Allergic rhinitis is a metaplastic disease of the nasal mucosa characterized by recurrent sneezing, watery nasal discharge, nasal congestion and nasal itching. Perennial allergic rhinitis is mostly caused by indoor allergens, such as dust mites, mold spores, animal hair, dander, fungi, etc., while seasonal allergic rhinitis is mostly caused by outdoor allergens, such as pollen. Diagnosis of allergic rhinitis Allergic rhinitis should be highly suspected when 2 or more of these symptoms, such as runny nose, sneezing, nasal congestion and nasal itching, occur and last for more than 1 hour. Skin prick test or serum IgE level measurement can be performed to assist in the diagnosis. Allergic rhinitis treatment 1. Avoid contact with allergens There are many ways to avoid contact with indoor allergens, such as not laying carpets indoors, laying allergen impenetrable cloth covers on mattresses and pillows, installing and using high efficiency air filtration systems indoors, and keeping indoor relative humidity <50% are all effective methods. Studies have shown that the efficiency of using 60℃ and 30℃ hot water to remove indoor dust mites and other allergens is 26.8% and 0.6% respectively. For patients allergic to animal fur and dander, they should avoid keeping pets or keeping them outdoors as much as possible. The first generation of antihistamines (such as paracetamol, diphenhydramine, promethazine, etc.) are not highly selective for Hl receptors and have significant sedative and anticholinergic effects, so they are not recommended for the treatment of allergic rhinitis. The 2nd generation antihistamines are commonly used clinically because they have no obvious sedative effect, and include loratadine, desloratadine, cetirizine, levocetirizine, imipramine, epastine, fexofenadine, lupatadine, etc. (2) Intranasal steroids (hormones) Fluticasone propionate nasal spray, beclomethasone nasal spray, etc. (3) Decongestant drugs Decongestant drugs can effectively relieve the symptoms of nasal congestion, but they cannot better relieve the symptoms of sneezing, nasal itching and eye discomfort caused by allergic rhinitis. Drug rhinitis is the most common adverse reaction after local use of drugs. Commonly used are 1% ephedrine solution, nasal drops, etc. (4) Leukotriene receptor antagonists The effectiveness is basically equivalent to that of oral antihistamines. The common leukotriene receptor antagonists on the market are pramlintide and montelukast. Immunotherapy Immunotherapy is a method of treating the root cause of allergic diseases by desensitizing and establishing an allergen-free state. Immunotherapy involves injecting allergen extracts subcutaneously into patients with allergic rhinitis and gradually increasing the dose until a maintenance dose is reached and the treatment is maintained (≥3 years). Therefore, this immunotherapy is also known as subcutaneous immunotherapy. It is not widely used in clinical practice because it can also cause allergic reactions and carries certain risks.