Blood in the urine (hematuria) is rarely a classic STI symptom, but two bacterial infections — chlamydia and gonorrhea — can inflame the urethra enough to tint urine pink or red. More often, blood points to a urinary tract infection, kidney stones, or another urinary cause. Because these overlap and several STIs are silent, only a test settles which one it is.
often silent; discharge or burning if anything
discharge and burning; can also hit throat/rectum
| Item | Value |
|---|---|
| Chlamydia | curable — often silent; discharge or burning if anything |
| Gonorrhea | curable — discharge and burning; can also hit throat/rectum |
The short list of likely causes
When you see blood in your urine, the realistic suspects fall into two buckets. The first is an STI-driven urethritis — inflammation of the urethra (the tube urine passes through) — most commonly from chlamydia or gonorrhea, which irritate the lining enough that a little blood can appear alongside burning and discharge. The second, and statistically more common, is a non-STI urinary problem: a urinary tract infection, a kidney stone, or another issue affecting the bladder or kidneys.
These conditions share too many symptoms to separate by sight or feel alone, and several STIs cause no symptoms at all. Self-diagnosis fails here because overlapping signs turn any guess into a coin flip until a test gives you an answer CDC STI Treatment Guidelines, 2021.
Which STIs can cause blood in the urine?
Chlamydia
Chlamydia is caused by the bacterium Chlamydia trachomatis, and most US genital infections come from serovars D–K CDC Chlamydia Fact Sheet. When it infects the urethra, the resulting inflammation can produce burning on urination and, less often, blood-tinged urine. Why does blood show up? Inflamed urethral tissue is fragile, and the flow of urine across it can release small amounts.
Chlamydia is quiet. Roughly three quarters of infected women and half of infected men have no symptoms whatsoever. When symptoms do appear, they usually show up within one to three weeks after exposure. In women, the tell-tale pattern is abnormal vaginal discharge and burning on urination; if the infection climbs higher, it can bring lower abdominal or low-back pain, fever, pain during intercourse, and bleeding between periods that can be mistaken for urinary blood. Because reinfection is common after treatment, retesting matters; see our guide to chlamydia reinfection.
Gonorrhea
Gonorrhea is caused by Neisseria gonorrhoeae, a bacterium that can infect the genitals, rectum, and throat CDC About Gonorrhea. In the urethra it tends to provoke a more dramatic inflammation than chlamydia, so its urinary symptoms are often louder. In men, the classic picture is burning when urinating along with a white, yellow, or green penile discharge; less commonly, swollen or painful testicles signal that the infection has spread to the epididymis (the coiled tube behind the testicle that stores sperm), which can threaten fertility if untreated.
In women, gonorrhea is also frequently silent. When symptoms do occur, expect painful or burning urination, increased vaginal discharge, and bleeding between periods. That intermenstrual bleeding can be confused with blood in the urine, especially on toilet tissue or in the bowl. The discharge and burning of gonococcal urethritis are what most often accompany any visible blood, which is a secondary sign of an irritated urethra.
When it's NOT an STI
Most blood in the urine has nothing to do with an STI. The leading non-STI causes are:
- A urinary tract infection (UTI) — a bacterial infection of the bladder or urethra that inflames the lining and is one of the most common reasons urine turns pink or cloudy; it usually comes with frequent, urgent, burning urination.
- Kidney stones — hard mineral deposits that scrape the urinary tract as they move, producing visible blood plus intense, cramping flank or back pain that can come in waves.
- Other urinary causes — anything from vigorous exercise to bladder or kidney conditions can introduce blood, so any hematuria warrants a medical evaluation rather than a wait-and-see approach.
Blood in the urine always deserves to be checked out, regardless of how you feel otherwise. Even painless, one-time blood can point to something that needs attention.
How to tell them apart
You can't reliably tell these apart on your own. The clues clinicians weigh are still worth understanding. STI-driven urethritis usually travels with genital discharge and a recent sexual exposure, often one to three weeks earlier for chlamydia. A UTI leans toward frequency, urgency, and burning without discharge. Kidney stones announce themselves with severe, colicky flank pain. But these patterns blur constantly: a silent chlamydia infection produces no discharge to flag it, and a UTI can burn exactly like gonococcal urethritis. The discriminating features narrow the field, but only a test names the culprit.
Side-by-side comparison
| Cause | Typical extra symptoms | Often silent? | What confirms it |
|---|---|---|---|
| Chlamydia | Burning urination, abnormal discharge, pelvic/low-back pain, intermenstrual bleeding | Yes — most women, about half of men | NAAT (urine or swab) |
| Gonorrhea | Burning urination, white/yellow/green discharge, swollen testicles, intermenstrual bleeding | Often in women | NAAT (urine or swab) |
| UTI | Frequent, urgent, burning urination; cloudy urine; no genital discharge | No, usually symptomatic | Urine analysis & culture |
| Kidney stone | Severe cramping flank/back pain in waves, nausea | No | Imaging & urine testing |
How it's tested
For both chlamydia and gonorrhea, a nucleic acid amplification test (NAAT) is the recommended method. It detects bacterial genetic material from a urine sample or a self-collected swab, and for gonorrhea its sensitivity is usually above ninety percent with specificity around ninety-nine percent CDC Gonorrhea. In practice, testing is a urine cup, a quick swab, or a brief exam depending on what's suspected, and it's free or low-cost at health departments, Planned Parenthood, and Title X clinics, with results usually back in a few days. You can get tested without symptoms, and the details of the gonorrhea workup are covered in our gonorrhea test guide. If your exposure was recent, check when to test after exposure so you don't test too early to catch it.
What to do next
Don't try to wait out blood in your urine. Get a urine test that screens for both chlamydia and gonorrhea, and let the clinician rule out a UTI or stone with the same sample. Both bacterial STIs are curable with antibiotics once confirmed, usually a short course handled at the visit or follow-up. Skip self-treating with leftover pills; the wrong drug or dose can mask the problem and breed resistance. Tell recent partners so they can be tested too, which prevents the ping-pong reinfection so common with chlamydia.
Red flags — when to get seen urgently
Some blood in the urine needs same-day attention rather than a routine appointment. Seek prompt care if you have:
- Fever, chills, or severe lower-abdominal, flank, or back pain — possible signs the infection has spread to the kidneys or upper reproductive tract.
- Heavy or clotted blood, or blood that doesn't clear with the next urination.
- Swollen, painful testicles, which can indicate epididymitis (inflammation of the tube behind the testicle) that threatens fertility.
- Inability to urinate, severe pain, nausea, or vomiting, which may point to an obstructing kidney stone.
- Blood in urine during pregnancy, which warrants quick evaluation to protect both you and the pregnancy.