The Centers for Disease Control and Prevention estimates that nearly 20 million new cases of sexually transmitted disease, or STDs, are diagnosed yearly 2. But it's a topic many people are embarrassed to talk about. STDs are caused by infectious organisms that are passed from one person to another through sexual contact and exchange of body fluids. STD symptoms in men vary but may include penile discharge, painful urination or skin lesions. Early identification of STD symptoms is important to prevent long-term complications and transmitting STDs to others.

Painful Urination

Painful urination is a common STD symptom in men, particularly with gonorrhea and chlamydia. When organisms enter the penis, they may infect and irritate the urethra, which is the small tube that allows urine to flow from the body. A urethral infection is called urethritis. Untreated urethritis can lead to scarring and narrowing of the urethra, which can increase the risk of bladder and kidney infections.

Penile Discharge

Urethritis from STDs such as gonorrhea, chlamydia or trichomonas may cause a puslike or milky drainage from the penis. When this discharge is swabbed and tested in the lab, chlamydia and gonorrhea are the most common culprits identified. Because these two STDs often occur together, doctors usually give antibiotics to treat both infections.

Skin Lesions

Some STDs cause rashes or other types of skin lesions. Genital herpes can cause clusters of painful blisters along the penis, buttocks or anus. These sores may persist for weeks and recur periodically. Certain strains of human papillomavirus cause warts on the penis or in the genital or anal area. An STD called chancroid causes painful ulcers on the genitals. Syphilis first presents as a small, firm, painless sore on the genitals that heals within 2 months. Untreated syphilis progresses to the next phase of the disease with a red rash that often appears on the palms of the hands and soles of the feet, but it may also affect other areas of the body.

Testicular Pain

Some STDs may travel from the urethra and infect the organs of a man's reproductive system, like the epididymis and the testes. The epididymis sits on top of the testis. It stores and transports sperm. The testes are where sperm and testosterone are produced. When these organs are infected by an STD, it can cause pain, fluid collection, or swelling in one or both testicles. Fever, nausea and vomiting may also occur.

Other Concerning Symptoms

Enlarged lymph nodes in the groin may signal an STD, such as syphilis or chancroid. They feel like firm lumps beneath the skin and may be tender. Swollen lymph nodes in other areas of the body along with flulike symptoms -- low fever, body aches, sore throat and lack of energy -- may indicate early HIV infection. Untreated syphilis can eventually damage the kidneys, liver, nervous system and heart. Symptoms may include difficulty walking, swelling in the body or shortness of breath.

When to See a Doctor

Seek medical attention if you're concerned you might have an STD. Early diagnosis and treatment reduces the risk for complications -- and potential spread of the disease to others.