Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterised by relapsing and remitting mucosal inflammation of the colon. Despite primarily affecting the gastrointestinal tract, UC has various extraintestinal manifestations that often affect other organs and systems. Although pulmonary involvement is uncommon, organising pneumonia (OP), which affects the lung parenchyma, is one of the potential extraintestinal manifestations of UC. We report a case of OP in a 35-year-old male with a longstanding history of UC, well-medicated with sulfasalazine (SSZ). He presented to the emergency department (ED) with complaints of fatigue, coughing, myalgia, thoracalgia and dyspnoea. A chest X-ray showed parenchymal infiltrates and computed tomography revealed bilateral consolidation. Under a preliminary diagnosis of atypical pneumonia, he was treated with an empirical broad-spectrum antimicrobial agent, which did not lead to any clinical, laboratory or imaging improvement. Furthermore, the diagnostic work-up excluded any malignancy or infectious cause. A probable diagnostic hypothesis was OP as an extraintestinal manifestation of UC or as an adverse effect of SSZ therapy. Hence, SSZ was discontinued, and he was successfully treated with corticosteroids, exhibiting significant improvements and recovering completely during the follow-up period. Despite lung involvement in UC being rare, we present this case to emphasise the importance of a thorough differential diagnosis when treating acute respiratory illness in patients with UC, including extraintestinal manifestations of UC, especially OP, even during a period of remission. We also emphasise the importance of early initiation of corticosteroid therapy to prevent major complications and promote recovery.