Brexit has direct and indirect negative health consequences, whether from economic damage or from the political paralysis and distraction from public health that it has created. Brexit is a public health problem in its own right, as other literature has shown—but, we argue, it is also a symptom of deeper problems in the governance of the United Kingdom. In particular, the combination of executive dominance, partisanship and opacity that give rise to the constitutional casualism of the Brexit decisions has already affected public health policy and will continue to do so unless addressed.