Severe asthma is a disease characterised by respiratory and non-respiratory symptoms. The respiratory symptoms can include breathlessness, wheeze and asthma attacks. The disease can come to dominate patients' lives, impacting their social, working and personal lives, leading to depression, anxiety and feelings of social isolation. There are now 7 different biologic treatments available on the NHS in the UK for severe asthma. These treatments have dramatically changed how severe asthma can be treated. Research has typically focused on the benefits of these drugs from a clinical perspective, e.g., improvements in lung function, blood tests and reduction in frequency of asthma attacks and use of steroid tablets. While these are important outcomes, they do not reflect the experiences of patients receiving these treatments, which can vary greatly. First, not all patients benefit to the same degree. Second for patients who do respond, some respond slower than others. Third while these treatments target respiratory symptoms, some patients report wider benefits, such as reductions in fatigue, depression, ability to engage in family life and other daily activities. Fourth, patients report different side effects when starting these treatments and sometimes for months afterwards, including headaches, fatigue, mental fog and joint pain. These experiences are reported by clinicians and patients, but the extent of these four variations is poorly understood, and potential reasons for them have not been explored. To describe these differences between patients' experiences and begin understanding why they are present, we have co-designed a survey with people who have lived experience of severe asthma who are members of the European Lung Foundation's (ELF) Patient Advisory Group (PAG). This process has resulted in a survey that contains content important to patients and is worded in a way that avoids confusion regarding the meaning of the questions.