Marijuana and E-Cigs Can Harm the Heart Like Traditional Cigarettes

E-cigarettes and marijuana have similar harmful effects on the heart as tobacco cigarettes, opening the door to abnormal heart rhythms, reports a team of researchers at UC San Francisco.

“We found that cigarettes, e-cigarettes, and marijuana greatly interfere with the electrical activity, structure, and neural regulation of the heart,” said lead author Huiliang Qiu, MD, PhD.

Smoking tobacco leads to several kinds of harmful cardiovascular effects, including increasing the chances of arrhythmias. E-cigarettes and heated tobacco products have become popular because the public perceives them as being less harmful than smoking. Similarly, legal recreational marijuana has become more common in recent years, and is also frequently viewed by the public as being safer than smoking tobacco.

In this study, researchers exposed rats for eight weeks to a single daily session of exposure to Marlboro Red cigarette smoke, aerosol (“vapor”) from the popular e-cigarette JUUL, aerosol from the heated tobacco product IQOS, smoke from marijuana cigarettes, and smoke from modified marijuana that lacks all cannabinoids, compared to just air. The exposures modeled a single session of actual smoking/vaping: the rats inhaled the smoke or aerosol for five seconds twice a minute for five minutes, with clean air in between the smoke inhalations. This was done once per day for five days/week for eight weeks.

During that time, the heart function in the rats exposed to the products got progressively worse and blood pressure increased.

At the end of the study, the researchers conducted various tests to determine electrical and physical properties of the hearts. They found that all the products led to increased scarring in the hearts, a decrease in the number of blood vessels, a change in the type of nerves found in the heart, a reduction in the important ability to vary heart rate and the hearts were more likely to develop arrhythmias.

“It’s notable that all of these tobacco and marijuana products had such similar effects,” said senior author Matthew Springer, PhD. “And what’s really striking is that this was caused by a single realistic smoking/vaping session per day.”

“The bottom line is that e-cigarettes, IQOS, and marijuana cigarettes still involve many of the potential harmful effects of smoking tobacco,” Springer said, “None of these products should be assumed to be a harmless replacement for smoking. In other words, just breathe air.”


Huiliang Qiu, Hao Zhang, Daniel D. Han, Ronak Derakhshandeh, Xiaoyin Wang, Natasha Goyal, Mina Navabzadeh, Poonam Rao, Emily E. Wilson, Leila Mohammadi, Jeffrey E. Olgin, Matthew L. Springer. Increased vulnerability to atrial and ventricular arrhythmias caused by different types of inhaled tobacco or marijuana products. Heart Rhythm, 2022; DOI: 10.1016/j.hrthm.2022.09.021

University of California – San Francisco. “Marijuana and e-cigs can harm the heart like traditional cigarettes, research finds: New study shows these substances may lead to heart disorders.” ScienceDaily. ScienceDaily, 15 November 2022. <>.

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