Sneezing is primarily caused by irritation or stimulation of the mucous membranes inside the nose. This irritation activates the trigeminal nerve, which sends signals to the brain to initiate the sneeze reflex. The body then forcefully expels air from the lungs through the nose and mouth to clear out the irritants. Common triggers include allergens like pollen, dust, mold, and pet dander; environmental irritants such as smoke, pollution, cold air, and strong odors; viral infections like colds and flu; sudden exposure to bright light (photic sneeze reflex); and even a full stomach (known as the snatiation reflex).
The sneeze reflex involves multiple muscles working together, including those in the abdomen, chest, throat, vocal cords, and eyes (which involuntarily close during a sneeze). Sneezing is an important protective mechanism to expel mucus containing foreign particles, pathogens, or irritants from the nasal passages and help keep the respiratory system clear.
