Sexually transmitted diseases (STDs), also called sexually transmitted infections (STIs), affect millions of people every year. While people of any age can get an STD, research consistently shows that certain age groups carry a much higher burden of infection — largely due to biological, behavioral, and social factors.

Here’s a clear breakdown of who has the highest STD rates and why.

Age Groups With the Highest STD Rates

Teens and Young Adults (Ages 15–24) — Highest overall rates

This group consistently has the highest STD rates in the United States, but that’s not the end of the story.

• Young people aged 15–24 account for about half of all new STD infections each year, even though they represent only about one-quarter of the sexually active population.
• Reported infections such as chlamydia and gonorrhea are especially high among adolescents and young adults.
• Overall data also show that sexually active youth have higher infection rates than any other age group.

Some analyses broaden the high-risk range slightly, showing that young adults aged 20–34 also experience very high infection rates, particularly as they remain highly sexually active.

Older Adults (Ages 55+ and especially 65+) — Fastest growing rates

While not the highest overall, this group is experiencing the most rapid increase in STD diagnoses.

• STD diagnoses among people 65 and older have risen sharply in recent years, with infections such as chlamydia, gonorrhea, and syphilis increasing several-fold over the past decade.
• From 2020–2023, adults 65+ had the largest percentage increase in STD diagnoses compared with any other age group.

Why Young People Have the Highest STD Rates

1. Higher-Risk Sexual Behaviors

Young people are statistically more likely to:

• Have multiple or new sexual partners
• Engage in unprotected sex
• Combine sex with alcohol or drug use

These behaviors significantly increase exposure to STDs.

2. Less Consistent Condom Use

While awareness of HIV prevention has improved, protection against bacterial STDs may be overlooked, contributing to rising infection rates.

From our partner

Join a Study, Help Future Patients. Researchers are studying a potential treatment for HER2+ metastatic breast cancer. Find out if you may qualify

3. Limited Sexual Health Knowledge

Adolescents may have less experience negotiating condom use or discussing sexual health with partners, which can increase risk.

4. Biological Vulnerability

Young women in particular can be more biologically susceptible due to cervical development changes that make infection easier.

5. Asymptomatic Infections

Many STDs (like chlamydia) often show no symptoms, leading to delayed testing and ongoing transmission.

Why STD Rates Are Rising Among Older Adults

1. Longer, Healthier Sex Lives

People are staying sexually active longer thanks to better overall health and medications that support sexual function.

2. Lower Condom Use

Older adults are less likely to use condoms, partly because pregnancy is no longer a concern.

3. Less STI Education

Many older adults grew up before modern sexual health education and may not fully understand STD risks or testing recommendations.

From our partner

Diagnosed with Advanced Small Cell Lung Cancer? Learn more about a new study for patients with ES-SCLC.

4. Physiological Changes

Post-menopausal changes such as vaginal thinning can increase susceptibility to infection.

Most Common STDs by Age Group

Sexually transmitted diseases (STDs) don’t affect all age groups the same way. Certain infections are much more common at specific stages of life due to differences in sexual behavior, biology, testing rates, and prevention practices.

Here’s a clear breakdown of which STDs are most common by age group.

Ages 15–19

Most Common STDs:

• Chlamydia
• Human Papillomavirus (HPV)
• Gonorrhea

Why these are common:

• New sexual activity and multiple partners
• Lower condom consistency
• High biological susceptibility (especially cervical vulnerability in teen girls)
• Many infections are asymptomatic, so they spread unnoticed

Chlamydia is by far the most diagnosed STD in teenage girls, largely because of routine screening recommendations in this group.

Ages 20–24

Most Common STDs:

• Chlamydia (still the #1 infection)
• Gonorrhea
• Herpes Simplex Virus
• Human Papillomavirus

Why these are common:

• Peak sexual activity years
• Dating apps / new partner turnover
• Less frequent routine healthcare visits after leaving pediatric care
• Alcohol or substance use affecting decision-making

Gonorrhea rates are highest in this age range, especially in urban areas.

Ages 25–34

Most Common STDs:

• Chlamydia
• Gonorrhea
• Syphilis (notably rising)
• Human Immunodeficiency Virus (HIV)

Why these are common:

• Continued high sexual activity
• Relationship transitions (dating → marriage → divorce → new partners)
• Lower perceived risk compared with younger years
• In some populations, increased exposure within sexual networks

Syphilis rates have surged in adults under 35 in recent years, including congenital syphilis cases linked to untreated infections.

Ages 35–44

Most Common STDs:

• Trichomoniasis
• Herpes Simplex Virus
• Human Immunodeficiency Virus

Why these are common:

• Divorce or re-entering the dating pool
• Lower condom use due to reduced pregnancy concerns
• Long-standing herpes infections becoming symptomatic
• Less frequent routine STD screening

Trichomoniasis is often underdiagnosed but becomes more common in women over 30.

Ages 45–64

Most Common STDs:

• Herpes Simplex Virus
• Syphilis (increasing)
• Gonorrhea (rising trend)

Why these are common:

• New relationships after divorce or widowhood
• Erectile-dysfunction medications enabling continued sexual activity
• Lower condom use
• Limited sexual health education growing up

Many diagnoses occur later because symptoms are mistaken for aging-related health issues.

Ages 65+

Most Common STDs:

• Syphilis
• Gonorrhea
• Chlamydia (rapid increase from a low baseline)

Why these are increasing:

• Longer life expectancy and active sex lives
• Condom use is lowest in this group
• Physiological changes (vaginal thinning, immune changes)
• Doctors may not routinely screen older adults

This group has the fastest growth rate of STD diagnoses, even though total numbers are still lower than in young adults.