Background Massachusetts was the first to implement a state-wide menthol cigarette sales restriction in the USA. Following its implementation in June 2020, evidence showed declines in cigarette sales in Massachusetts; however, changes in nicotine replacement therapy (NRT) product sales are unknown.

Methods This cohort study analysed NRT products sold by US-based retailers available in 26 states from the Nielsen Retail Scanner Data. Outcomes were state-level 4-week aggregate sales of gum, lozenge and patch NRT products converted into pieces per 1000 adults (aged ≥18 years) who smoke cigarettes based on smoking rates from the Behavioral Risk Factor Surveillance System and corresponding population from the US Census Bureau. We used a difference-in-differences method to compare changes in NRT product sales in Massachusetts before (1 January 2017 to 13 June 2020) and after (14 June 2020 to 4 December 2021) the policy with sales in 25 states.

Results The analysis included 1664 observations for each NRT product, with 1170 from before and 494 from after the policy change. The 4-week NRT product sales per 1000 adults who smoke cigarettes in Massachusetts compared with the comparison states increased for gums by 643.11 (95% CI 365.33 to 920.89; p<0.001) pieces or 12.9% and for lozenges by 436.97 (95% CI 292.88 to 581.06; p<0.001) pieces or 17.9% but no statistically significant change in patches after implementing the policy.

Conclusion The increases in sales of gum and lozenge NRT products in Massachusetts after implementing the policy suggest that a nationwide ban on menthol cigarettes can increase NRT product use; therefore, interventions are needed to strengthen cessation support for adults who smoke cigarettes but intend to quit.