If a fly has entered the nose you should press the side of the nostril that has not entered the fly and blow your nose hard to blow the fly out like snot. However, if this does not solve the problem, you can use nasal sprays, such as anti-allergy sprays like Nenasol and Renolcort, or you can spray your nose with physiological seawater. It is best to kill the fly and then go to the hospital to remove the fly from your nose with gun-like tweezers, or remove the fly after finding it under a nasal endoscope. If the flies keep moving, it is important to prevent them from going further down the nasopharynx, if they go down the nasopharynx to the mouth and spit them out, but it is important to prevent them from entering the airway and causing suffocation.