The most common STDs in the United States are chlamydia, gonorrhea, syphilis, HPV, herpes, trichomoniasis, and HIV. In 2024 alone, more than 2.2 million cases of just chlamydia, gonorrhea, and syphilis were reported to the CDC, and millions more infections from HPV, herpes, and trichomoniasis go unreported because they aren’t tracked the same way. Many of these infections cause no symptoms at all, which is why they spread so easily and why routine testing matters.
Chlamydia
Chlamydia is the single most reported STD in the country, with nearly 1.52 million cases reported in 2024. It’s caused by bacteria and spreads through vaginal, anal, or oral sex. More than half of people with chlamydia have no symptoms whatsoever, which means it often passes between partners undetected for weeks or months.
When symptoms do appear, they typically show up one to three weeks after exposure. Women may notice unusual vaginal discharge or burning during urination. Men may experience discharge from the penis or mild pain in the testicles. Left untreated, chlamydia can lead to pelvic inflammatory disease in women, which can cause chronic pain and fertility problems. The good news: a simple course of antibiotics clears it up. The CDC recommends that all sexually active women under 25 get tested for chlamydia every year, along with women 25 and older who have new or multiple partners.
Gonorrhea
Gonorrhea was the second most reported STD in 2024, with about 543,400 cases. Like chlamydia, it’s bacterial and treatable with antibiotics, and it can infect the genitals, rectum, and throat. Gonorrhea tends to produce symptoms more often than chlamydia, though fewer than half of infections are still completely silent.
Symptoms, when present, usually appear within two to eight days. They can include painful urination, unusual discharge, and in women, bleeding between periods. One growing concern with gonorrhea is antibiotic resistance. Some strains have become harder to treat over the years, which is why doctors now use specific antibiotic combinations and may follow up to confirm the infection is gone. Testing recommendations mirror those for chlamydia: annual screening for sexually active women under 25 and for men who have sex with men.
Syphilis
Syphilis has been surging over the past decade, though 2024 brought some encouraging news. Cases of primary and secondary syphilis, the most infectious stages, dropped 22% compared to 2023. Still, over 190,000 total syphilis cases were reported in 2024, and congenital syphilis (passed from mother to baby during pregnancy) remains 700% higher than it was ten years ago, with nearly 4,000 cases in 2024.
Syphilis progresses through distinct stages if untreated. The first sign is typically a painless sore at the site of infection, appearing an average of three weeks after exposure but sometimes taking up to 90 days. Because the sore doesn’t hurt, many people never notice it. The second stage brings a body rash, often on the palms and soles of the feet, along with flu-like symptoms. After that, the infection can go dormant for years before causing serious damage to the heart, brain, and other organs. Antibiotics are highly effective at every stage, but damage from late-stage syphilis can’t be reversed.
HPV (Human Papillomavirus)
HPV is arguably the most common sexually transmitted infection of all, though it doesn’t appear in annual case counts because it isn’t a reportable disease. More than 42 million Americans currently have strains of HPV known to cause disease, and the CDC estimates that nearly everyone who isn’t vaccinated will get HPV at some point in their lives.
Most HPV infections clear on their own within one to two years without causing any problems. Certain strains cause genital warts, while other “high-risk” strains can lead to cervical, throat, anal, and penile cancers over time. The HPV vaccine is the most effective protection and is recommended for everyone through age 26, with the best results when given between ages 9 and 12. Routine cervical cancer screening (Pap tests and HPV tests) catches precancerous changes early in women, which is why those screenings remain important even for vaccinated individuals.
Genital Herpes (HSV-2)
About 12% of Americans aged 14 to 49 have genital herpes caused by HSV-2. That translates to roughly one in eight people in that age group. HSV-1, traditionally associated with cold sores on the mouth, can also cause genital herpes through oral sex, making the true number of genital herpes cases even higher.
Herpes symptoms, when they occur, typically appear 2 to 12 days after exposure as painful blisters or sores around the genitals or rectum. Many people have symptoms so mild they mistake them for ingrown hairs or skin irritation. After the first outbreak, the virus stays in the body permanently and can reactivate periodically, though outbreaks tend to become less frequent over time. There’s no cure, but daily antiviral medication reduces outbreaks and significantly lowers the chance of passing the virus to a partner. Blood tests can detect herpes antibodies, but it takes up to four months after exposure for the test to reliably catch an infection.
Trichomoniasis
Trichomoniasis is caused by a parasite rather than a bacterium or virus, and it’s far more common than most people realize. The CDC estimates over two million infections occur in the U.S. each year. It’s more common in women than men, and about 70% of infected people have no symptoms at all.
Women who do develop symptoms often notice itching, burning, or redness around the genitals, discomfort when urinating, and a thin or frothy vaginal discharge that may have a fishy smell. Men may experience irritation inside the penis, burning after urination or ejaculation, and mild discharge. Trichomoniasis is easily cured with a single dose of oral antibiotic medication, and both partners need to be treated at the same time to prevent reinfection.
HIV
HIV is less common than the infections above, with 39,201 new diagnoses in 2023, but it remains one of the most serious STDs because it attacks the immune system and, without treatment, progresses to AIDS. Modern antiretroviral therapy has transformed HIV from a fatal diagnosis into a manageable chronic condition. People who start treatment early and take it consistently can reach an undetectable viral load, meaning they effectively cannot transmit the virus to sexual partners.
Early HIV infection sometimes produces flu-like symptoms (fever, body aches, fatigue) within one to two weeks, but many people experience nothing noticeable. After that initial phase, the virus can remain silent for months or years while quietly damaging the immune system. The CDC recommends that everyone between ages 13 and 64 get tested at least once, with more frequent testing (every 3 to 6 months) for men who have sex with men and anyone who shares injection drug equipment. Preventive medication called PrEP reduces the risk of getting HIV by about 99% when taken as prescribed.
When to Get Tested
Because so many STDs produce no symptoms, testing is the only reliable way to know your status. How soon a test can detect an infection depends on the STD. Chlamydia and gonorrhea can be picked up on a test as early as one week after exposure, with two weeks catching nearly all infections. Syphilis and HIV take longer: most infections show up on a blood test within a month, but a three-month window catches almost all cases. Herpes antibody tests need up to four months to be fully reliable.
If you’re sexually active with new or multiple partners, annual screening for chlamydia, gonorrhea, and syphilis is a reasonable baseline. A one-time HIV test is recommended for all adults, with annual or more frequent testing for higher-risk groups. Your testing schedule may look different depending on your age, sex, number of partners, and whether you use barrier protection consistently. The practical takeaway is simple: if you’ve had unprotected sex or a new partner and aren’t sure of their status, getting tested is quick, widely available, and for most of these infections, leads to straightforward treatment.