Sneezing is a reflex that we all know, which is normal but can be a sign of various illnesses. It is the expulsion of air from the lungs through the nose and mouth, most often in response to irritation of the nasal mucosa.

This is a defense reflex: it allows particles, irritants or microbes that could cause infection to be expelled from the nose.

As common as it is, little is still known about sneezing. It has been little studied and its mechanisms are not fully understood.

Sneezing most often occurs in response to irritation of the nasal mucosa, caused by the presence of dust, for example.

It can also be triggered, in some people, by exposure to sunlight or bright light: this is the photo-sternutatory reflex. This would concern about a quarter of the population.

Other situations can trigger a sneeze or the urge to sneeze, depending on the person, such as having a full stomach, eating certain foods, having an orgasm, etc.

Allergies, and therefore exposure to allergens, are known to trigger bursts of sneezing, in addition to other rhinitis or watery eyes symptoms. Allergens make the nasal mucosa hypersensitive, and therefore easily irritable.

Finally, pathologies such as epilepsy or a lesion of the postero-inferior cerebellar artery can sometimes lead to unwanted sneezing.

What happens if you sneeze? The mechanisms are not fully understood, but it is known that the nasal mucosa, when irritated, relays information to the trigeminal nerve, which activates the trigeminal nucleus in the brain. It is this center that “commands” the sneezing of the muscles of the diaphragm, among others. It is therefore a nervous reflex.

This reflex involves an inspiration phase followed by an expiration phase, during which the air is expelled at a speed of about 150 km / h. The palate and the glottis direct the air towards the nose, to ensure its “cleaning”. A single sneeze would expel 100 viruses and bacteria from the nose.

Most of the time, there are no consequences: sneezing is a normal and healthy reflex.

However, there have been reports of injuries related to the violence of the sneezing, including the rupture of a rib, the onset of a myocardial infarction or the pinching of a sciatic nerve.

It is especially when the sneezes follow one another, for example in case of allergy, that they can become annoying.

Better to wait for the sneeze to pass. If the need arises at an inappropriate time, you can try to pinch the tip of your nose while blowing through your mouth, just to try to “block” the reflex.

Finally, if the sneezing is too frequent, it is better to consult to find the cause. Antihistamine treatments can relieve allergy symptoms, for example. Bless you !