Sexually transmitted infections: No symptoms, but still infected?

Sexually transmitted infections (STIs) are infections transmitted through sexual contact, such as chlamydia, gonorrhea, syphilis, or HIV. Many STIs can be asymptomatic, meaning a person may be infected without realizing it. Regular testing plays a crucial role in early detection and in preventing transmission. In this article, you’ll learn which STIs often present no symptoms, when you should get tested, and how to prevent an STI.

Table of Contents

• What are sexually transmitted infections (STIs)?
• Can I have an STI without showing symptoms?
• Are STIs contagious if there are no symptoms?
• Should I get tested for an STI even if I have no symptoms?
• How are sexually transmitted infections diagnosed?
• Can an STI go away on its own?
• What are the risks of untreated asymptomatic STIs?
• Summary

What are sexually transmitted infections (STIs)?

Sexually transmitted infections (STIs) are infections primarily transmitted through sexual contact, including vaginal, oral, or anal sex, as well as through intimate skin-to-skin contact or the sharing of sex toys. They are caused by bacteria, viruses, or parasites. The most well-known STIs include chlamydia, gonorrhea, syphilis, HIV, herpes, trichomoniasis, and HPV (Cleveland Clinic, 2023). 

Can I have an STI without showing symptoms?

Yes, many STIs are asymptomatic (especially in the early stages) or present only mild symptoms that may go unnoticed or not be taken seriously (NHS, 2024).

Which STIs are often asymptomatic?

STIs that are frequently asymptomatic include chlamydia, gonorrhea, HIV, genital herpes, syphilis, and human papillomavirus (HPV).

Chlamydia

Chlamydia is a sexually transmitted infection caused by the bacterium Chlamydia trachomatis. About 70% of infections in women and 50% in men are asymptomatic. If symptoms do occur, they may include discharge, burning during urination, itching, and an unpleasant odor. Transmission occurs through unprotected vaginal, anal, or oral sex, or direct mucosal contact (WHO, 2023).

Gonorrhea

Gonorrhea is an STI caused by the bacterium Neisseria gonorrhoeae. Among women, 65–86% of infections are asymptomatic; among men, 15–55% show no symptoms. If symptoms occur, they typically include discharge, pain during urination, and abdominal pain. Transmission also occurs through unprotected vaginal, anal, or oral sex (NHS, 2021).

HIV (Human Immunodeficiency Virus)

HIV is a virus that weakens the immune system and can lead to AIDS if left untreated. The asymptomatic period varies from person to person and can last up to 10 years. When symptoms do occur, they are usually non-specific, such as flu-like symptoms. HIV is transmitted through the exchange of bodily fluids such as blood, semen, vaginal secretions, or breast milk—commonly through unprotected sex, blood contact, or shared needles (NHS, 2021). 

HPV (Human Papillomavirus)

HPV is a widespread infection with over 100 virus types. Most infections are asymptomatic and clear within two years without treatment. Some types (low-risk) cause visible symptoms like genital warts, while others (high-risk) significantly increase the risk of cancer, especially cervical cancer, but also rarely cause symptoms. HPV is transmitted through intimate skin-to-skin contact during vaginal, oral, or anal sex (even without penetration). Infection is possible even without visible symptoms (Cleveland Clinic, 2022).

Herpes

Herpes is a viral infection caused by herpes simplex viruses (HSV). There are two main types: HSV-1, primarily causing oral herpes, and HSV-2, responsible for genital herpes. 75–90% of those infected are unaware, as they either experience no symptoms or only mild, barely noticeable ones. Symptoms include painful blisters, redness, itching, and tingling around the lips or genitals. Herpes is transmitted through direct skin-to-skin contact during vaginal, anal, or oral sex, especially when in contact with blisters or infected mucous membranes. Infection can occur even without visible symptoms (Cleveland Clinic, 2023).

Syphilis

Syphilis is caused by the bacterium Treponema pallidum and often goes unnoticed due to symptom-free phases. Around 50% of those infected show no symptoms. If symptoms occur, they may include painless sores, rashes, or mild fever—often overlooked because they are non-specific and resemble other conditions. Transmission occurs through unprotected vaginal, anal, or oral sex, direct contact with syphilis sores, or blood transfusions. Syphilis can also be transmitted from mother to child during pregnancy (WHO, 2024).

