This briefing summarises the current evidence on the health effects of nicotine and outlines the key implications for policymaking. It has been produced by ASH with input from Prof Ann McNeill, King’s College London; Prof Jamie Brown and Prof Lion Shahab, University College London; Prof Nick Hopkinson and Prof Alan Boobis, Imperial College London; Prof Sanjay Agrawal, Chair, Royal College of Physicians Tobacco Advisory Group; Prof Jacob George, University of Dundee; Dr Jasmine Khouja, University of Bath; and Dr Andy McEwen, Chief Executive, National Centre for Smoking Cessation and Training.