The Cause of Sneezing

It seems that everyone sneezes at times​—old and young, adults and babies. Even animals are known to sneeze. In most cases the cause is a foreign object (such as dust or pollen) that irritates the nasal passages.

Sensitive nerve endings react to the presence of an irritating substance by sending a message to the brain. It then instructs the nose to provide a watery fluid to assist in the removal of the unwanted object. The brain also passes messages to the lungs so that a lungful of air is inhaled, then to the vocal cords to seal off the air passage and prevent the air from escaping. The muscles of the chest wall and abdomen are told to tighten, thus compressing the air in the lungs. Finally, the vocal cords are ordered to relax, and the compressed air is rapidly expelled, usually dislodging the unwanted irritant along with the watery fluid. All of this takes place without conscious effort and much more quickly than it takes to read about it.

In most cases, constant sneezing is a symptom of a common allergy called hay fever. Plant pollen provides the irritation, and although the name hay fever may suggest that hay or newly mowed grass is the culprit, this may not always be the case. Sufferers may be allergic to a number of different pollens, or perhaps just one. So it is easy to understand why hay-​fever sufferers dread seasons when strong, dry winds blow for days. Once the nasal passages are irritated and continuous sneezing begins, the slightest dust particle that normally would not cause irritation seems to start the victim on another bout of sneezing.