergency departments. It’s identified by its temporal association with cannabis use, relief with hot baths or showers, and resolution with extended abstinence from cannabis. Many people have difficulty accepting the diagnosis and continue using cannabis to self-medicate. The symptoms of cannabinoid hyperemesis syndrome are treated with haloperidol and topical capsaicin. Traditional antiemetic agents are usually ineffective. The only effective long-term treatment is total abstinence from cannabis. Any return to use leads to return of gastrointestinal symptoms in virtually all cases.


  • Increased Cancer Risk: One study shows that cannabis use increases the risk for head and neck cancer by as much as 800%, especially with more frequent use: Daily marijuana use linked to deadly head and neck cancers, study finds | CNN Risks for other cancers is still being assessed.


  • Hormones:  effects on testosterone are not firmly established, but one study suggested it suppresses testosterone, reduces sperm count/ concentration


5. Developmental Risks

Cannabis use during pregnancy and adolescence carries significant risks:

The American College of Obstetricians and Gynecologists recommends against cannabis use during pregnancy and nursing.


  • Pregnancy: Pregnant people who use cannabis expose their neonates. In utero exposure is associated with increased risk among newborns of preterm birth (12.0% among cannabis users, compared with 6.1% among nonusers), having low birth weight, being small for gestational age, and being admitted to the neonatal intensive care unit, but cannabis use is not associated with adverse maternal outcomes.


  • Breastfeeding: THC appears in breast milk at concentrations several times higher than concentrations in the bloodstream and may persist for up to 2 days after the most recent cannabis use. Cannabis use changes the composition of breast milk; it increases the concentration of lactose and decreases the concentration of secretory immunoglobulin A (the major antibody in breast milk). Long-term effects on infants fed with breast milk are unclear; the majority of persons using cannabis while breast-feeding an infant also used cannabis during pregnancy.


  • Early childhood effects: The association of in utero exposure with long-term neurodevelopmental outcomes remains unclear.  There is low-quality evidence of subtle impairment in cognitive function and an increased risk of substance use and delinquent behavior during childhood and adolescence.


    In one study, the researchers tracked confirmed diagnoses of attention-deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD) and intellectual disability among the hundreds of thousands of children studied. They found that kids born to moms who used cannabis during pregnancy had 98% higher odds for ADHD, and 94% higher risk for an autism spectrum disorder, compared to the children of women who did not use cannabis. These kids also had a 46% higher risk for developing an intellectual disability versus children whose moms did not use cannabis while pregnant. And the kids of women who smoked cigarettes and cannabis while pregnant had even higher risks for a developmental disorder.


    Concerningly, another study showed prenatal exposure to Cannabis is tied to aggression, Poorer Executive Function at Age 5.

 

  • Adolescents and Young Adults: Cannabis use during critical developmental periods can impact brain development, potentially leading to long-term cognitive deficits and increased risk of mental health issues including anxiety, depression, substance use disorders and schizophrenia. It has also been directly linked to brain damage in adolescents in this study.


6. Interactions with Other Substances

Cannabis can interact negatively with alcohol, other drugs, and many common medications, amplifying impairments and increasing the risk of overdose or dangerous side effects.


7. Legal and Social Consequences

As cannabis becomes legal in more areas, its social and legal implications are evolving:


  • Legal Risks: Driving under the influence of cannabis is illegal and dangerous. Cannabis use can impair driving ability for up to 24 hours after consumption.


  • Employment Impact: Regular cannabis use has been linked to impaired academic achievement, employment difficulties, and lower income.


Conclusion

While many people can enjoy cannabis without significant risk, there is still only limited evidence for therapeutic benefits for certain conditions, and its potential risks should not be underestimated. Users should weigh the benefits against the risks, especially when considering regular or heavy use. If you’re using cannabis, I’d recommend consulting with your healthcare provider to assess whether it’s a safe and appropriate option for your specific health situation. By being informed, you can make choices that protect both your physical and mental well-being.

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