Effect of Gefapixant on Cough-related Brain Activity in Patients With Chronic Cough

Inclusion Criteria: * Written informed consent to participate in the study. 18-65 years old; Male or female. * Non-smokers for at least 5 years and have no history of neurological disease or any recent history (over 8 weeks) of acute respiratory infections. * Presence of Refractory Chronic Cough (RCC) or Unexplained Chronic Cough (UCC) for ≥1 year, defined as cough unresponsive to treatment for underlying conditions including reflux disease, asthma and rhinitis. * Presence of cough symptoms as determined by a self-reported cough severity of ≥40mm on 10-point scale on screening. Exclusion Criteria: * Current smokers or recreational drug users. * Women who are pregnant. * People with contraindications to MRI scanning (i.e. metal implants, claustrophobia). * Children and/or young people (ie. \<18 years). * People with an intellectual or mental impairment. * People highly dependent on medical care. * People in existing dependent or unequal relationships with any member of the research team. * People with known allergy to chili (very rare). * Non-English speakers (as English proficiency is required to accurately complete research tasks).