A negative STD test with ongoing symptoms usually points to one of a few things: you tested during the window period before the infection was detectable, the right body site wasn't sampled, the cause is a bacterium your panel didn't cover (like Mycoplasma genitalium), or it isn't an STI at all. A urinary tract infection or yeast can mimic the same signs. A repeat or broader test settles it.
Chlamydia trachomatis
Mycoplasma genitalium
Urethritis not caused by gonorrhea
| Item | Value |
|---|---|
| Chlamydia | curable — Chlamydia trachomatis |
| Mycoplasma genitalium | curable — Mycoplasma genitalium |
| Nongonococcal urethritis (NGU) | curable — Urethritis not caused by gonorrhea |
Why a negative test and real symptoms can both be true
A test answers a narrow question: was this specific organism present in this specific sample on this day? Symptoms answer a broader one: something is inflamed and bothering you. Those two questions don't always line up. Continuing symptoms after a negative result generally trace back to a test done within the window period before an infection became detectable, a body site that wasn't sampled (throat or rectum, for example), or a non-STI cause such as a UTI or yeast infection CDC STI Guidelines, 2021. Sometimes the culprit is a bacterium that wasn't on the panel you ordered. The infections below overlap too much to tell apart by sight, and several are frequently silent, so the result is what names the cause.
STIs that can cause continuing symptoms after a negative test
Chlamydia
Chlamydia is caused by the bacterium Chlamydia trachomatis, and most US genital infections come from serovars D–K. It's a quiet infection. Roughly three quarters of infected women and half of infected men have no symptoms at all CDC Chlamydia Fact Sheet. When symptoms do show, women may notice abnormal vaginal discharge and burning on urination; if it spreads upward it can cause lower abdominal or low-back pain, fever, pain during intercourse, and bleeding between periods. Symptoms, when they appear, usually do so within one to three weeks of exposure. A negative result here often means the test was taken too early or the wrong site was swabbed. A nucleic acid amplification test (NAAT) is the recommended method for both genital and extragenital infection. You can read more about the infection itself on our chlamydia overview.
Mycoplasma genitalium (M. gen)
Mycoplasma genitalium is a bacterium that lacks a cell wall, so beta-lactam antibiotics like penicillins and cephalosporins do nothing against it. It's an emerging cause of urethritis in men and cervicitis in women, and the central problem is antibiotic resistance, especially to macrolides. The tell-tale pattern is persistent or recurrent urethritis: discharge and painful urination that keep coming back even after treatment for something else. In women it can cause cervicitis that may progress to pelvic inflammatory disease (inflammation of the upper reproductive tract that can scar the fallopian tubes and threaten fertility), and it's frequently silent. M. gen is not on most standard STI panels, so an unremarkable negative chlamydia-and-gonorrhea result tells you nothing about it. An FDA-cleared NAAT on urine or a swab can detect it, and it should be considered in men with recurrent NGU and women with recurrent cervicitis CDC M. genitalium Guidance. Because resistance testing isn't commercially available in the US, awareness is key in mg diagnosis and treatment.
Nongonococcal urethritis (NGU)
NGU isn't a single germ. It's urethritis that isn't gonorrhea, a syndrome with several possible causes including Chlamydia trachomatis, Mycoplasma genitalium, sometimes Trichomonas, herpes simplex virus, or adenovirus. In about half of cases, no organism is ever identified. It mainly shows up in men as urethral discharge that can be mucoid or pus-like, painful urination, and urethral itching, though some infections cause nothing. So a negative gonorrhea-and-chlamydia panel can sit alongside real urethritis, with the inflammation present even when the named pathogens come back clear. Diagnosis relies on objective evidence of inflammation under the microscope or on a urine test, not just symptoms CDC Urethritis Guidance. People often wonder whether it clears up on its own — see can ngu go away on its own without treatment?.
When it's not an STI at all
A negative result that's actually accurate is common, and the discomfort still has to come from somewhere. The usual non-STI suspects:
- A urinary tract infection, which causes burning on urination, urgency, and frequency, and is bacterial but not sexually transmitted.
- A yeast infection, which produces itching, irritation, and a thick discharge in women, or irritation under the foreskin in men.
- Skin and mechanical irritation from soaps, spermicides, latex, or friction, which can mimic the burning and itching of an infection.
- Bacterial vaginosis, an imbalance of normal vaginal bacteria that causes discharge and odor and isn't classed as an STI.
How to tell them apart
You mostly can't, by symptoms alone. These conditions overlap heavily, and several are frequently silent, so a test settles which one (if any) you have. A clinician still reasons through a few discriminating features. Timing helps: chlamydia symptoms tend to surface within one to three weeks of an exposure, while a UTI or yeast infection can flare with no recent sexual contact. Urethral symptoms that keep returning after treatment raise suspicion for M. gen or unresolved NGU. And a urine test won't catch a throat or rectal infection. The table below lays out the contrasts a provider weighs.
Side-by-side comparison
| Cause | Typical symptoms | Tell-tale pattern | On a standard STI panel? |
|---|---|---|---|
| Chlamydia | Discharge, burning urination; often none | Appears 1–3 weeks after exposure; mostly silent | Yes (NAAT) |
| M. genitalium | Urethritis, cervicitis; often none | Persistent/recurrent after treatment for other causes | Often not — must be ordered |
| NGU | Mucoid/purulent discharge, dysuria, itching | Urethritis with chlamydia/gonorrhea negative | Diagnosed by exam + NAAT |
| UTI | Burning, urgency, frequency | Often no recent exposure | No (urine culture) |
| Yeast | Itching, thick discharge, irritation | Recurs with antibiotics, irritation | No |
How it's tested
Testing is usually a urine sample, a self-collected swab, or a quick exam depending on what's suspected. NGU specifically needs objective evidence of urethritis (white cells on a Gram stain or first-void urine) plus NAATs, not symptoms alone. It's free or low-cost at many health departments, Planned Parenthood, and Title X clinics, with results typically back in a few days. For the full how-to, including which sites to sample, see how to get tested.
What to do next
If your symptoms persist, the practical steps are: confirm you weren't tested too early by checking the recommended interval for your exposure on when to test after exposure; ask whether the right sites were sampled; and ask specifically about M. gen if urethral symptoms keep recurring, since it's often left off panels. Treatment depends on what's found, so don't self-medicate with leftover antibiotics. A wrong drug can mask the picture and drive resistance. Once a cause is identified, follow the standard course for that infection and have partners evaluated.
Red flags — when to get seen urgently
Don't wait for a repeat test if you have any of the following, which suggest the infection may have spread or there's another acute problem:
- Fever with lower abdominal or pelvic pain, which can signal pelvic inflammatory disease.
- Severe testicular pain or swelling, which can indicate epididymitis (inflammation of the tube behind the testicle that can affect fertility).
- Inability to urinate, blood in the urine, or pain so intense you can't function.
- Painful blisters or sores, which point toward herpes rather than a bacterial cause and need a different test.
- Pregnancy with any of the above, where untreated infection can affect the pregnancy.