The odor and fishy smell below can be seen in women as well as men. In women, bacterial vaginitis and trichomoniasis are the most common causes. Keep the vulva clean, bathe regularly and change underwear. If men have bad odor or fishy smell underneath, it may be urethritis or glansitis, which requires medication or surgery, and keep hygiene and cleanliness in general. A woman 1, bacterial vaginitis: systemic medication with anti-anaerobic drugs, the first choice is metronidazole, other commonly used drugs and tinidazole, clindamycin, etc.. Local medications are mainly metronidazole preparations or clindamycin ointment. For recurrence, lactobacillus vaginalis preparations can be used to restore the vaginal micro-ecological balance. 2. Trichomonas vaginitis: For trichomonas vaginitis it is not easy to be cured by local medication alone, so systemic medication is needed at the same time, commonly used drugs are metronidazole or tinidazole. Topical medication can relieve the symptoms faster, but it is not easy to eliminate trichomonas completely and it is easy to relapse after stopping medication. Trichomoniasis is mainly transmitted by sexual intercourse. Sexual partners should be treated at the same time and told to avoid unprotected sex until cured. Second, male men with odor and fishy smell underneath are considered to have urethritis or glansitis, especially glansitis caused by anaerobic bacteria, which is prone to odor and fishy smell. Patients can be treated with sensitive antibiotics, and patients with circumcision after the inflammation is controlled. Normally, you should wash your lower body daily and change your underwear regularly to maintain hygiene.