Many people, including medical professionals, have the misconception that paroxysmal sneezing is allergic rhinitis. In fact, it is easy to distinguish: paroxysmal sneezing throughout the day is more likely to be allergic rhinitis. Morning bouts of sneezing are more likely to be vasomotor rhinitis. Although this is not absolutely true, it is not too wrong to make this distinction. The reasoning is simple: allergic rhinitis is due to the presence of specific IgE in the blood, and paroxysmal sneezing occurs whenever there is exposure to an allergen, regardless of the time of day. The concentration of specific IgE in the blood cannot be 100 in the morning and 0 at noon or in the afternoon, so allergic rhinitis cannot occur only in the morning with paroxysmal sneezing; it should occur at any time of the day. Why is morning paroxysmal sneezing more likely to be vasomotor rhinitis? Because the so-called vasomotor rhinitis is actually due to nasal itching and paroxysmal sneezing caused by nasal itching when contact or disconnection of adjacent mucosal surfaces of the nasal cavity occurs due to the alternating process of congestion and decongestion of the submucosal vessels. During nighttime sleep, sympathetic excitability decreases and parasympathetic excitability increases, leading to congestion of the submucosal vessels in the nasal cavity, which can cause contact between adjacent mucosal surfaces of the nasal cavity; once awakened in the morning, sympathetic excitability increases and parasympathetic excitability decreases, leading to decongestion of the submucosal vessels in the nasal cavity, and when the mucosal surfaces that were in contact during sleep due to congestion separate, nasal itching and nasal sneezing can occur. Itchy nose and chronic sneezing occur. This physiological phenomenon can also occur in environments with large temperature differences, which is often referred to as “allergy to cold air”. Therefore, do not take it for granted that paroxysmal sneezing is allergic rhinitis. There is no such thing as “cold air allergy”. In addition to the medical history, the differential diagnosis of allergic rhinitis and vasomotor rhinitis requires an allergen skin test and a blood test for serum specific IgE.