Negative STI test but still symptoms? 7 explanations

Your STI test came back negative and your symptoms have not stopped. That usually has one of three causes: you tested too early, the sample was taken somewhere other than where the infection sits, or the symptoms are not from an STI at all.

At the Dutch Centres for Sexual Health, 16.7 per cent of all tests were positive in the first half of 2025 (RIVM). Negative is the ordinary result, including for people with symptoms.

What strikes me about the questions we get on this: many people read negative as "so it is all in my head". It rarely is.

These are the seven explanations we run into most often.

1. You tested too early
2. Nobody sampled the site where the infection sits
3. Mycoplasma genitalium is not in a standard STI test
4. Herpes and HPV are rarely found by an ordinary STI test
5. Pubic lice and scabies are seen, not tested
6. Your symptoms are not from an STI
7. You were treated and reinfected

Why is my STI test negative while I have symptoms?

A negative STI test with ongoing symptoms usually points to timing, site or panel. You may have tested before the infection was measurable, at a site that was never sampled, or only for the pathogens a standard panel covers. On top of that, the same symptoms can come from something that is not an STI.

Those four tracks do not exclude each other. Together they explain almost every negative result where the symptoms carry on.

1. You tested too early

Every STI has a stretch where the infection is present but not yet measurable, the window period. Test inside it and the result can read negative while something is going on. For chlamydia and gonorrhoea that stretch runs about two weeks.

For HIV a result is indicative after four weeks and only definitive after twelve. Syphilis sits in between, at roughly six weeks.

Say two people get a negative chlamydia result on the same day, one 4 days after the risk and the other 5 weeks after. Only the second has cleared the window period by a wide margin. At 4 days the test says almost nothing, however reassuring the word negative looks.

That first result says more about the calendar than about the person.

We set it out per infection in how long after unprotected sex you can test.

2. Nobody sampled the site where the infection sits

Chlamydia and gonorrhoea can sit in the throat or the anus without urine or a vaginal swab picking them up. If only the urogenital site is sampled, that infection stays invisible. This is a cause that is easy to overlook.

Researchers followed 13,476 visitors to a sexual health clinic in Los Angeles. Over 80 per cent of rectal and pharyngeal chlamydia, and over 65 per cent of rectal and pharyngeal gonorrhoea, would have been missed on urogenital testing alone (Assaf and colleagues, 2022).

That is not a detail.

If you have had oral or anal sex and feel symptoms there, a urine test says little about it. How a throat swab works is covered in testing for an STI in the throat.

3. Mycoplasma genitalium is not in a standard STI test

Mycoplasma genitalium is a bacterium that can cause symptoms resembling chlamydia: burning when you urinate, discharge and irritation. Most standard panels do not test for it, because it needs its own PCR. Your result is then negative for everything that was tested.

In a meta-analysis by Baumann and colleagues, mycoplasma genitalium was found in about 1.3 per cent of the general population in higher-income countries (2018). Among men with urethritis and no detectable chlamydia, that share runs clearly higher.

This is the pathogen that comes up most in questions about stubborn symptoms after a clean result. There is more on it in the STI a standard test does not measure.

4. Herpes and HPV are rarely found by an ordinary STI test

Genital herpes and HPV are usually not part of a blood or urine STI panel. Herpes is normally identified with a PCR from a blister during an outbreak. HPV usually shows up because a doctor looks at visible warts.

Without symptoms at the moment of testing, there is little to find. That explains a recurring misunderstanding: someone gets checked for everything, gets a negative result, and concludes herpes is ruled out. That does not follow.

We work it through in is HPV an STI and in what a herpes test does and does not tell you.

5. Pubic lice and scabies are seen, not tested

Pubic lice and scabies are sexually transmissible, but no STI panel carries a lab test for them. They are identified by looking. Pubic lice cause itching in the pubic hair, and you can sometimes see the lice or their eggs yourself.

Scabies causes itching that often worsens at night, with fine burrows in the skin between the fingers, at the wrists or around the genitals. Both are harmless and usually treatable with a product from the pharmacy or the GP.

A negative STI test does not rule them out. I put them on this list deliberately, because you can look for these yourself without another blood draw. With ongoing itching, a look from a doctor may do more than a second blood test.

Other causes of itching are covered in itching and irritation down there.

6. Your symptoms are not from an STI

Burning urination, discharge, itching and irritation belong to STIs, but just as much to conditions that have nothing to do with sex. A urinary tract infection, bacterial vaginosis, candida or an irritated glans can cause similar symptoms. A negative STI test is then pointing the right way.

Bacterial vaginosis is a common cause of changed discharge and is not an STI. Shaving, a new detergent or tight trousers can also cause irritation that lasts for days.

You can tell them apart in bacterial vaginosis, candida or trichomonas, in STI or urinary tract infection and, for men, in balanitis.

7. You were treated and reinfected

If symptoms came back after treatment, reinfection is one of the first things to consider. A partner who was not treated can pass the infection back at the next contact. The treatment worked, the exposure did not stop.

There is something else at play. Symptoms can carry on for weeks after successful treatment while the bacterium is already gone, because the tissue needs time to recover. A negative follow-up test is then a good sign, not a contradiction.

When a retest can make sense is covered in chlamydia retest and follow-up after treatment. We wrote a separate piece on the conversation with your partner.

What does a standard STI test measure, and what does it miss?

A standard STI test usually looks at chlamydia, gonorrhoea, syphilis and HIV, and often trichomonas and hepatitis B as well. Herpes, HPV, mycoplasma genitalium, pubic lice and scabies are generally not included. Below you see per pathogen what a common panel picks up.

This table is exactly why I have trouble with the phrase full STI test. No panel covers everything, and that need not be a problem as long as you know what is in yours. Which test suits which situation is covered in our guide on which STI test you need and when.

What can you do if your symptoms continue?

If symptoms carry on after a negative result, there are roughly three routes. You can get checked again once the window period has passed. You can have the site where the risk happened sampled. And you can ask your GP to look at the causes outside the STIs.

What helps me here is taking the contact as my starting point. If you know the date, you know whether the window period has passed. If you know what kind of contact it was, you know which site needs sampling.

According to Thuisarts.nl, STIs regularly run without symptoms, which can make a test the only way to gain clarity (thuisarts.nl). The reverse holds just as often: symptoms without an STI are common.

Chlamydia, gonorrhoea and trichomonas can be checked in one go with the chlamydia, gonorrhoea and trichomonas check. If your symptoms do not fit those, discuss them with your GP.

Sources

• RIVM, Thermometer seksuele gezondheid, first half of 2025 (2025) (rivm.nl)
• Assaf RD, Cunningham NJ, Adamson PC, Jann JT, Bolan RK. High proportions of rectal and pharyngeal chlamydia and gonorrhoea cases among cisgender men are missed using current CDC screening recommendations. Sexually Transmitted Infections (2022). PMID 35217590
• Baumann L, Cina M, Egli-Gany D, Goutaki M, Halbeisen FS, Lohrer GR, Ali H, Scott P, Low N. Prevalence of Mycoplasma genitalium in different population groups: systematic review and meta-analysis. Sexually Transmitted Infections (2018). PMID 29440466
• Thuisarts.nl, Soa (2024) (thuisarts.nl)

Every blood test result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.