This guideline covers support to stop smoking for everyone aged 12 and over, and help to reduce people's harm from smoking if they are not ready to stop in one go. It also covers ways to prevent children, young people and young adults aged 24 and under from taking up smoking. The guideline brings together and updates all NICE's previous guidelines on using tobacco, including smokeless tobacco. It covers nicotine replacement therapy and e-cigarettes to help people stop smoking or reduce their harm from smoking. It does not cover using tobacco products such as ‘heat not burn’ tobacco. In November 2021, varenicline was unavailable in the UK. See the Medicines and Healthcare products Regulatory Agency (MHRA) alert on varenicline.