Silent STIs: When There Are No Symptoms

It’s time for the hard truth—when it comes to sexually transmitted infections (STIs), what you don't know can hurt you. Many of us think we'd definitely notice if something was wrong "down there," but the truth is far more complicated. Some of the most common STIs can silently hang out in your body without causing a single noticeable symptom, potentially causing harm or being passed to partners without your knowledge.

So, we’ve provided you with this guide into the surprisingly common world of asymptomatic STIs—what they are, why they matter, and how to protect yourself when your body isn't giving you obvious warning signs.

The Silent Majority: How Common Are Asymptomatic STIs?

If you think most STIs announce themselves with obvious symptoms, the statistics might surprise you:

The numbers are truly eye-opening. According to the Center for Disease Control (CDC), over 2.4 million cases of sexually transmitted infections (STIs) were diagnosed and reported in 2023 alone, including over 1.6 million cases of chlamydia, 600,000 cases of gonorrhea, and 209,000 cases of syphilis. This includes 3,882 cases of congenital syphilis with 279 stillbirths and infant deaths.

But here's what's particularly alarming: these numbers only represent the infections that were actually diagnosed. The truth is that millions more people are carrying STIs without any idea they're infected.

Why So Many STIs Fly Under the Radar

The primary reason STIs often go undetected is simple: many don't cause noticeable symptoms. Research from the National Institute of Health confirms this silent epidemic:

Chlamydia: Studies across five countries found that between 31.2% to 100% of those with chlamydia reported no symptoms at all. This infection is particularly sneaky, as it can exist for months or even years without detection.
Gonorrhea: Similarly, about 66.7% to 100% of those with gonorrhea reported no symptoms in the same international study. When left untreated, it can lead to serious reproductive complications.
Herpes: As many as 90% of people with HSV-2 (genital herpes) are unaware they have the virus, according to data from the CDC. The virus can remain dormant for extended periods.
Trichomoniasis: Over 80% of trichomoniasis cases are asymptomatic, yet this infection affects millions worldwide annually.

The World Health Organization (WHO) confirms that more than 1 million curable STIs are acquired every day worldwide in people aged 15-49, with the majority being asymptomatic.

How Long Can You Have an STI Without Knowing?

The timeline for how long you can carry an STI without symptoms varies dramatically depending on the infection:

Chlamydia and Gonorrhea: These bacterial infections can remain asymptomatic for months or even years. Without testing, you may never know you're infected until complications arise, like pelvic inflammatory disease or infertility.
Herpes: It's possible to have herpes without knowing it for a long time, even up to 30 years. The virus can remain dormant in nerve cells, occasionally reactivating and causing outbreaks—but some people never experience symptoms at all.
HIV: A person can be HIV-positive for up to 10 years without showing significant symptoms, though they can still transmit the virus during this period.
HPV: Human papillomavirus can remain in the body for years without causing any noticeable symptoms, potentially leading to cervical cancer or other complications if certain high-risk strains are present.

The Dangers of Asymptomatic STIs

When STIs go undetected, they pose serious risks:

Continued transmission: You might unknowingly pass the infection to partners during periods when you have no symptoms.
Long-term health complications: Left untreated, STIs like chlamydia and gonorrhea can lead to pelvic inflammatory disease, which is a leading cause of preventable infertility.
Increased vulnerability to other infections: Having one untreated STI can make you more susceptible to contracting others, including HIV.
Pregnancy complications: Undiagnosed STIs can lead to premature birth, low birth weight, or transmission to newborns during delivery.

When Should You Get Tested?

Since symptoms aren't a reliable indicator of infection, regular testing is essential, especially if:

You have a new sexual partner
You have multiple partners
Your partner has other partners
You're planning to become pregnant
You notice unusual symptoms, even mild ones
Your partner has been diagnosed with an STI

The CDC recommends that sexually active women under 25 get tested for chlamydia and gonorrhea annually, as well as older women with new or multiple sex partners. Men who have sex with men should be tested at least once a year for all STIs, and more frequently based on sexual practices.

The Silent Nature of Specific STIs

Chlamydia: The "Silent Infection"

Chlamydia has earned its nickname as the "silent infection" because it rarely announces its presence. When symptoms do appear, they're often mild and easily confused with other conditions like urinary tract infections or yeast infections.

Women might notice:

Abnormal vaginal discharge
Burning when urinating
Light bleeding between periods

Men might experience:

Clear or whitish discharge from the penis
Burning or itching around the opening of the penis
Pain and swelling in one or both testicles (less common)

But remember—most people don't notice any symptoms at all.

Herpes: More Than Just Outbreaks

While herpes is often associated with visible sores, many people with HSV (both type 1 and type 2) never develop the classic blisters or have such mild symptoms they don't recognize them as herpes.

Your first herpes outbreak can happen anywhere from 2 to 20 days after infection, but for many people, the virus remains dormant much longer. Some may experience their first outbreak years after initial exposure, often triggered by stress, illness, or changes in the immune system.

Even between visible outbreaks, herpes can still be transmitted through a process called "asymptomatic viral shedding"—when the virus is active on the skin's surface without causing symptoms.

HPV: The Common Invisible Infection

Human papillomavirus (HPV) is the most common STI in the U.S., and most sexually active people will contract at least one type during their lifetime. Most HPV infections cause no symptoms and clear on their own—but some high-risk types can lead to cervical cancer and other cancers if they persist.

Since there's no good way to test for HPV in men, and testing isn't routinely recommended for women under 30, many people never know they have it until related complications arise.

Testing Options When You Have No Symptoms

If you're sexually active but don't have symptoms, several testing options are available:

Urine tests: Simple and non-invasive tests for chlamydia and gonorrhea.
Blood tests: Can detect antibodies for herpes, syphilis, and HIV.
Swab tests: For more accurate diagnosis of certain infections, particularly at specific sites like the throat or rectum.
Cervical screening: Pap smears can detect HPV-related cell changes that might lead to cervical cancer.

At Twentyeight Health, we offer discreet STI testing with at-home collection kits for many common infections, making it easier than ever to stay on top of your sexual health without waiting until symptoms appear.

Prevention Is Better Than Treatment

While regular testing is essential, preventing STIs in the first place is always preferable. Effective prevention strategies include:

Using condoms consistently and correctly
Limiting your number of sexual partners
Being in a mutually monogamous relationship with an uninfected partner
Getting vaccinated against HPV and hepatitis B
Talking openly with partners about sexual health and testing
Considering pre-exposure prophylaxis (PrEP) if you're at high risk for HIV

Taking Action: Your Next Steps

If you've been sexually active and haven't been tested recently—even if you feel perfectly healthy—consider scheduling an STI screening. At Twentyeight Health, we make testing simple, private, and judgment-free.

Remember that most STIs are easily treatable when caught early, and even those that can't be cured (like herpes and HIV) can be effectively managed with proper medication.

Your sexual health is an important part of your overall wellbeing. Don't let the silent nature of STIs keep you from getting the care you deserve.

It’s never too late – or too early – to take control of your sexual health? Connect with a Twentyeight Health provider today for confidential testing, treatment options, and supportive care that respects your privacy and meets you where you are.

This article was medically reviewed by Twentyeight Health's clinical team.

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Written with the participation of