You've probably heard the urban legend about what happens if you sneeze with your eyes open.
Well, you'll be pleased to have it confirmed that your eyeballs do not pop out of your sockets like champagne corks. The air spaces in the nose and throat aren't connected to anything behind the eye, meaning that there's no way a sneeze can create pressure that would force your eyes to shoot out and dangle around like a game of swingball.
However, there are other dangers to sneezing that we wish we didn't know about. Take for instance a perfectly healthy 34-year-old man who, for reasons unknown, decided to try and block a sneeze by covering his mouth and holding his nose at the same time.
Described in a BMJ Case Report under the rather distressing title "Snap, crackle, and pop: when sneezing leads to crackling in the neck", the man showed up in a hospital emergency department after an "achoo" had gone wrong. The patient had pinched his nose and held his mouth closed when he sneezed, experiencing a "popping sensation" in his neck.
As distressing as that sounds, it got worse when he experienced painful swallowing, a pain in his throat, and a "change of voice". Upon examination, it was discovered that his neck down to his ribcage made popping and crackling sounds, a sign that he either had air bubbles inside his deep tissue and muscles or was harboring two-thirds of the Kellogg's Rice Krispies trio inside his chest cavity.
Figuring that it was more likely the former (known as Hamman’s sign, crackling can occur when the heart beats against tissue filled with air) doctors ordered a scan of his soft neck tissue and chest. This soon revealed the problem: during the act of suppressing his sneeze he had ruptured the back of his neck.
The rupture – which is more often caused by blunt neck trauma, profuse vomiting, and heavy coughing – had caused air to leak into the retropharyngeal region (see the arrow in the scan above), causing pain and loss of voice.
Fortunately, the man was able to recover from the sneeze in hospital. He was given a feeding tube and intravenous antibiotics as a precautionary measure. He was later discharged, but not before he was advised to avoid obstructing both his nostrils while sneezing.
As for the rest of you:
"Halting sneeze via blocking nostrils and mouth is a dangerous maneuver and should be avoided," the team wrote in their report. "It may lead to numerous complications such as pneumomediastinum, perforation of the tympanic membrane, and even rupture of cerebral aneurysm."