Marijuana has been around for a long time. There is evidence of marijuana use from the Middle East and Central Asia dating about 2000 years ago. Now that evidence goes even further back. Recently, cannabis seeds were discovered amongst artifacts in a burial mound in Siberia. This discovery has been dated to 2800 years ago, making it the oldest known evidence of marijuana use. Back in our current millennium, marijuana is available for medical use in 41 states. In January 2021, New Jersey became the 24th state to legalize recreational marijuana. It has been estimated that 25% of the people in the US used marijuana in 2022, about 62 million people. Those numbers are only growing. In 2015, about 31% of young adults (ages 19 to 30) and about 16% of mid-life people (ages 35 to 50) used marijuana. In 2025, those numbers increased to 42% of young adults and 30% of older adults. In addition, people are using it regularly. About 29% of the young adults and 20% of mid-life adults report regular use (for comparison 3% of young adults and 7% of mid-life adults report drinking alcohol daily). With all of this marijuana smoking going on, what are the benefits and risks? Marijuana is purported to be useful for a variety of medical issues. Is marijuana a panacea, a cure for multiple ailments? Or is there a monster under the bed, are there hidden dangers?
Marijuana (cannabis) is a plant with psychoactive and medicinal actions. Its two main agents are delta-9-tetrahydrocannabinol (THC) and cannabidol (CBD). What is the efficacy of marijuana in various illnesses? There are a number of conditions where marijuana has been used and the strength of the data of its use varies widely. There is very strong evidence (and an FDA approved indication) for three primary ailments. First, CBD may be used in pediatric seizure disorders. Second, THC is useful for chemotherapy induced nausea and vomiting. Third, marijuana is used as an appetite stimulus in HIV/AIDS related anorexia. There is moderate data for THC/CBD in reducing muscle spasms and pain in multiple sclerosis. There is small to moderate decrease in neuropathic pain (CBD alone offers no relief, slight benefit with combination THC/CBD). Studies do not support marijuana use in the following scenarios. There is low-quality evidence that THC or CBD helps with insomnia, sleep apnea or fibromyalgia. There is no benefit and in fact THC or CBD can worsen anxiety, post traumatic stress disorder (PTSD), depression or psychosis.
How does marijuana affect the cardiovascular system and are there risks? Both THC and CBD have effects on the cardiovascular system. THC activates the sympathetic system resulting in an increase in heart rate, blood pressure and work load on the heart. In addition, it promotes inflammation and blood clotting. CBD lowers heart rate and blood pressure and is anti-inflammatory. There is conflicting data on the association between marijuana and heart disease. The main stumbling block in the research is participants’ honesty in divulging their marijuana use and frequency of use. Despite this, the majority of good quality research does tie marijuana use to heart artery disease. One study found a 29% higher risk for acute coronary events and higher cardiovascular mortality among marijuana users versus nonusers. Another study showed that people who used marijuana daily were 34% more likely to have heart artery disease than those who never smoked marijuana. However, in the same study, monthly marijuana use was not associated with an increase risk. Another study confirmed that daily cannabis use increased the risk for coronary artery disease, heart attack and stroke compared with nondaily use. Lastly a review of 24 studies revealed an association between marijuana use and major adverse cardiac events. On the other hand, a study of US veterans who had established heart disease and who had recently smoked marijuana or had used it in their lifetime did not find an association with heart attack, stroke or cardiac death. In addition, studies have found that cannabis use increases the risk for atrial fibrillation, congestive heart failure and peripheral artery disease.
Is it the marijuana smoke or it is the THC that is causing heart disease? Marijuana smoke contains the same chemicals and fine particulate matter found in tobacco smoke, which contributes to lung, vascular and heart disease. A recent study found that both marijuana smoking and THC edible use were associated with reductions in vascular function compared to nonusers, similar to tobacco smokers. Therefore, THC edible use may not be safer than smoking, pending future research.
It seems that the evidence from high-quality studies doesn’t support the use of marijuana for most medical conditions for which it is promoted, including pain, anxiety and insomnia. There also seems to be substantial cardiac risks and harms with marijuana use. Proceed with caution.
