Instant gelling agent for treating allergic rhinitis

The invention belongs to the field of western medicinal preparation, and relates to a preparation with suitable phase variation, detention time prolonging effects and topically administered in nasal cavity, and its preparation method. The method comprises dispersing momestasone furoate or budesonide in hydrophilic gel substrate prepared from acetyl-removed gellan gum and sodium alginate in micro powder form. the gel preparation is prepared and stored in solution from, and administered in solution spraying form; generates phase variation due to the change of environmental ionic strength, pH, or temperature after contacting with tunica mucosa of nasal cavity, and forms gel. The invention has the advantages of simple preparation and accurate administered dose; can prolong the contact time of medicine and schneiderian membrane; and improves therapeutic effect of the medicine to anaphylactic rhinitis.