There are many “home” remedies for clearing nasal congestion and sinusitis through cleaning the nasal passages, usually involving passing a saline solution through them, e.g.
A recent Cochrane review, Nasal saline irrigations for the symptoms of chronic rhinosinusitis, supports use of this technique originating from an ancient Ayurvedic practice. Read the full story at the Science-based Medicine blog. Do take note of the caution that this is likely only to be beneficial in moderation.
Yes, yes, I only put this up to show the photo. It’s fetching, arresting, isn’t it?!
I want to make clear that the reason this ancient practice can be considered valid is that it has been tested, not because it’s “ancient wisdom” or some equally fuzzy notion!
UPDATE: If you really must try this (it’s a bit of a dubious remedy), best to use sterile water or sterile saline solution, and not tap water, lest you end up like this Seattle woman who died after getting a brain amoeba infection from the water she squirted up her nose.