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Many sexually transmitted infections (STIs) such as chlamydia, gonorrhea, or HIV often go unnoticed at first – even when an infection has already occurred. If you want certainty after a potential risk exposure, testing is essential. However, the timing of an STI test is crucial: if testing is done too early, an infection may be missed even though it is already present.
In this article, you will learn what the so-called window period (also called the diagnostic window) means, when different STIs can be reliably detected through testing, and the role the type of test plays.
Table of contents
- What does the window period mean in STI testing?
- When can STIs be reliably detected?
- What is the difference between incubation period and window period (diagnostic window)?
- FAQ: Frequently asked questions
What does the window period mean in STI testing?
The window period – also known as the diagnostic window – refers to the time between contracting a sexually transmitted infection and the point at which it can be reliably identified by a test.
During this phase, the pathogen may already be active in the body and transmissible, but still undetectable in a test. A negative result in this period therefore does not necessarily mean there is no infection – only that the pathogen may not yet be detectable.
When can STIs be reliably detected?
Window periods vary depending on the infection. The following overview shows when different STIs can be reliably identified through testing. The relevant window periods for each STI are based on NHG guidelines, which are also followed by our partner laboratory.
Important: Do not test too early, as a negative result during the window period may not yet be reliable.
| Infection | Detectable from | Recommended testing time |
|---|---|---|
| Chlamydia | approx. 1–2 weeks | from day 14 |
| Gonorrhea | approx. 1–2 weeks | from day 14 |
| Mycoplasma genitalium | approx. 2 weeks | from day 14 |
| Trichomoniasis | approx. 4 weeks | after 1 month |
| Syphilis | 3–6 weeks | from week 3 (if negative, repeat at week 12) |
| HIV (antibody/antigen test) | from 2 weeks, more reliable after 6 weeks | from week 6 (if negative, repeat at week 12) |
| Hepatitis B | 4–10 weeks | from week 6–8 (if negative, repeat after 3–6 months) |
Herpes (HSV-1 / HSV-2) can usually only be reliably detected when blisters or fresh skin lesions are present, as a PCR swab test is most accurate at that time.
Human papillomavirus (HPV) does not have a defined window period like other STIs. It is usually identified through a cervical swab (HPV DNA test or Pap test). Since HPV infections are often symptomless and frequently clear up on their own, testing is primarily recommended as part of routine screening programs.
Which factors influence the window period?
The window period can vary depending on the pathogen, the testing method, and the immune response. For this reason, high-quality laboratory tests are particularly important – always check the information provided with your test, or seek medical advice if you are unsure.
Why is the right timing for testing so important?
Testing too early can lead to a false-negative result. The pathogen may already be in the body but not yet detectable – creating a false sense of security.
That’s why it’s important to know the window period, repeat the test after a few weeks if in doubt, and seek medical advice if you have symptoms, a high-risk exposure, or significant uncertainty.
What is the difference between incubation period and window period (diagnostic window)?
These terms are often confused, but they mean different things:
- Incubation period = the time between infection and the appearance of first symptoms.
- Window period / diagnostic window = the time between infection and the point at which the infection can be reliably detected by a test.
Important: Many STIs remain symptomless. Even without any complaints, an infection may still be present. Only a test taken after the window period provides reliable results (Cleveland Clinic, 2024).
Testing for STIs easily at home
With Homed-IQ home tests, you can test yourself for STIs easily, discreetly, and reliably – without needing a doctor’s appointment. The sample is collected conveniently at home and analyzed in a certified laboratory. Your results will be available online within a few days – secure and confidential.
FAQ: Frequently asked questions
I had unprotected sex yesterday – should I get tested right away?
Testing the next day is usually too early, as the pathogens are not yet detectable. It’s best to wait for the recommended window period (see table). If you’re worried, consult a doctor – in certain cases, immediate post-exposure prophylaxis (PEP, e.g., for HIV) may be recommended.
Can I still be contagious even if my test result is negative?
Yes. During the window period, an infection may not show up in a test but can still be transmitted. That’s why you should use protection until you have a reliable result.
What should I do if I have symptoms but my test is negative?
If you develop symptoms such as discharge, burning during urination, or skin changes, you should seek medical advice even if your test result is negative.
References
Het soa-consult. (n.d.). NHG-Richtlijnen. Retrieved August 19, 2025, from https://richtlijnen.nhg.org/standaarden/het-soa-consult#volledige-tekst
Incubation Period (Incubation Time) of Infections & Diseases. (2024, June 25). Cleveland Clinic. Retrieved August 19, 2025, from https://my.clevelandclinic.org/health/articles/incubation-period
Sexually transmitted infections (STIs). (2023, September 27). Newcastle Hospitals NHS Foundation Trust. Retrieved August 19, 2025, from https://www.newcastle-hospitals.nhs.uk/services/sexual-health/sti-screening/
