A sneeze is an involuntary reflex that forcefully expels irritants from the nasal passages. This sudden burst of air and mucus is triggered when foreign particles like dust or pollen stimulate nerve endings in the nose. Many instinctively suppress sneezes, often for social reasons. However, preventing a sneeze can redirect its considerable force internally, raising questions about its potential safety.
The Power of a Sneeze
An uninhibited sneeze involves a rapid, coordinated physiological process. Before a sneeze, a deep breath fills the lungs, and pressure builds in the respiratory system, including the sinuses, nasal cavity, and throat. The diaphragm contracts, and chest muscles tighten, culminating in an explosive expulsion of air, mucus, and irritants through the nose and mouth. This forceful release can propel droplets at speeds up to 100 miles per hour (160 km/h).
The internal pressure generated during a sneeze is substantial, measured at approximately 1 pound-force per square inch (psi) in the windpipe. This is significantly higher than pressure during strenuous exhalation. This powerful burst clears foreign particles and pathogens. When obstructed, the concentrated force redirects inward, leading to internal pressure 5 to 24 times greater than an unsuppressed sneeze.
Potential Harm from Blocking a Sneeze
Blocking a sneeze by pinching the nose and closing the mouth redirects intense pressure within the body, potentially leading to rare injuries. One risk is a ruptured eardrum, which occurs when pressurized air travels up the Eustachian tubes into the middle ear. This can cause pain, dizziness, temporary hearing loss, or a middle ear infection from redirected mucus.
Increased internal pressure can also damage blood vessels in the head and neck. Suppressing a sneeze may lead to burst capillaries in the eyes, appearing as red spots, or cause minor nosebleeds. While typically not serious, more severe consequences include a ruptured cerebral aneurysm, a life-threatening ballooning blood vessel in the brain.
Another severe, uncommon injury is a pharyngeal rupture, a tear in the back of the throat. This can lead to pain, difficulty speaking or swallowing, and the accumulation of air bubbles in the neck and chest. Individuals have required hospitalization, tube feeding, and intravenous antibiotics to heal from this trauma.
In rare situations, the immense internal force of a suppressed sneeze has been linked to diaphragm injuries or rib fractures. When high-pressure air is forced into the lungs against resistance, it can damage the diaphragm, the muscle separating the chest and abdomen, or lead to a collapsed lung. These injuries highlight the significant force involved and the hazards of containing a sneeze.
How to Sneeze Safely
Given the potential, though rare, risks of suppressing a sneeze, it is advisable to allow it to occur naturally. To minimize germ spread, use a disposable tissue. Discard the tissue immediately after sneezing to prevent the transfer of respiratory droplets.
If a tissue is not available, sneeze into the crook of your elbow instead of your hands. This contains droplets within clothing, reducing surface contamination and germ spread. After any sneeze, wash hands thoroughly with soap and water for at least 20 seconds to remove lingering germs.