PETRICHOR is a prospective, non-interventional, single-arm, multi-centre study in Germany evaluating real-world clinical and patient-reported outcomes in adults with severe chronic rhinosinusitis with nasal polyps (CRSwNP), whose disease is inadequately controlled with systemic corticosteroids (SCS) and/or surgery. Eligible participants are newly initiated on subcutaneous tezepelumab in routine clinical practice, in accordance with the European Summary of Product Characteristics (SmPC). Treatment decisions are made jointly by patients and their physicians, independent of study enrollment. No additional diagnostic or monitoring procedures are applied; data are collected using epidemiological methods at baseline and during routine clinical visits for up to 104 weeks.