I came across this article on the New York Times website that investigates the claim that you should NOT blow your nose if you have a cold.
Imagine that! Not blowing your nose when you feel all congested and stuffy. It seems very counter intuitive. Are we supposed to walk around with mucous streaming out of our noses when we have a cold. When one feels all wretched because of a cold, I doubt that one would want others to be appalled at them.
However, the article states that blowing the nose results in excess buildup of pressure in the sinuses, in addition to compounding the disease by propelling bacteria and viruses into the sinuses possibly causing further infection.
The conclusion: Blow your nose one nostril at a time and take decongestants according to Dr. Anil Kumar Lalwani, chairman of the department of otolaryngology at the New York University Langone Medical Center.
Essentially, your nose is not a trumpet! Go easy when you blow it :P