Doxycycline: lights and shadows of a mysterious treatment for chronic rhinosinusitis.

Purpose of review: Chronic rhinosinusitis (CRS) is a diverse condition, including different underlying pathophysiologies. Tailoring the treatment for CRS depends on the individual's specific endotype and phenotype rather than using a universal approach. The emergence of biologics in recent years has raised questions about the role of antibiotics, particularly doxycycline, in CRS management. Insights from existing research on the mechanisms and appropriate use of doxycycline therapy may guide physicians in selecting the right treatment target.

Recent findings: CRS with nasal polyps (CRSwNP) is frequently associated with type 2 inflammation and characterized by tissue remodeling process that can result in recalcitrant condition. Doxycycline therapy (100 mg daily) improves CRSwNP by exerting antitissue remodeling effects through matrix metalloproteinase inhibition. Doxycycline seems to provide benefits when used alongside adequate medicine treatment.

Summary: Current evidence on the use of doxycycline therapy is limited to a small number of high-quality studies. Further research is needed to explore the duration and factors of success of doxycycline in treating CRS. Like other antibiotics, doxycycline has limitations related to side effects and the potential for antibiotic resistance. Therefore, treatment decisions should be made with caution, especially when doxycycline is used in combination with other pharmacologic therapies.