The FDA has approved the drug dupilumab (Dupixent) as the first and only treatment for allergic fungal rhinosinusitis (AFRS) in adults and children 6 years of age and older with a history of sinus surgery.[1][2][3] The approval took place under priority review and expands the indications of Dupixent to sinus-nasal diseases.[1][2][3] AFRS is a rare type of chronic sinusitis caused by an allergic reaction to fungi, with the production of thick, peanut butter-like mucus.[3] It affects up to 8% of people with chronic sinusitis and nasal polyps, is more common in warm and humid areas, and typically begins in the teenage years.[3] The efficacy of dupilumab was confirmed in a 52-week phase III study, where it significantly improved sinus opacification on CT (Lund-Mackay score), polyp size, nasal congestion, and olfaction compared to placebo.[1][2][3] The drug reduced the need for systemic corticosteroids and sinus surgery, as well as sinus bone erosion.[3] The most common side effects include injection site reactions, eosinophilia, insomnia, toothache, gastritis, and joint pain.[3]