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Am Fam Physician. 2016;93(6):492

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Clinical Question

Are electronic cigarettes (e-cigarettes) effective for smoking cessation in adults?

Evidence-Based Answer

Nicotine-containing e-cigarettes may be more effective than placebo devices for smoking cessation. They may also aid in smoking reduction, but the quality of available evidence is low. (Strength of Recommendation [SOR]: B, based on a systematic review.) Little is known about their safety.

A systematic review pooled two randomized controlled trials (RCTs) and found six-month quit rates of 9% for e-cigarettes compared with 4% for placebo (N = 662; relative risk [RR] = 2.29; 95% confidence interval [CI], 1.05 to 4.96).1 The number of participants who reported reducing their cigarette consumption by at least 50% was 36% in the nicotine-containing e-cigarette group compared with 27% in the placebo group (N = 612; RR = 1.31; 95% CI, 1.02 to 1.68).

A double-blind RCT enrolled 362 healthy adults who desired to quit smoking.2 Their average age was 43 years, 62% were female, and they had a smoking history of at least 10 cigarettes per day for at least one year. The study compared six-month smoking cessation rates in those who used a nicotine-containing e-cigarette vs. a non–nicotine-containing placebo e-cigarette. There was no significant difference in quit rates between groups (7.3% vs. 4.1% in the placebo group; RR = 1.8; 95% CI, 0.54 to 5.8). However, because quit rates were lower than expected, the study was underpowered to detect a difference between groups. The time to relapse was not significantly longer in the nicotine group (35 vs. 12 days in the placebo group; P = .09). There was no difference in the number of patients who decreased their daily cigarette use (P = .08). The rate of adverse events was similar.

A double-blind RCT enrolled 300 healthy middle-aged adults (63% male) who smoked more than 10 cigarettes per day for at least five years and who did not desire to quit.3 Smoking cessation rates were compared between three groups: two received different doses of nicotine-containing e-cigarettes, and the third received a non–nicotine-containing e-cigarette. There was a significant reduction in number of cigarettes smoked per day in all three groups (19, 21, and 22 at study beginning vs. 12, 14, and 12 at study conclusion; P < .001 for before-after comparison within each group). However, there were no differences at 24 or 52 weeks. There was no significant difference in quit rates at 52 weeks (13% vs. 9% vs. 4%; P = .24).

The U.S. Food and Drug Administration is reviewing the regulatory status of e-cigarettes. In 2015, it issued warning letters to three major e-cigarette companies for violations, including unsubstantiated claims and violating the Federal Food, Drug, and Cosmetic Act.4

Copyright Family Physicians Inquiries Network. Used with permission.

Help Desk Answers provides answers to questions submitted by practicing family physicians to the Family Physicians Inquiries Network (FPIN). Members of the network select questions based on their relevance to family medicine. Answers are drawn from an approved set of evidence-based resources and undergo peer review. The strength of recommendations and the level of evidence for individual studies are rated using criteria developed by the Evidence-Based Medicine Working Group (

The complete database of evidence-based questions and answers is copyrighted by FPIN. If interested in submitting questions or writing answers for this series, go to or email:

This series is coordinated by John E. Delzell Jr., MD, MSPH, associate medical editor.

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