Sneezing is a reflexive action that is caused by an irritation in the nose. It is usually accompanied by a loud noise, a closing of the eyes, and an involuntary exhalation of air. It can be caused by allergies, colds, or other irritants. Sneezing typically starts with a tickling sensation in the nose, followed by a deep inhalation and a forceful exhalation. It can be accompanied by a runny nose, watery eyes, or a headache. Sneezing can also be symptomatic of more serious conditions such as asthma or sinus infections.