The precursors of sexually transmitted diseases in men may include abnormal bulges, abnormal discharge, abnormal urination sensation, enlarged lymph nodes and so on. 1. Abnormal bumps: abnormal bumps, such as blisters, bumps, small nodules, can be found on the genitals or surrounding skin, sometimes without obvious symptoms. Sometimes there are no obvious symptoms. For example, small hard nodules and ulcers may appear in syphilis infection, and clustered blisters may appear in genital herpes infection. 2. Abnormal secretion: abnormal secretion can be seen around the urethra or anus. Such as gonorrhea may appear sticky or purulent secretion, genital herpes may appear rectal secretion and so on. 3. Abnormal urinary sensation: such as gonorrhea, condyloma acuminatum and other sexually transmitted diseases, there will be frequent urination, urinary urgency, urinary pain, burning, itching and redness of the urethra and so on. 4. Enlarged lymph nodes: If infected with soft chancre or lymphogranuloma venereum, the inguinal lymph nodes can be seen to be enlarged and painful. Sexually transmitted diseases need timely treatment, if there is any discomfort, please consult a doctor in time, so as not to delay the condition.