While STD symptoms differ depending on the disease in question, pain during urination and discharge from the penis are common signs of an infection in men, notes Mayo Clinic. In some cases, STDs do not show any symptoms at all, but it's still possible to transmit them, making protection necessary.
Gonorrhea involves bacterial infection inside the genital tract but also grows in the anus, mouth, eyes and throat. When symptoms occur, they usually do so within 10 days of exposure, although it sometimes takes months for symptoms to present. Men with gonorrhea may experience anal itching and pain during urination and bowel movements. The testicles also swell and hurt, and the penis issues a bloody or thick discharge, notes Mayo Clinic.
Another bacterial STD is chlamydia, which often shows no signs. If symptoms do occur, they show up between one to three weeks after exposure. Men with chlamydia experience pain in the testicles, penis discharge, pain during urination and ongoing pain in the lower abdomen. Trichomoniasis, in contrast, is a parasitic infection that spreads when someone has sex with an already infected person. Men who catch trichomoniasis experience pain during sex and urination, irritation or itching within the penis, and penis discharge, states Mayo Clinic