The aim of this study was to investigate whether long-term use of oxym
etazoline induces a rebound swelling of the nasal mucosa and whether t
he decongestion effect is altered during medication. Eight healthy vol
unteers had oxymetazoline nasal spray (0.5 mg/ml; 0.1 ml in each nostr
il, three times daily) for 30 days and registrations of the mucosal su
rface positions were made using rhinostereometry. Compared to the regi
strations before the start of medication, no rebound swelling was regi
stered after 10 days. After 30 days, however, a rebound swelling was r
egistered in all subjects (p < 0.001). All of them, then, also reporte
d nasal stuffiness. The decongested position of the nasal mucosa after
one single dose of oxymetazoline was the same in the whole study. It
is concluded that rhinitis medicamentosa develops after a relatively s
hort time on oxymetazoline, even in healthy volunteers, and that the s
welling probably is due to a vasodilatation rather than an edema. The
study supports the recommendation that the drug should not be used ove
r periods >10 days.