At the time of sneezing, the air comes out of the human noses, at a speed of 100 meters per hour. Thus, if you cease the air to come out, it can move and attack any other part of the body.
The way, a person sneeze, varies from location to location, maybe between house and business meetings. Sometimes, it is stopped from coming out, as it looks better and more civilized, but, it is harmful for health, as it moves back to the body with 100 meteors per hour speed.
It can attack the ear, with the complete pressure, and can cause a serious damage. It has the ability to puncture the eardrum, which can lead to loss of hearing or even dizziness, that will not be cured easily.
The blood vessels, or other parts in the eyes can get damaged, and can make the diaphragm to suffer, or even can damage it. Ceasing to sneeze can cause a neck injury, and can cause new wounds, for those, who recently had sinus surgery. But, there is a worst case, when it can damage the tissues within the brain, to cause a stroke.
Thus, if you feel like sneezing in public, do not get ashamed of it, because you will have to pay for it, in case of any injury. Instead of stopping the sneeze, you can use a handkerchief on the nose and sneeze, like others do. In case you do not have it, or do not have time to reach it, you can cover the nose or mouth, with your own palm, and shake your hands, when you find it suitable.