Mesalazine induced interstitial pneumonitis in the COVID era.

Mesalazine is the most widely used aminosalicylate for induction and maintenance of remission in patients with mild-to-moderate ulcerative colitis (UC). Drug-induced hypersensitivity pneumonitis is considered very rare (<1/10.000 patients). Due to its rarity and the scarce cases reported, mesalazine-induced lung injury needs to be highly suspected in a patient with onset of respiratory symptoms and UC under treatment with salicylates. It should make the clinician formulate a differential diagnosis that includes not only infections (tuberculosis, bacterial...) or the inflammatory bowel disease itself, but also the current coronavirus disease 2019 (COVID-19) since their clinical and radiological manifestations may be very similar.