A new analysis of existing studies co-led by a University of Massachusetts Amherst public health researcher finds that nicotine e-cigarettes consistently help adults quit smoking, a conclusion that emerges with striking agreement across nearly a decade of studies.
The "review of reviews," published today in Addiction , examined 14 systematic reviews covering 109 primary studies conducted between 2014 and 2023. Across 21 separate meta-analyses, every pooled estimate pointed in the same direction: Smokers using nicotine e-cigarettes were more likely to quit than those using most other methods.
The review found that nicotine e-cigarettes are associated with quit rates approximately 20% to 40% higher than traditional nicotine replacement therapies, such as patches or gum, for smoking cessation lasting at least six months. Compared with non-nicotine e-cigarettes or placebo devices, nicotine e-cigarettes performed even better, with quit rates at least 46% higher.
"We set out to determine if scientists agree on whether nicotine e-cigarettes help people quit smoking," says senior author Jamie Hartmann-Boyce , assistant professor of health policy and management in the School of Public Health and Health Sciences at UMass Amherst. "Based on the consistency of the findings here, it's clear that they do."
However, she cautions that this doesn't necessarily mean e-cigarettes are the best option to quit smoking, or that they will work for everyone. Vaping also comes with health risks, but those risks pale in comparison to the dangers of smoking.
"It's not just the person who smokes who is affected by their smoking," Hartmann-Boyce notes. "It's the people around them who are affected by secondhand smoke, and secondhand vaping is nowhere near as harmful as secondhand smoking either."
The effectiveness of e-cigarettes may stem from more than just nicotine delivery.
"If you look at neuro-imaging studies, the addiction often isn't just to the nicotine," she explains. "There are the sensory cues around it that really feed into those addiction pathways. Vaping fulfills some of those cues in a way that a patch doesn't"—including the throat hit, the hand-to-mouth motion and the visible exhale.
Many of those same features, Hartmann-Boyce points out, are why youth uptake remains a serious concern.
"The primary concern about e-cigarettes is their use among people who don't smoke and wouldn't have otherwise smoked," she says. "That doesn't mean these devices don't help people quit smoking."
While e-cigarettes with nicotine may prove more effective than traditional nicotine replacement therapies, it remains unclear if they are as effective a class of drugs known as nicotine receptor partial agonists, which are available only via prescription. Varenicline, marketed as Chantix in the U.S., can lessen smoking satisfaction and reduce withdrawal cravings.
"We don't have enough studies to compare these drugs to nicotine e-cigarettes to say whether one is better than the other for helping people quit smoking," Hartmann-Boyce says.
She hopes the new analysis will provide some clarity about vaping. While the evidence that nicotine e-cigarettes can help quit smoking has never been stronger, public perception of vaping has soured, amid lung injuries associated with a certain additive in some THC-vaping products and marketing campaigns targeting young people .
When half of all lifelong daily smokers die from the habit, Hartmann-Boyce insists that evidence matters.
"We know e-cigarettes are not risk free, but they are so much less harmful than smoking," she says.
