The three most common STDs in the United States, based on reported cases, are chlamydia, gonorrhea, and syphilis. In 2024, the CDC recorded roughly 1.5 million chlamydia cases, 543,409 gonorrhea cases, and 190,242 syphilis cases. All three are bacterial infections, meaning they’re curable with antibiotics, but each one can cause serious damage if left untreated.
It’s worth noting that if you count total infections rather than just reported cases, HPV and trichomoniasis are actually more widespread. Together with chlamydia and genital herpes, they account for 98% of all prevalent STIs. But because HPV and trichomoniasis often go undiagnosed and aren’t nationally reportable in the same way, chlamydia, gonorrhea, and syphilis dominate the official surveillance data and are the infections most people encounter in clinical screening.
Chlamydia: The Most Common by Far
Chlamydia holds the top spot by a wide margin, with roughly three times more reported cases than gonorrhea. The infection is caused by bacteria that spread through vaginal, anal, or oral sex. Its defining feature is silence: most people with chlamydia have no symptoms at all, which is why it spreads so easily and why routine screening matters so much.
When symptoms do appear, they typically include unusual discharge, burning during urination, or pain during sex. In women, the infection can quietly travel from the cervix into the uterus and fallopian tubes, causing pelvic inflammatory disease (PID). About 1 in 8 women with a history of PID have difficulty getting pregnant. The longer chlamydia goes untreated, the more likely these complications become.
The good news is that chlamydia is easy to treat, usually with a week-long course of oral antibiotics. Cases have actually been declining, down 8% from 2023 to 2024. Screening is recommended annually for all sexually active women under 25, and for older women with risk factors like new or multiple partners.
Gonorrhea: A Growing Resistance Problem
Gonorrhea is the second most commonly reported bacterial STD, with over half a million cases in 2024. Like chlamydia, it spreads through sexual contact and can infect the genitals, rectum, and throat. Cases dropped 10% from 2023 to 2024, continuing a three-year decline.
The symptom picture differs between men and women. Men with urethral gonorrhea typically develop noticeable symptoms, including discharge and painful urination, that push them to seek treatment relatively quickly. Women, on the other hand, are commonly asymptomatic or don’t recognize symptoms until complications like PID have already developed. This asymmetry means women often carry the infection longer and face greater risk of long-term harm.
What makes gonorrhea particularly concerning is antibiotic resistance. The bacteria have developed resistance to nearly every drug class used against them over the decades. Between 2022 and 2024, resistance to the primary antibiotics used to treat gonorrhea rose sharply. Resistance to one key injectable antibiotic jumped from 0.8% to 5%, and resistance to the main oral alternative climbed from 1.7% to 11%. An older class of antibiotics is now essentially useless, with 95% resistance rates. This trend means treatment options are narrowing, and a case of gonorrhea that doesn’t respond to first-line treatment is no longer a hypothetical scenario.
Syphilis: The Fastest-Rising STD
Syphilis ranks third in total reported cases but has been the most alarming trend in recent years. Cases surged 42% between 2020 and 2024, though 2024 provisional data shows the first significant reversal: primary and secondary syphilis dropped 22% compared to 2023.
Syphilis progresses through distinct stages if untreated. The first sign is usually a painless sore (called a chancre) at the site of infection, which heals on its own after a few weeks. This is deceptive, because the infection hasn’t gone away. The second stage can bring rashes, fever, swollen lymph nodes, and fatigue. If still untreated, syphilis enters a latent phase with no symptoms that can last years before eventually damaging the heart, brain, and other organs.
Syphilis during pregnancy is especially dangerous. It can pass to the baby and cause stillbirth, severe birth defects, or infant death. This is why screening at the first prenatal visit is standard, with repeat testing later in pregnancy for those at higher risk.
Like chlamydia, syphilis is curable with antibiotics when caught early. But because its initial sore is painless and often hidden, many people miss it entirely.
Who Should Get Tested and How Often
Screening recommendations vary by age, sex, and sexual behavior. For chlamydia and gonorrhea, annual testing is recommended for all sexually active women under 25. Women 25 and older should be tested if they have risk factors such as a new partner or multiple partners. Men who have sex with men should be screened at least annually for all three infections, and every 3 to 6 months if they have multiple partners or are on HIV prevention medication.
For syphilis, screening targets people at increased risk based on factors like geography, history of incarceration, or substance use. All pregnant women should be tested at the first prenatal visit regardless of risk level.
People living with HIV are recommended to be screened for all three infections at their first evaluation and at least once a year after that, with more frequent testing based on individual risk.
How Condoms Reduce Risk
Latex condoms, used consistently and correctly, are highly effective at reducing transmission of infections spread through genital secretions, including chlamydia, gonorrhea, and trichomoniasis. For syphilis, condoms offer more limited protection because the sore can appear on skin not covered by the condom. The same applies to herpes and HPV, which spread through skin-to-skin contact.
Condoms remain one of the most practical tools for reducing STD risk, but they work best as part of a broader approach that includes regular screening, prompt treatment, and open communication with sexual partners. Since all three of the most common STDs can be present without symptoms, testing is the only reliable way to know your status.