Stinging pain in the urethra when urinating refers to stabbing pain in urination, which may be caused by diseases such as urethritis, urethral stones, pyelonephritis and so on. 1. Urethritis: mainly bacteria invade the urethra causing inflammation of the urethra, and the urine stimulates the inflamed urethra during urination and causes pain. 2. Urethral calculi: stones in the urethra are mostly from the kidneys and bladder, when the stones are discharged into the urethra, the stones rub the surface of the urethra and urinary pain occurs, and if the stones are large, it will also cause urethral blockage, which will be manifested as difficulty in urination. 3. Pyelonephritis: It is mostly caused by retrograde infection of bacteria through the urethra, and pain will occur when urinating due to inflammation of the renal pelvis. The main symptoms are frequent urination, urgency, pain in urination, which may be accompanied by back pain. There are many other causes of painful urination, which should be treated promptly by a doctor.