Nonpsychotic Cannabinoids in Hypertension: Benefits and Harms

With some 200 million users globally, marijuana has been both pilloried and extolled for its effects on cardiovascular function.¹ After tobacco and alcohol, cannabis, the active ingredient in marijuana, is the most frequently used psychoactive substance.² Early signals from human and animal studies have found that the vasodilation properties of cannabinoids may show promise in arterial, pulmonary, and portal hypertension.¹ While cannabinoids may benefit hypertension, recent studies have shown that one of the most consistent changes in humans who use cannabis — orally, intravenously, or by smoking — is tachycardia.¹

Blood Pressure Changes With Cannabis Use

Cannabinoids exert different effects on blood pressure depending on the route of administration and the frequency of use.¹ A National Health and Nutrition Examination Survey study of more than 12,000 adults found that when compared with never users, cannabis users had higher systolic, but not diastolic, blood pressure. The researchers noted that for daily cannabis users, the increase in systolic blood pressure was a modest 3 mm Hg, which may be difficult to discern in clinical practice.³

Another study that examined the effects of the non-psychoactive cannabidiol (CBD) showed that CBD decreased blood pressure.⁴ In a small, albeit double-blind, study, Khalid Jadoon, MD, from the Division of Medical Sciences & Graduate Entry Medicine at the University of Nottingham, Royal Derby Hospital Centre in the United Kingdom, and colleagues randomly assigned 9 healthy men (mean age, 23.7±3.2 years) to 600 mg CBD or placebo. Although CBD increased heart rate (+10 beats per minute [bpm]; P <.01), it also lowered systolic blood pressure by –6 mm Hg; (P <.05) and stroke volume (–8 mL; P<.05).⁴ CBD also lowered blood pressure in participants who were exposed to cold stress and isometric exercise.⁴

Tracking Cannabis’ Deleterious Effects

While 42 states and the District of Columbia have legalized the use of marijuana for medical or recreational purposes, the evidence of its alleged safety has not kept pace.² The Drug Enforcement Administration still classifies marijuana as a schedule I substance, with high potential for abuse like the addictiveness of heroin.²

Amitoj Singh, a cardiology fellow in the Department of Cardiology at St. Luke’s University Health Network in Bethlehem, Pennsylvania, and colleagues found that if the United States were to keep a registry of cannabis-related emergency department visits, such as France’s Addictovigilance Network, clinicians and policymakers would take a more cautious approach to the adoption of cannabis for medical and recreational uses.²

For example, the French registry found that of cannabis-related visits, 44% were for neurologic events and 2% were cardiovascular in nature. Ischemic stroke was the top reason for emergency visits in cannabis users. From 2006 to 2010, cardiovascular deaths in France related to cannabis increased by 25%.² The United States Nationwide Inpatient Sample data corroborates this bleak trend: cannabis users aged 25 to 34 years were more than twice as likely to have a stroke compared with nonusers.²