Correct use of nasal aspirator will not cause harm, such as improper operation may cause damage to nasal mucosa, infection, nasal environment damage, etc. 1. Infection: when applying nasal wash, if the rinsing solution is contaminated, or if the force is too strong and the water flow is too large, it may damage the mucosa of the nasal cavity and cause retrograde infection, which may increase the risk of pathogenic bacteria and secretions entering the middle ear cavity through the Eustachian tube, and even induce otitis media; 2. Destroying the nasal environment: nasal washers are a means of adjunctive treatment and cannot be used very frequently. If used frequently, it may damage the physiological environment of the nasal cavity, affecting the normal filtration of the nasal cavity, anti-bacterial function, which may lead to the emergence of nasal dryness, itching and other symptoms. It should be noted that the nasal washer should be used in accordance with the instructions or under the guidance of a doctor, otherwise there may be infections, aggravation of the symptoms of rhinitis or the emergence of nasal dryness and other hazards.