Inflammation of the urethra, painful urination and fever are caused by urinary tract infections, which include upper urinary tract infections and lower urinary tract infections. 1. Upper urinary tract infection: acute pyelonephritis is common. Clinical manifestations include chills, high fever, low back pain on the affected side or both sides, and bladder irritation. Some patients may have systemic symptoms such as headache, vomiting and urinary tract irritation. 2. Lower urinary tract infection: including cystitis and urethritis. Cystitis: manifested by frequent urination, urgency, urinary pain, burning sensation in the urethra. Common terminal hematuria, systemic symptoms are not obvious. Urethritis: manifested as urethral mucosa redness, swelling, itching and stinging. The urethra discharges a large amount of yellowish-white purulent discharge, followed by frequent urination, urinary urgency, urinary pain and other symptoms. If you find symptoms such as inflammation of the urethra, painful urination and fever, you should go to the hospital in time to determine the site of infection, and under the guidance of the doctor for treatment.