Are STIs contagious if there are no symptoms?

Yes, STIs can be contagious even without symptoms. The incubation period refers to the time between infection and the onset of symptoms. This period varies greatly among STIs: chlamydia 1–3 weeks, gonorrhea 2–14 days, HIV 2–4 weeks. Many STIs, including chlamydia, gonorrhea, HIV, herpes, and syphilis, are contagious during the incubation period. If symptoms don’t appear after this period, the infection may still be transmitted unknowingly unless preventive measures are taken (NHS, 2024).

How can STIs be effectively prevented?

To prevent STIs or their unintended transmission, always use a condom during vaginal, anal, and oral sex and get tested regularly—especially before new relationships, with multiple partners, or after unprotected sex. Vaccinations, such as those against high-risk HPV types, are also recommended. Open and honest communication with your partner about sexual health helps protect you both and supports joint testing and treatment if needed. Avoid intimate contact during active symptoms (NHS, 2023). 

Should I get tested for an STI even if I have no symptoms?

Yes, even without symptoms, you should get tested for STIs, especially:

• After unprotected sex (vaginal, oral, anal)

• With frequently changing sexual partners

• Before starting a new sexual relationship

• If you have symptoms such as discharge or burning

• If your partner tested positive for an STI

• After experiencing sexual assault

• As part of prenatal care

Source: MedlinePlus, 2024

You’re not sure which STIs to test for and prefer not to visit a doctor? Homed-IQ’s STI Test Guide can help you find the right test.

How are sexually transmitted infections diagnosed?

STIs can be diagnosed through blood tests, urine samples, or swabs from affected areas, depending on the type of infection. Symptoms are also considered in the diagnosis. STI testing is essential to detect infections, prevent long-term consequences, and avoid spreading the infection. In Germany, STI tests are available through general practitioners, gynecologists, urologists, public health offices, or specialized clinics (WHO, 2024). For more detailed information, read our blog: How is an STI test performed?

The diagnostic window refers to the time between infection and the point when a test can reliably detect the infection. Adhering to the diagnostic window is crucial, as testing too early can result in false negatives due to insufficient viral or bacterial load.

Source: NHS, 2023

Want to get an overview for yourself?

Regular STI testing is especially important if you have multiple sexual partners, are starting a new relationship, or had unprotected sex. Testing is also useful if you notice unusual symptoms or simply want clarity about your sexual health. Homed-IQ’s home testing kits—like the chlamydia and gonorrhea test, the complete STI test, or the HPV test—allow you to discreetly test for individual infections or multiple STIs. Learn more in our blog post: When should you get tested for STIs?

Can an STI go away on its own?

Some STIs, like HPV and occasionally genital herpes, may be cleared by the immune system without treatment. However, relying on this is risky, as complications may arise and the infection can be transmitted to partners. Regular testing is essential to detect infections and confirm healing. In Germany, HPV screenings are part of cancer prevention programs; women over 20 are eligible for annual Pap smears, and from age 35, a combination of Pap and HPV testing is offered every three years (BMG, 2024).

What are the risks of untreated asymptomatic STIs?

Untreated, asymptomatic STIs can lead to serious health issues, including infertility and pregnancy complications (e.g., from chlamydia and gonorrhea), chronic pain such as pelvic inflammatory disease, and permanent organ or nerve damage (e.g., from syphilis). The risk of HIV infection also increases, as damaged mucous membranes are more vulnerable. If left untreated, HPV can lead to cancers, particularly cervical cancer—95% of cervical cancer cases are caused by persistent infections with high-risk HPV types (WHO, 2024). There is also the risk of unknowingly infecting sexual partners.

Summary

Sexually transmitted infections (STIs) are often asymptomatic—especially chlamydia, gonorrhea, HIV, herpes, syphilis, and HPV—but still contagious and may be unknowingly passed on. Regular testing is essential for early detection, preventing transmission, and avoiding long-term consequences. Preventive measures include frequent testing, condom use, vaccination, and open communication about sexual health.