Lay summary
Many people who smoke tobacco also use other nicotine products, like vapes, but want support to stop or reduce use of all nicotine products, especially the most harmful ones. However, we don't have any evidence on the best forms of treatment and support to assist them in doing so. To identify the most effective treatments for supporting people dependent on nicotine, regardless of the nicotine source, we will invite people who smoke cigarettes and use other forms of nicotine (vapes, heated tobacco, or pouches) to take part in a trial comparing two different treatments: cytisine or tapering nicotine. Everyone will be randomly allocated to one of the treatments and have access to behavioural support. The focus is on preventing disease by identifying cost-effective treatments, ones that support people to be both tobacco- and nicotine-free, financially independent from nicotine, improve their productivity and the quality and length of their lives.