AbstractHaemophilia nurses in the UK are instrumental in supporting people with haemophilia in self-management, including managing treatment options, recording treatment use and understanding the budgetary impact of prescribing practice. The widespread use of prophylaxis identified haemophilia as a high cost disorder to treat, resulting in a financially successful national tendering process with increased scrutiny of clotting factor use at both individual and haemophilia treatment centre level. The UK tenders, undertaken at a national level every three years, have ensured access to current and new therapies at the most cost-effective price through economies of scale in committing to purchase large volumes from suppliers.In the 2018 tendering round, NovoEight® (NovoNordisk) was added to the prescribing list and other recombinant factors were withdrawn, resulting in changes in prescribing for individual people with haemophilia. This ‘switching’ process is not uncommon in the UK, where national tenders have been in place since 2004. However, the unseen additional workload for nurses, driven by the demands of timely switching to meet product volumes and contracts, has never been captured. During the 2018 switch we interviewed 11 nurses and one operational manager from haemophilia centres across the UK to identify the barriers and facilitators to instigating this change.Ultimately the switching was completed in a timely manner, demonstrating significant cost reductions for factor concentrates. The unseen workload of the nurse – identifying which patients should have their product switched, discussion with and education of patients/families, adjusting prescriptions for home delivery of clotting factor concentrates and stock management and control to avoid waste, and organising the necessary additional clinic visits – was identified and costed based on salary per hour. Nurses remained positive that they were able to undertake this additional role but recognised that, with no specific national guidance regarding product choice, there may have inevitably been differences in approach between treatment centres.