Mike: Hello, I'm Mike Clarke, podcast editor for the Cochrane Library. The Cochrane Tobacco Addiction Group has produced many reviews of the role of nicotine replacement therapy in smoking cessation and, in June 2023, they updated their review of different doses, durations and modes of delivery. Here’s first author, Annika Theodoulou from the Centre for Evidence-based Medicine at the University of Oxford in the UK to tell us about the latest findings.

Annika: Nicotine replacement therapy, or NRT for short, aims to replace nicotine from cigarettes when someone attempts to quit smoking. This helps to reduce cravings and withdrawal symptoms, thereby easing the transition from cigarette smoking to complete abstinence. NRT is available in many different forms such as skin patches, chewing gum and lozenges, and can be taken in different doses and for varying amounts of time. Some people start using NRT before they quit smoking, while others wait until their target quit day.
Although there is high‐certainty evidence that NRT is effective in helping people quit smoking, the impact of different forms, doses, durations of treatment or timing of use is less clear. Our review aims to help with this by providing a better understanding of which forms, doses, durations and schedules of NRT 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 or serious unwanted effects, and if anyone stopped participating in a study because of the NRT treatment they were advised to use.
We identified five new studies for this update, bringing the total to 68 completed studies, conducted with more than 43,000 people who wanted to quit smoking.
Overall, we found high-certainty evidence that people using a combination of nicotine patches together with another type of NRT (such as gum or lozenge) were 17 to 37% more likely to successfully stop smoking than if they used one type of NRT alone. However, we also found that people 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.
We found moderate‐certainty evidence, limited by imprecision, that 42 or 44 mg patches are as effective as 21 or 22 mg patches, and that 21 mg patches are more effective than the lower dose 14 mg patches. We also found some evidence that ‘preloading’ with NRT, that is, starting to use the NRT before quit day, may help more people to quit than starting NRT on the quit day itself, but more evidence is needed to strengthen these conclusions.
We found no clear evidence of differences based on the duration of nicotine patch use; duration of combination NRT use; or fast‐acting NRT type. Evidence for the comparative safety and tolerability of different types of NRT use was also limited, although large studies covered in a separate Cochrane review do show high‐certainty evidence that NRT is safe to use for quitting smoking.
In conclusion, although we have found some potentially important differences in the effects of different types of NRT, more high‐quality studies on different NRT patch doses, durations of NRT use, types of fast‐acting NRT, and NRT use before quit day are needed to know which treatments work best to help people quit smoking. It will also be important for these studies to report safety outcomes and withdrawals due to treatment.

Mike: If you would like to look at this large collection of evidence on nicotine replacement therapy in more detail, and to watch for the next update as more studies become available, a simple search for 'doses of NRT' on Cochrane Library dot com will show you a link to the review.