NUCALA, generically known as mepolizumab, is a prescription medication designed for the treatment of severe eosinophilic asthma in patients aged 6 years and older, chronic rhinosinusitis with nasal polyps in adults, and eosinophilic granulomatosis with polyangiitis in adults. As a monoclonal antibody, NUCALA specifically targets and inhibits interleukin-5 (IL-5), a key cytokine involved in the growth, activation, and survival of eosinophils, which are a type of white blood cell implicated in the pathogenesis of these conditions. By reducing the number of eosinophils, NUCALA helps to decrease inflammation and reduce the frequency of exacerbations or flare-ups, leading to improved control of symptoms. It is administered through subcutaneous injection, typically once every four weeks, under the guidance of a healthcare professional.