What are e-cigarettes?

Electronic cigarettes (electronic cigarettes) are usually hand-held devices that heat liquids containing nicotine and fragrances. E-cigarettes allow you to breathe nicotine in steam, not smoke. Because tobacco does not burn, e-cigarette users are not exposed to the same levels of chemicals that can cause disease in ordinary smokers.

The use of e-cigarettes is commonly known as “vaping”. Many people use e-cigarettes to stop smoking. In this study, we focus primarily on nicotine e-cigarettes.

Why we did this Cochrane review

Quitting smoking reduces your risk of lung cancer, heart attack and many other diseases. Many people have difficulty quitting smoking. We wanted to learn that the use of e-cigarettes can help people to quit smoking, and people who use it for this purpose are exposed to any undesirable effects.

What did we do?

We looked for research on the use of e-cigarettes to help people quit smoking.

We looked at randomized controlled trials in which people received randomized treatment. This type of research usually provides the most reliable evidence of the effectiveness of treatment. We also looked at studies where everyone received e-cigarette treatment.

It was interesting to learn from us:

路 How many people have stopped smoking for at least six months; and
路 How many people have been reported to have undesirable effects after at least one week of use.

Search history: We have included evidence published before May 1, 2021.

What we found

We found 61 studies on 16,759 adults who smoked. The study compared e-cigarettes with:

路 Nicotine replacement therapy such as patches or chewing gum;

路 Varenicline (a drug that helps people stop smoking);

路 E-cigarettes without nicotine;

路 Other types of nicotine-containing e-cigarettes (eg pod devices, newer devices);

路 Behavioral support such as counseling or advice; or

路 No support to stop smoking.

The largest number of studies was conducted in the United States (26 studies), the United Kingdom (11) and Italy (7).

What are the results of our review?

More people than nicotine replacement therapy (4 studies, 1924 people) or nicotine-free e-cigarettes (5 studies, 1447 people) quit smoking for at least six months using nicotine e-cigarettes.

Nicotine e-cigarettes can help more people quit smoking than any support or behavioral support (6 studies, 2886 people).

9-14 out of every 100 people who use nicotine e-cigarettes to quit smoking can successfully quit, while only 6 out of 100 people who use nicotine replacement therapy, 7 out of 100 people who use nicotine-free e-cigarettes or 100 smokers four just don鈥檛 have support or behavioral support.

There is no support or behavioral support between the use of nicotine e-cigarettes compared to nicotine replacement therapy and how many side effects occur, we are uncertain. There was some evidence that non-serious side effects were more common in groups receiving nicotine e-cigarettes than with no support or behavioral support. A small number of similar adverse events, including serious adverse events, have been reported for other comparisons. There is probably no difference in the number of non-serious side effects experienced by people who use nicotine e-cigarettes compared to nicotine-free e-cigarettes.

The most common side effects of nicotine e-cigarettes are throat or mouth irritation, headache, cough, and illness. As people continue to use nicotine e-cigarettes, these effects have diminished over time.

How reliable are these results?

Our results are based on a small number of studies, and in some cases the data varied widely.

We are moderately convinced that nicotine e-cigarettes help people quit smoking more than nicotine replacement therapy or nicotine-free e-cigarettes. Additional research is still needed to confirm this.

Studies comparing nicotine e-cigarettes with non-behavioral or non-behavioral ones showed higher withdrawal rates in people who used nicotine e-cigarettes, but the study provided less specific information due to design problems.

Most of our conclusions about undesirable effects may change as more evidence becomes available.

Key messages

Nicotine e-cigarettes probably help people quit smoking for at least six months. They probably work better than nicotine replacement therapy and nicotine-free e-cigarettes.

They may work better than unsupported or behavioral support alone and may not be associated with serious undesirable effects.

However, we need more evidence to be convinced of the effects of e-cigarettes, especially the effects of new types of e-cigarettes that carry nicotine better than old e-cigarettes.