Pot inhaled through a vape device produces a
more powerful high — and often with more deleterious side effects — than the
smoked version, a new study finds.
At the same level of THC, the psychoactive
ingredient in marijuana, vaping led to higher blood concentrations of the
chemical than smoking, as well as higher levels of cognitive and psychomotor
impairment and a higher incidence of adverse effects, such as vomiting,
anxiety, hallucinations and feelings of paranoia, according to the report,
published Friday in JAMA
It’s important to understand the impact of
vaping as more and more states legalize cannabis and the drug becomes more
easily accessible, said the study’s lead author, Tory Spindle, a postdoctoral
research fellow at Johns Hopkins School of Medicine. “More people are coming
into cannabis dispensaries and using for the first time in a while or for the
first time ever,” Spindle told NBC News. “They should be aware that vaping will
produce stronger effects. We found there was a fine line sometimes between a
dose that produced the desired effects and one that was too strong.”
The study comes out as more and more Americans
are using pot, including teens. In fact, a recent study found that as many as 1
in 11 are vaping cannabis, while another reported that cannabis has more
deleterious effects on developing brains than alcohol.
To learn more about the impact of vaping
cannabis, Spindle and his colleagues rounded up 17 intermittent pot smokers
whose average age was 27. Most had not used cannabis in a long while; on
average, it had been nearly a year.
All study volunteers completed three
eight-and-a-half-hour sessions during which they smoked marijuana at three
different THC doses (zero milligrams, 10 mg and 25 mg) and three in which they
vaped the drug at the three different doses. The sessions were scheduled to be
a week apart. The zero-milligram dose served as the control in this study.
Once the volunteers had vaped or smoked the
cannabis, their cognitive and motor abilities were tested. They were also asked
to fill out a questionnaire rating items that assessed the extent to which
volunteers felt the following: drug effects; pleasant drug effects; unpleasant
drug effects; sick; heart racing; anxious and/or nervous; relaxed; paranoid;
alert; irritable; vigorous and/or motivated; restless; hungry and/or had the
munchies, sleepy; dry mouth; dry, red, and/or irritated eyes; throat irritation
and/or coughing; difficulty performing routine tasks; memory impairment; and
cravings from cannabis.
At both non-zero doses, the impact of cannabis
was larger when vaped than when smoked, researchers found. But at the higher
dose, vapers experienced more negative side effects. “Two people vomited from
the high dose,” Spindle said. “One actually experienced some audio and visual
hallucinations. Some experienced paranoia as well. So it’s not just about
impairment. The negative effects can be quite unpleasant.”
Spindle suspects that stronger effects are
felt when vaping mainly because none of the material is lost to combustion.
“The difference is most likely due to some destruction of the drug when the
cannabis is burned, which doesn’t occur when it is vaporized,” he said.
Proof that vaping has a stronger impact than
smoking is important, said Dr. Michael Lynch, director of the Pittsburgh Poison
Center at the University of Pittsburgh Medical Center.
“People often create an equivalency between
vaping and smoking, assuming that if you’re using the same amount of the drug
the effects will be similar,” Lynch said in an interview. “I think this helps
inform people who are going to use it medically or recreationally that the
effects aren’t the same and the same dose could lead to more negative or
Lynch is particularly concerned about teens.
“Adolescents are more likely to vape than to smoke,” he said. “Data coming
mostly from nicotine use shows that vaping is a pretty common way teens are
Another worry to keep in mind, Lynch said, is
that as teens start to drive, "they need to understand that these drugs
are intoxicating. We’ve definitely seen rises in drugged-driving-related
injuries and fatalities.”
There are a lot of misconceptions regarding
vaping, said Stan Glantz, a professor of medicine and director of the Center
for Tobacco Control Research and Education at the University of California, San
“There’s an assumption that because you’re not
setting the substance on fire, it’s not as bad,” Glantz said. “That’s turning
out not to be true. In addition to delivering a higher dose of the drug, vaping
produces an aerosol of ultrafine particles that are sent to the lungs and then
the brain. These particles are really small, a 50th to 100th the size of a
hair. They can go right through the lungs and into the blood and from there
into the cells of the body.”
Linda Carroll is a regular health contributor to NBC News. She
is coauthor of "The Concussion Crisis: Anatomy of a Silent Epidemic"
and "Duel for the Crown: Affirmed, Alydar, and Racing's Greatest
Rivalry." She is also a contributor for Reuters Health.