The urethral opening is red and painful, then the possible causes: first, mechanical physical stimulation caused by, for example, long-term friction urethral opening, resulting in local reactive redness, accompanied by local erosion and pain. Mostly seen in the lack of attention to personal hygiene, the local presence of foreskin scale, the formation of chronic stimulation, or long-term masturbation, local stimulation of the urethra and lead to mechanical damage to the pain. Need to do a good job of personal hygiene cleaning, avoid some bad vices, do not need to use any drugs. Second, when local contact infection caused by bacteria, fungi, trichomonas, etc. occurs, redness of the urethra can occur. At the same time may be accompanied by glans foreskin redness, swelling, erosion and other reactions, need to carry out the corresponding pathogenic examination, clear pathogen after giving antifungal, anti-infective and other drugs symptomatic treatment.