A sneeze, medically known as sternutation, is a sudden, convulsive expulsion of air from the lungs through the nose and mouth. This powerful, involuntary reflex serves as a protective mechanism designed to forcefully clear the nasal passages of irritants like dust, allergens, or microbes. The action generates substantial internal pressure. When a person attempts to suppress this reflex by blocking the natural exit points, the intense force created has no way to escape, establishing the core danger of the practice.
The Mechanics of the Sneeze Reflex
The physiological process of a sneeze begins with a deep inhalation, followed by the contraction of muscles in the chest and abdomen. These actions rapidly build up a significant volume of pressurized air within the respiratory system. The final stage is an explosive exhalation, where the air is forcefully expelled through the nasal cavity and mouth.
The magnitude of this expulsion is high, often reaching nearly 100 kilometers per hour (about 62 miles per hour). This high velocity is necessary to dislodge and clear foreign particles or mucus lining the nasal cavity. The sneeze functions to release pressure and clear the irritant, highlighting the sheer force the body is designed to release.
Consequences of Internal Pressure Diversion
When a person pinches their nose shut and closes their mouth to stop a sneeze, they seal the primary exit for this high-velocity air. This sudden blockage causes the pressure built up in the lungs and upper airways to be redirected into adjacent closed cavities within the head and chest. The pressure can increase dramatically, sometimes reaching 5 to 24 times the pressure generated during a normal, unsuppressed sneeze.
One immediate pathway for this redirected pressure is upward through the Eustachian tubes, which connect the back of the nose to the middle ear. The force can also be driven downward into the delicate structures of the throat, including the pharynx and larynx. This internal diversion attempts to find the path of least resistance, often leading it to the body’s more fragile tissues.
Documented Risks and Specific Injuries
The redirection of pressure into sensitive areas can lead to documented medical complications. One common consequence is damage to the ear, where pressurized air traveling up the Eustachian tubes can rupture the tympanic membrane, or eardrum. In severe cases, this pressure can damage inner ear structures, potentially causing temporary or permanent hearing loss.
Another serious risk involves the throat, where the force can cause laryngeal or pharyngeal perforation, tearing the throat tissue. A documented case reported a man who developed a small tear in his windpipe after stifling a sneeze, causing air to accumulate in the chest cavity (pneumomediastinum). Though rare, the pressure has also been linked to fractured ribs and, in individuals with pre-existing conditions, the rupture of a brain aneurysm.
Additionally, the temporary spike in internal pressure can cause small blood vessels in the eyes or nose to burst, resulting in a minor subconjunctival hemorrhage. If sneezing in public is unavoidable, the safest method is to release the air into the crook of the elbow or a tissue, rather than attempting to suppress the reflex itself.