What is a blocked nose?

Factual Questions
#1

I’ve got a cold sniffcoughachoo and I was thinking about some of my past colds, and their severity and discomfort…

And I started to wonder just what it is that’s blocking a ‘blocked nose’. Is it mucus? Is it a narrowed nasal passage? Is it a combination? Or something else?

Why does teh aroma of eucalyptus (and similar) seem to temporarily alleviate the blockage? And why does blowing your nose expel the build up of mucus but not necessarily unblock the nostril?

Icky questions, but I just gotta gotta know!

Ta…

#2

There’s some mucus buildup, sure, but most of it is swelling of the nasal tissues. This is a sign that your immune system is doing its job. I don’t know about eucalyptus, but nasal decongestants work by reducing the swelling, so you can breathe. I love that stuff. Dave Barry once rightly referred to it as the best medical product available - it claims to relieve nasal congestion, and, by golly, it actually relieves nasal congestion!