Chronic effects
Dental/oral. Smoking marijuana is associated with an increased risk for dental caries, periodontal disease, and oral infections.1 Premalignant oral lesions, such as leukoplakia and erythroplakia, have also been reported. Patient education on the risks and need for proper oral hygiene is vital, as are regular dental examinations.
Respiratory. There are several known pulmonary implications of smoking marijuana, and therefore, this route of administration is not recommended for medicinal use. Respiratory effects of marijuana smoke are similar to those seen with tobacco: cough, dyspnea, sputum production, wheezing, bronchitis, pharyngitis, and hoarseness.4 Increased rates of pneumonia and other respiratory infections have also been identified.6 Research on long-term marijuana smoking has revealed hyperinflation and airway resistance.6 At this time, evidence is inconclusive as to whether smoking marijuana leads to chronic obstructive pulmonary disease.1
Studies have compared the chemical content of tobacco and marijuana and found similar components, including carcinogens, but data regarding concentrations of these chemicals are conflicting.1,4 It is unknown whether vaping (a trending practice in which a device is used to heat the substance prior to inhalation) reduces this risk.4
Unfortunately, data regarding the carcinogenic effects of long-term marijuana smoking are inconclusive; some studies have shown potential protective effects.4-6 Other evidence suggests that the risk is lower in comparison to tobacco smoking.6
Cardiovascular. The effects of marijuana on the cardiovascular system are not fully understood. Known symptoms include tachycardia, peripheral vasodilation, hypotension, and syncope.4 There is some evidence that marijuana use carries an increased risk for angina in patients with previously established heart disease.5 Patients, especially those with known cardiovascular disease, should be educated about these risks.
Reproductive. There are several identified reproductive consequences of marijuana use. Research has found decreased sperm count and gynecomastia in men and impaired ovulation in women.4 Studies on marijuana use in pregnancy consistently reveal low birth weight—this effect is, however, less than that seen with tobacco smoking.5 Other complications or developmental abnormalities may occur, but there is currently a lack of evidence to support further conclusions.
Neurologic. The use of marijuana results in short-term memory loss and other cognitive impairments. There is conflicting evidence as to whether long-term effects remain after cessation.5,6 Because acute intoxication impairs motor skills, it is associated with increased rates of motor vehicle accidents.6 Driving while under the influence of marijuana should be cautioned against.
Psychiatric. Marijuana use is associated with the onset and exacerbation of acute psychosis. However, its role as a causal factor in schizophrenia has not been established.4,10 There is some evidence to suggest that CBD has antipsychotic properties, warranting further research. An amotivational syndrome has also been affiliated with chronic marijuana use; affected individuals exhibit a lack of goal-directed behavior, which may result in work or school dysfunction.10 Several studies have supported an association between marijuana use and risk for depression and anxiety. Due to the extensive risk factors for these disorders, including genetic and environmental, causality has yet to be established.5,6