"Suppressing a sneeze can be harmful, particularly to your ears...
Studies have found that the air expelled during a sneeze travels at an
amazing 100 miles per hour, and spews out up to 5,000 droplets, which
may be propelled up to 12 feet in a single sneeze.... By clamping your
mouth closed an pinching your nose shut, you force the "sneeze" into
the eustachian tube (which connects the back of the throat to the
middle ear) and then to your eardrum. Sneeze strong enough, and you
could rupture an eardrum, causing acute pain, infection, bleeding, and
even hearing loss."