What causes redness at the male urethral opening?

The most common cause of redness at the male urethral meatus is infection, which may be caused by various pathogens—including bacteria, viruses, mycoplasma, and chlamydia—with bacterial infection being the most frequent. Redness at the urethral meatus is often accompanied by discharge; thus, a sample of the discharge can be collected for bacterial culture and antimicrobial susceptibility testing. If urinalysis reveals white blood cell casts or bacterial clusters, this strongly suggests a bacterial infection, and targeted antimicrobial therapy can then be guided by the susceptibility results. Commonly used antibiotics include levofloxacin, cephalosporins (e.g., cefaclor, cefixime), and penicillin derivatives such as amoxicillin-clavulanate or piperacillin-sulbactam.

In cases of mycoplasma or chlamydia infection, urethral meatal redness may also occur; treatment typically involves macrolides such as clarithromycin, azithromycin, or roxithromycin. For viral infections causing urethral meatal redness, no specific antiviral therapy is available; instead, topical antiseptics—such as povidone-iodine—may be used more frequently. Additionally, certain sexually transmitted infections (STIs) in men can present with urethral meatal redness; the most common is gonorrhea, which generally requires high-dose penicillin or cephalosporin therapy.