A painful red and swollen bump on the nostril can be caused clinically by a variety of diseases, commonly boils and nasal polyps inside the nasal cavity, or it may be caused by folliculitis. In cases where the pain is tolerable, it can be observed for a few days and may gradually heal on its own. If the pain continues to worsen or does not heal for a long time, you can promptly seek medical examination and professional treatment.1. Boils: If you often pick or dig your nose with your hands, it is easy to cause damage to the mucous membrane inside the nasal cavity, which provides favorable conditions for bacterial infection. Boils can occur when bacteria invade the hair follicles or around the hair follicles in the nostrils and produce purulent inflammation. The clinical manifestations are red, swollen and hard pockets, which may be accompanied by pain and, in severe cases, pus. If the boil in the nostril appears to fluctuate, it should be promptly cut open and drained, followed by local application of mupirocin ointment, fusidic acid cream, etc. for anti-infection treatment. 2. Nasal polyp: It is a hyperplastic tissue that occurs in the nostril, often secondary to the inflammatory reaction in the nostril, and can develop unilaterally or bilaterally, and is often clinically manifested as a light red mass, usually not accompanied by pain, but when the polyp surface breaks down, secondary infection can However, when the polyp surface breaks down and secondary infection occurs, there is pain, redness and swelling, often accompanied by increased nasal secretions and olfactory disturbance. Patients need to undergo rhinoscopic examination to clarify the diagnosis, and in the case of meeting the indications for surgery, it can be surgically removed; 3. Folliculitis: When the patient’s immunity is low, germs invade the hair follicles in the nostrils, resulting in folliculitis, which manifests as a red and swollen mass, usually smaller than a boil, and slightly less painful. It can be treated by topical application of antibiotic ointment, such as erythromycin ointment and mupirocin ointment.