The most common sexually transmitted diseases in the United States are chlamydia, gonorrhea, syphilis, human papillomavirus (HPV), herpes (HSV-1 and HSV-2), trichomoniasis, HIV, and hepatitis B. In 2024 alone, over 2.2 million cases of just chlamydia, gonorrhea, and syphilis were reported to the CDC, and those are only the infections that get diagnosed. Many STDs produce no symptoms at all, meaning the true numbers are significantly higher.
Chlamydia
Chlamydia is the most frequently reported STD in the country, with roughly 1.5 million cases documented in 2024. It’s caused by bacteria and is one of the easiest infections to miss because it’s commonly asymptomatic in both men and women. When symptoms do appear, women may notice pelvic or abdominal pain, while men may experience testicular pain. Left untreated, about 10 to 15 percent of women with chlamydia will develop pelvic inflammatory disease (PID), which can cause chronic pain and infertility.
Chlamydia is curable with a short course of antibiotics. Because reinfection is common, guidelines recommend retesting about three months after treatment. Routine screening is recommended for all sexually active women under 25, and for older women with risk factors like new or multiple partners.
Gonorrhea
Gonorrhea is the second most reported STD, with over 543,000 cases in 2024. Like chlamydia, it’s bacterial and often shows no symptoms, particularly in women. When it does cause problems, the signs overlap with chlamydia: discharge, pain during urination, and pelvic discomfort. Gonorrhea can also infect the throat and rectum.
The major concern with gonorrhea is antibiotic resistance. Treatment options have narrowed over the years as the bacteria have evolved, making it important to get tested and treated promptly rather than relying on leftover medications. Screening recommendations mirror those for chlamydia, and retesting three months after treatment is also advised.
Syphilis
Syphilis has surged in recent years and is now a growing public health concern. Over 190,000 total syphilis cases were reported in 2024, including nearly 4,000 cases of congenital syphilis (passed from mother to baby during pregnancy).
Syphilis progresses through distinct stages. The first stage typically produces a single painless sore, called a chancre, at the site of infection. Because it doesn’t hurt, many people miss it entirely. The second stage can bring a body rash, sores in the mouth or genital area, and swollen lymph nodes. If still untreated years later, tertiary syphilis can damage the heart, brain, and other organs. The good news is that syphilis is curable at every stage, though damage from later stages can be permanent.
Human Papillomavirus (HPV)
HPV is the most common STD overall when you account for undiagnosed infections. Most sexually active people will contract at least one strain of HPV at some point. The majority of infections clear on their own and never cause problems, but certain high-risk strains are responsible for more than 90 percent of cervical cancers, along with cancers of the throat, anus, and genitals.
The HPV vaccine protects against nine strains that together prevent about 90 percent of cervical cancers. It’s recommended for preteens but can be given through age 26, and in some cases up to 45. Routine Pap smears and HPV tests for women help catch precancerous changes early, well before they progress.
Herpes (HSV-1 and HSV-2)
Herpes is extremely widespread. An estimated 3.8 billion people under age 50 worldwide carry HSV-1, which is roughly 64 percent of the global population. HSV-1 primarily causes oral herpes (cold sores) and spreads through contact with sores, saliva, or skin around the mouth. It can also be transmitted to the genitals through oral sex.
HSV-2, the type more commonly associated with genital herpes, affects an estimated 520 million people aged 15 to 49 globally. It spreads through sexual contact with genital or anal surfaces, skin, sores, or fluids. Both types are lifelong infections. Outbreaks tend to become less frequent over time, and antiviral medications can reduce the severity and frequency of flare-ups as well as lower the risk of passing it to a partner. Many people with herpes have mild or no symptoms and don’t realize they’re infected.
Trichomoniasis
Trichomoniasis is caused by a parasite rather than bacteria or a virus, making it unique among common STDs. Globally, there were an estimated 156 million new cases in 2020 among people aged 15 to 49. Women may experience vaginal discharge that can look yellowish or greenish, itching, pain during urination, and discomfort during sex. Most men with trichomoniasis have no symptoms at all, though some notice penile discharge or irritation.
Trichomoniasis is curable with a single dose of oral medication, and both partners need treatment at the same time to avoid passing the infection back and forth.
HIV
HIV attacks the immune system and, without treatment, progresses to AIDS. Early symptoms can resemble the flu, appearing two to four weeks after infection, and then the virus can remain silent for years while it gradually weakens the body’s defenses.
Modern treatment has transformed HIV from a fatal diagnosis into a manageable chronic condition. People on effective treatment can reach an undetectable viral load, meaning they cannot sexually transmit the virus. For people who are HIV-negative but at elevated risk, PrEP (pre-exposure prophylaxis) is a daily or on-demand medication that greatly reduces the chance of getting HIV. PrEP pills reach maximum protection for receptive anal sex after about 7 days of daily use, and for vaginal sex or injection drug use after about 21 days. Screening is recommended for all adults aged 13 to 64 at least once, with more frequent testing for those at higher risk.
Hepatitis B
Hepatitis B is a viral infection that attacks the liver and can spread through sexual contact, shared needles, or from mother to child during birth. Most adults who contract it clear the virus on their own, but about 5 to 10 percent develop a chronic infection that can lead to liver damage, cirrhosis, or liver cancer over time.
Vaccination is the most effective form of prevention. Current recommendations call for hepatitis B vaccination for all infants, unvaccinated children under 19, and all adults aged 19 to 59. Adults 60 and older with risk factors should also be vaccinated. If you were born before routine infant vaccination became standard and aren’t sure of your status, your doctor can check with a simple blood test.
Who Should Get Tested
Because so many STDs are asymptomatic, testing is the only reliable way to know your status. General guidelines recommend that all sexually active women under 25 get screened for chlamydia and gonorrhea annually. Women 25 and older should be screened if they have a new partner, multiple partners, a partner who has other partners, or inconsistent condom use. Men who have sex with men are advised to test for syphilis, chlamydia, gonorrhea, and HIV at least once a year, and every three to six months if at higher risk.
Everyone between the ages of 13 and 64 should be tested for HIV at least once in their lifetime. All adults over 18 should be screened for hepatitis C at least once. These aren’t tests reserved for people with symptoms or concerns. They’re part of routine health maintenance, no different from blood pressure checks or cholesterol panels.