Key messages
Using a combination of nicotine patches together with another type of nicotine replacement therapy (NRT) (such as gum or lozenge) is more likely to help people quit smoking than if they used one type of NRT alone. We also found that people who smoke have the same chance of quitting successfully whether they use a nicotine patch or another type of NRT, such as gum, lozenge or nasal spray.
More high-quality studies on different NRT patch doses, durations of NRT use, types of fast-acting NRT, and NRT use prior to quit day are needed to know which treatments work best to help people quit smoking. These studies should report safety outcomes and withdrawals due to treatment.
What is nicotine replacement therapy?
Nicotine replacement therapy (NRT) is a medicine that delivers nicotine to the brain. It is available as skin patches, chewing gum, nasal and oral sprays, inhalers, lozenges and tablets. The aim of NRT is to replace the nicotine that people who smoke usually get from cigarettes, so the urge to smoke is reduced and they can stop smoking completely. We know that NRT improves a person's chances of stopping smoking, and that people use it to quit.
What did we want to find out?
NRT can be taken in many different forms, in different doses and for varying amounts of time. Some people start using NRT before they quit, while other people wait until quit day. This review looks at the different forms, doses, durations and schedules of NRT used to help people quit smoking, so we can better understand which of these work best to help people quit smoking for six months or longer. We also wanted to find out if any of these treatments were associated with cardiac (heart-related) or serious unwanted effects, and if anyone stopped participating in a study due to the NRT treatment they were advised to use.
What did we do?
We searched for studies that looked at the use of NRT to help people quit smoking and that followed people up for at least six months.
What we found
We found 68 completed studies conducted in 43,327 participants. Most participants were adults who wanted to quit smoking.
Main results
People who smoke have the same chances of quitting successfully whether they use a nicotine patch to quit or another type of NRT, such as gum, lozenge or nasal spray. Using nicotine patches together with another type of NRT (such as gum or lozenge) made it 17% to 37% more likely that a person would successfully stop smoking than if they used one type of NRT alone.
People who used higher-dose nicotine patches (25 mg patches worn for 16 hours, or 21 mg patches worn for 24 hours) were more likely to quit smoking compared to those using lower-dose patches (15 mg patches worn for 16 hours or 14 mg patches worn for 24 hours). However, there was not any clear evidence to suggest that people using 42 mg or 44 mg patches were more likely to quit than people using 21 mg or 22 mg (24-hour) patches.
Starting to use NRT before a quit day may help more people to quit than only using it after a quit day, but more evidence is needed to strengthen this conclusion.
We also looked at how long NRT should be used for, whether NRT should be used on a schedule or on demand as craved, and whether more people stop smoking when NRT is provided for free versus if they have to pay for it. More research is needed to answer these questions.
Most studies did not look at the safety of NRT. Where studies did look at safety, they found that very few people experienced negative effects.
How reliable are these results?
There is high-certainty evidence that:
- combination NRT works better than a single form of NRT; and
- there is no difference in effect between different types of NRT (such as gum or patch).
This means that future research is very unlikely to change our conclusions. This is because the evidence is based on many participants and on well-conducted studies.
However, the certainty of the evidence was moderate, low or very low for all the other questions we considered. This means that our findings may change as new research is carried out. In most cases, this is because there were not enough studies, there were problems with the design of studies that do exist, and/or these studies were too small.
In terms of the safety of different ways of using NRT, we rated the evidence for this outcome to be of low or very low certainty because many studies did not report on safety. Large studies covered in a separate review show high-certainty evidence that NRT is safe to use for quitting smoking.
How up to date is this evidence?
This review updates our previous review. The evidence is up to date to April 2022.