ABSTRACT
It is recommended that decongestant nasal drops should not be used for more than 10 days. However, overuse or misuse of these medications occurs commonly, which may lead to injurious effects on the nasal mucosa. Ten male rats receiving either oxymetazoline or saline nasal drops were killed after 8 weeks. Respiratory and olfactory nasal mucosae were dissected and processed for light and electron microscopic study. Nasal respiratory mucosa showed multi-focal areas of proliferation, metaplasia and degeneration accompanied by ciliary loss. The olfactory mucosa revealed disorganization, degenerative changes with atypical nuclei. Prolonged administration of oxymetazoline topical nasal drops can result in structural and functional alterations in the rat nasal respiratory and olfactory mucosae, presumably due to the combination of the chronic hypoxic effect of the reduced blood flow and the impairment of the mucociliary clearance