A stuffy nose can be pretty annoying. Most people think that a stuffy nose is a result of too much mucus accumulating in the nasal passages, but in fact, a clogged nose is caused by inflamed blood vessels in the sinuses.
These inflamed vessels are often triggered by colds, the flu, various allergies, or some kind of sinus infection.
Nasal congestion can be the result of anything that irritates the nasal passages, including various irritants such as tobacco smoke or aggressive fumes. Acute sinusitis is a common cause for a stuffed nose.
If you have only one side of the nose clogged often, this can be a result of a nasal polyp. It is a sac-like noncancerous growth inside the nose that clogs the airway passages. A deviated nasal septum (when the wall between the nostrils is leaning more to one side) can be the cause for nasal congestion, and it can be fixed only by an operation.