Sometimes when the nerve endings in your nose are irritated, they triiger reflexive intake of air, which you then expel at speeds of more than 100 mph. But if you fight a sneeze, you divert that explosion of airback into your head. And that can cause trouble.

1. Sinus Infection

The air could squeeze up through the sinus ostia, openings that allow mucus to drain from your sinuses into your nose. As a result bacteria in your nose may be propelled into your maxillary(cheeks), frontal (forehead), or ethmoidal (between the eyes) sinuses. The trauma of forcing air into your sinusescan cause swelling that blocks the ostia, trapping bacteria inside and causing a sinus infection.

Material provided courtesy of Mens Health Magazine, January 2009.