Sneezing is a protective mechanism designed to forcefully expel foreign particles and irritants from the nasal cavity. This reflex begins when the sensitive lining of the nose detects a trigger, signaling the brainstem to initiate the expulsion of air. While the urge to stifle a sneeze in public may be strong, experts advise against suppressing this natural, high-pressure event. Blocking the exit channels redirects the significant internal force, which can lead to a variety of internal complications.
The Mechanics of Explosive Pressure
A sneeze involves a deep inhalation followed by the forceful contraction of the chest and abdominal muscles against a temporarily closed epiglottis. This action compresses air within the respiratory system, generating a sudden, immense burst of pressure. In a normal, unobstructed sneeze, the air pressure generated in the trachea can reach approximately 7,000 Pascals (Pa).
This powerful force clears the nasal passages, expelling a large volume of air. While older estimates suggested speeds over 200 miles per hour, modern analysis indicates the expelled air reaches a maximum velocity closer to 10 miles per hour. The danger of suppression lies not in the speed, but in the resulting internal pressure.
When a person attempts to hold a sneeze by pinching the nose or clamping the mouth shut, the escape route for compressed air is sealed off. This causes the pressure to build dramatically inside the upper respiratory tract. Studies show that suppressing a sneeze can increase the internal pressure by a factor of 5 to 24 times compared to an open sneeze. This redirected, hyper-pressurized air then seeks the path of least resistance through the body’s interconnected cavities.
Anatomical Risks of Suppressing a Sneeze
The sudden, excessive pressure from a suppressed sneeze can cause damage in the head and chest. One common consequence is barotrauma, or pressure-related injury, to the ears. The force travels up the Eustachian tubes, potentially causing a rupture of the eardrum. This event can cause severe pain, temporary hearing loss, and may require surgical repair.
The redirection of air pressure can also force mucus and bacteria from the nasal passages into the middle ear. This can lead to an acute middle ear infection, which requires medical treatment. The intense, momentary spike in pressure can also affect the vascular system.
In the head, the sudden pressure surge can cause small blood vessels, or capillaries, to burst. This is often seen in the eyes, resulting in a subconjunctival hemorrhage—a red patch on the white of the eye that is visually alarming. More serious, albeit rare, cases involve the risk of rupturing existing, weakened blood vessels in the brain or neck. This risk is especially pertinent in individuals with pre-existing conditions like aneurysms.
The forceful internal redirection of air can cause structural damage to the throat and chest cavity. Documented cases include a tear, known as a pharyngeal perforation, in the tissue of the throat. This injury can lead to significant pain, difficulty swallowing, and requires immediate medical attention. In extremely rare instances, the pressure has been linked to pneumomediastinum, where air is forced into the chest cavity between the lungs, and even rib fractures.
Safe and Hygienic Alternatives
Since suppressing a sneeze carries health risks, managing the reflex safely and hygienically is necessary. When a sneeze is imminent, the most effective technique is to allow the expulsion of air while minimizing the spread of respiratory droplets. The preferred method involves sneezing into the crook of the elbow or the upper sleeve, as this contains the droplets more effectively than using a hand.
The elbow acts as a barrier, preventing the direct transmission of mucus and saliva onto surfaces that are frequently touched, such as doorknobs or phones. If a tissue is available, it should be used to cover the mouth and nose completely, and then disposed of immediately after the sneeze.
Following any sneeze, it is important to practice immediate hand hygiene. Washing hands thoroughly with soap and water is the best way to eliminate germs and prevent their spread to other people or surfaces. This simple action allows the body to complete its protective reflex without compromising personal health or the health of others.