STIs in Men: Symptoms, Transmission, and What to Expect from Testing
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Common STIs That Affect Men
Sexually transmitted infections (STIs) are among the most common health concerns in adult men, yet many go undiagnosed due to absent or mild symptoms. For a broader foundation, see our introduction to men's sexual health core concepts.
| Most common bacterial STI in men | Chlamydia (Centers for Disease Control and Prevention (CDC)) |
| Percentage of chlamydia cases that are asymptomatic in men | ~50% (CDC, STI Surveillance Report) |
| HPV vaccine recommended age range | Up to age 26 (routine); 27–45 with clinical guidance (CDC Advisory Committee on Immunization Practices) |
| HIV treatment outcome | Undetectable viral load achievable with ART (National Institutes of Health (NIH)) |
| Testing methods used | Urine, blood, and swab samples |
| Syphilis stages | Primary, secondary, latent, and tertiary (World Health Organization (WHO)) |
The STIs most frequently diagnosed in men include:
- Chlamydia: Often called a "silent" infection — most men experience no symptoms. When present, signs include a burning sensation during urination or discharge from the penis.
- Gonorrhoea: May cause yellow or white penile discharge, painful urination, or swollen testicles. Can also infect the throat or rectum with few obvious signs.
- Syphilis: Progresses in stages. A painless sore (chancre) typically appears first, followed by a rash, flu-like symptoms, and — if untreated — serious organ damage years later.
- Human Papillomavirus (HPV): The most common STI overall. Many strains cause no symptoms; others produce genital warts. Certain high-risk strains are linked to cancers of the throat, anus, and penis.
- Herpes (HSV-1 and HSV-2): Causes recurring sores or blisters around the genitals or mouth. Many people are unaware they carry the virus because outbreaks can be mild or absent.
- HIV: Attacks the immune system. Early infection may resemble flu; over time, untreated HIV can progress to AIDS. Modern treatment allows people with HIV to live long, healthy lives.
STI (Sexually Transmitted Infection)
An infection passed from person to person primarily through sexual contact. The term "STI" is now preferred over "STD" (sexually transmitted disease) in clinical settings, as it more accurately reflects that many infections cause no disease symptoms.
Asymptomatic
Having an infection with no noticeable signs or symptoms. Many STIs, including chlamydia and HIV in early stages, can be asymptomatic — making regular testing essential for early detection.
Chancre
A painless, firm sore that typically appears at the site of syphilis infection. It is the hallmark sign of primary-stage syphilis and may go unnoticed because it does not cause pain.
Window Period
The time between exposure to an infection and when a test can reliably detect it. Testing too early — within the window period — can produce a false-negative result.
Antiretroviral Therapy (ART)
A combination of medications used to suppress HIV to undetectable levels in the blood. ART does not cure HIV but allows people living with the virus to maintain a healthy immune system and dramatically reduces transmission risk.
HPV (Human Papillomavirus)
A group of more than 200 related viruses, several of which are sexually transmitted. Some strains cause genital warts; others are associated with certain cancers. Vaccination is available and recommended.
How STIs Are Transmitted
Understanding transmission routes helps men make informed decisions about protection. Most STIs spread through:
- Unprotected vaginal, anal, or oral sex — the primary route for chlamydia, gonorrhoea, syphilis, herpes, HPV, and HIV.
- Skin-to-skin genital contact — relevant for herpes and HPV, which can transmit even without penetration.
- Sharing needles or syringes — a significant transmission route for HIV and hepatitis B and C.
- Blood-to-blood contact — applies to HIV and some hepatitis strains.
Consistent and correct use of condoms significantly reduces — though does not eliminate — the risk of most STIs. Vaccines are available for HPV and hepatitis B and are recommended as part of routine preventive care. Speak with a healthcare professional about what preventive options may be appropriate for you.
1 in 5
Americans with an STI at any given time
According to CDC estimates, approximately 1 in 5 people in the United States has a sexually transmitted infection at any point in time.
~2.5M
New chlamydia, gonorrhoea, and syphilis cases reported annually in the US
The CDC's annual STI surveillance data consistently documents millions of new bacterial STI diagnoses each year in the United States.
Over 90%
Reduction in genital wart risk from HPV vaccination
Clinical trials and post-licensure studies show HPV vaccines are highly effective at preventing infection from the strains covered by the vaccine.
What to Expect from STI Testing
Testing is the only reliable way to know whether you have an STI. Many infections produce no noticeable symptoms, making routine screening essential rather than optional. Our guide on sexual health screening for men covers which tests are typically recommended and how often.
A standard sexual health screen may involve one or more of the following:
- Urine sample: Used to test for chlamydia and gonorrhoea.
- Blood tests: Required to detect HIV, syphilis, and hepatitis B and C.
- Swabs: Taken from the urethra, throat, or rectum depending on the type of sexual contact reported. Also used to identify herpes sores during an active outbreak.
- Physical examination: A clinician may examine the genitals for warts, sores, or unusual discharge.
Testing is generally quick, straightforward, and confidential. Many clinics and online services offer self-collection kits for greater privacy. If you're unsure how to approach the conversation with a doctor, our guide to talking to a doctor about sexual health explains what a typical consultation involves.
Window Periods Can Affect Test Accuracy
Early diagnosis matters. Most STIs are treatable — and many are curable — when caught promptly. Untreated infections can lead to complications including infertility, chronic pain, and increased HIV risk. If you have concerns, see a healthcare provider rather than waiting for symptoms to appear.
This article is for general informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for personal health concerns, symptoms, or before making decisions about testing or treatment.
The content on this site is for informational purposes only and is not a substitute for professional advice. Always consult a qualified professional for guidance specific to your situation.