Yes, urinary tract infections can cause blood in your urine. This is one of the more alarming UTI symptoms, but it’s a well-known consequence of the infection irritating and damaging the bladder lining. The blood may be visible (turning urine pink, red, or cola-colored) or detectable only under a microscope during a routine urinalysis.
Why a UTI Causes Bleeding
The most common bacteria behind UTIs, called uropathogenic E. coli, attach to the outermost layer of cells lining your bladder. These bacteria latch onto the surface cells, invade them, and multiply inside until the cells rupture. As the cells burst open, they release bacteria back into the urine and expose the delicate tissue and small blood vessels underneath.
Your immune system responds by sending white blood cells to fight the infection, which creates inflammation throughout the bladder wall. That inflammation makes the tissue swollen and fragile, and tiny blood vessels near the surface can leak. The combination of direct cell damage from bacteria and the inflammatory immune response is what puts blood in your urine. In most UTI cases, the amount of blood is small enough that you won’t see it with the naked eye. Visible bleeding, sometimes called hemorrhagic cystitis, is less common.
Microscopic vs. Visible Blood
Blood in the urine falls into two categories. Microscopic hematuria means a lab finds three or more red blood cells per high-power field on a urine sample, but the urine looks normal to you. This is extremely common with UTIs and often discovered incidentally during testing. Gross hematuria means you can actually see the color change, ranging from faintly pink to deep red or brownish. Both types can occur with a UTI, though microscopic hematuria is far more frequent.
If your urine looks visibly bloody, that alone doesn’t tell you whether a UTI is the cause. Several other conditions produce visible blood, including kidney stones, vigorous exercise, enlarged prostate, and in some cases bladder or kidney cancer. That’s why testing matters, even if you suspect a straightforward infection.
How Kidney Infections Change the Picture
A lower UTI (bladder infection) can sometimes travel upward to the kidneys, causing a more serious infection called pyelonephritis. Kidney infections also cause blood in the urine, but they come with additional warning signs: fever, chills, pain in your lower back or side, nausea, and a general feeling of being suddenly and noticeably sick. A simple bladder infection rarely causes fever or back pain, so those symptoms suggest the infection has moved beyond the bladder. Kidney infections require more aggressive treatment and a longer course of antibiotics.
How Long Bleeding Lasts After Treatment
One of the most frustrating aspects of UTI-related bleeding is that it often lingers well after the infection itself clears. A 2025 study tracking hematuria resolution after UTI treatment found that only 38% of patients had a negative urine test at 30 days. Half still showed traces of blood at 60 days, and it took a full 180 days (six months) for 75% of patients to test completely clear.
This doesn’t mean the infection is still active. It means the bladder lining takes time to fully heal after being damaged. If your doctor wants to recheck your urine after treating a UTI, waiting at least 12 weeks gives the most reliable results. Testing too early, within the first few weeks, frequently shows residual blood that has nothing to do with an ongoing infection.
Other Causes of Blood in Urine
Not every case of bloody urine is a UTI. The National Institute of Diabetes and Digestive and Kidney Diseases lists several other common causes:
- Kidney stones can scratch the lining of the urinary tract as they move, causing bleeding with or without pain.
- Enlarged prostate (benign prostatic hyperplasia) frequently causes microscopic blood in older men.
- Intense exercise can temporarily produce blood in urine, particularly after long-distance running.
- Endometriosis may involve the bladder and cause cyclical bleeding tied to the menstrual cycle.
- Bladder or kidney cancer is a less common but more serious possibility, particularly in adults over 50 who see persistent visible blood without other UTI symptoms like burning or urgency.
If you have blood in your urine but no classic UTI symptoms (painful urination, frequency, urgency), or if the bleeding persists after your infection has been treated, those are reasons to get further evaluation. Persistent or unexplained hematuria sometimes prompts imaging or a closer look at the bladder to rule out structural problems or growths.
What to Watch For
A small amount of blood during an active UTI is common and typically resolves with treatment, even if it takes weeks to fully clear. But certain combinations of symptoms suggest something more urgent: a high fever paired with bloody urine, severe flank or back pain, an inability to urinate, or passing large clots. These patterns can point to a kidney infection, a stone blocking the urinary tract, or another condition that needs prompt attention.
If you’re seeing visible blood in your urine for the first time, getting a urinalysis and urine culture is the most straightforward next step. The test identifies whether bacteria are present and, if so, which antibiotic will work best. For people who’ve already been treated for a UTI and still notice blood weeks later, that lingering trace is often just the bladder finishing its healing process, not a sign that treatment failed.