Background: Tobacco smoking rates in alcohol and other drug (AOD) treatment settings is much higher than in the general Australian population. As a result, people seeking treatment for AOD use experience a greater tobacco-related burden of illness. Attempts to reduce smoking rates in AOD treatment consumers have failed to identify smoking cessation strategies with long term effectiveness. The primary aim of this study is to examine the effectiveness of nicotine vaporised products (NVPs) or nicotine replacement therapy (NRT)on self-reported 6 months continuous abstinence at the 9-month follow-up (6 months following end-of 12 weeks of nicotine treatment) for people leaving smoke-free residential withdrawal treatment. Both groups will also receive Quitline telephone counselling. Secondary outcomes and process measures will also be collected. Methods: A two-arm, single-blinded, parallel-group randomised trial with a 6-month post-intervention follow-up (9 months following baseline) will be conducted. The setting is five residential and inpatient government-funded AOD withdrawal units across three cities in three states of Australia (New South Wales, Queensland, Victoria). Participants will be service users aged 18 years or over who smoked at least 10 cigarettes per day, interested in quitting in the next 30 days and have capacity to give informed consent. Research assistants will recruit participants during intake, who then complete a baseline survey, will be randomised to a condition, and receive their first Quitline call during AOD treatment. At discharge, all participants receive a discharge pack containing either NVPs or NRT, depending on condition allocation. Discussion: This is the first study we know of that will be testing intervening with a tobacco smoking cessation approach during the transition phase from AOD treatment to community. From a public health perspective, this approach has the potential to have tremendous reach into a priority population for smoking cessation. Trial registration: Australian and New Zealand Clinical Trials Registry (ACTRN12619001787178)

The authors have declared no competing interest.

ACTRN12619001787178

This study is funded by an Australian National Health and Medical Research Council (NHMRC) Project Grant (GNT1160245).

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Ethical approval for this study has been obtained from Hunter New England Area Health Service (REGIS: 2019/ETH10554) and the University of Newcastle Human Research Ethics Committee (H-2019-0358)

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Data is currently being collected and may be available upon reasonable request to the authors