Proponents of oil of oregano claim it can treat a variety of illnesses, including sinus disorders. Like many spices, oregano does have some antibacterial and antifungal properties — making it at least plausible that it might help or prevent some sinus problems caused by bacteria and fungi.

Unfortunately, there have been no published trials that have looked at oil of oregano specifically for this use. For this reason, it isn't known what role, if any, oil of oregano plays in treating or preventing sinusitis.