It is certainly not normal for a man to have yellowish discharge on his underwear. This situation should be highly suspected of having a bacterial infection, and it is recommended to pay attention to whether there is scabbing at the urethra and whether there is discharge from the urethra. Also pay attention to whether there is a history of unclean sexual intercourse, whether there is frequent, urgent and painful urination. Discharge from the urethral opening should be taken for mycoplasma, chlamydia, and gonococcal examination. Only after the examination can we know what pathogenic infection is present, and only after the diagnosis is confirmed can we carry out effective and correct treatment. Gonococcal infections should be treated with penicillin or ceftriaxone sodium, while non-gonococcal infections may need to be treated with azithromycin.