Sneezes

Sneezes are a rapid, forceful expulsion of air from the nose and mouth, produced by a reflex that helps clear irritants from the nasal passages. A sneeze is usually brief and can occur as a single event or in a series.

Physiology and mechanism: Irritants such as dust, pollen, smoke, or viral particles stimulate receptors in the nasal mucosa. Signals travel via the trigeminal nerve to a brainstem reflex center that coordinates a deep inhalation, a closing of the mouth and glottis, and the contraction of chest and abdominal muscles, culminating in a powerful outward blast of air.

Triggers and variation: Common triggers include environmental irritants, allergens, infections (such as the common cold or flu), and changes in temperature or humidity. Some people experience the photic sneeze reflex, a hereditary tendency to sneeze in bright light. Sneezing can occur once or in rapid succession and is often influenced by individual sensitivity and context.

Health, hygiene, and context: Sneezing serves as a protective reflex to remove irritants. It also spreads respiratory droplets, so etiquette and hygiene are advised, such as covering the nose and mouth and using a tissue or elbow to reduce transmission. Most sneezing is harmless and short-lived, but persistent sneezing, sneezing with fever, unusual nasal discharge, or blood may warrant medical evaluation to assess allergies, infections, or other conditions.