A stuffy nose is no picnic. It usually affects your breathing and is generally uncomfortable to say the least. When stuffy noses that accompany colds occur, the blood vessels expand, the mucus membranes become congested (full of excess blood), and the nose becomes stuffy, or blocked.
Once the cold virus gets into the nose, histamine is released and that increases the blood flow to the nose. Then the nasal tissues begin to swell up and that stimulates the nasal membranes to produce excessive amounts of mucus.
You can treat a stuffy nose with decongestants, nose drops or sprays.
Sneezing is caused by the irritation of the soft lining of the nose or throat. When you sneeze you inhale air, then the the larynx closes so that air pressure in the lungs is increased, then suddenly the larynx reopens and sends a rush of air out through your nose and mouth.
Treating the sneeze can be counterproductive since it is the body's attempt to clear away offending irritants associated with your cold. The best way to prevent sneezing is to remove the irritants, so gentle nose blowing helps. For sneezing associated with allergies, antihistamines may do the trick, but they have no place in the treatment of colds.