Can A UTI Cause Blood In Urine?

Medically reviewed by Mr Maneesh Ghei, Consultant Urological Surgeon (GMC: 5208045). Last reviewed June 2026.

Can a UTI cause Blood in urine? Blood in our urine is known medically as haematuria, is one of the most alarming symptoms a person can notice and one of the most common reasons patients come to see me urgently. A UTI (urinary tract infection) is one of the leading causes, and it can produce visible bleeding. But haematuria has a long list of possible causes beyond infection, some of which require urgent investigation. This guide explains how UTIs cause blood in urine, when that bleeding is straightforwardly related to infection, and when it signals something else that needs ruling out.

How does a UTI cause blood in urine?

When bacteria, most commonly Escherichia coli, infect the urinary tract, they trigger an inflammatory response in the lining of the bladder (cystitis) or, in more severe infections, the kidneys (pyelonephritis). This inflammation irritates and damages the mucosal lining of the urinary tract, causing small blood vessels beneath the surface to rupture and leak blood into the urine.

The bleeding this produces can be:

• Microscopic haematuria: blood present only in quantities detectable by urine dipstick or laboratory analysis, not visible to the naked eye.
• Gross haematuria: visible blood that turns the urine pink, red, or brownish. This is what most patients notice and find alarming.

UTI-related haematuria is typically accompanied by the other hallmarks of infection: a burning sensation when urinating, increased frequency and urgency, cloudy or strong-smelling urine, and sometimes fever if the infection has spread to the kidneys. When all of these symptoms occur together, a UTI is the most likely explanation, but it still needs to be confirmed with a urine sample, not assumed.

Does blood in urine always mean a UTI?

No. While UTI is a common cause of haematuria, it is far from the only one, and some of the other causes are considerably more serious.

• Kidney stones: As a stone moves through the ureter, it irritates the lining and causes bleeding. This is usually accompanied by severe loin-to-groin pain (renal colic), though some kidney stones cause haematuria without significant pain.
• Bladder cancer: The most important diagnosis to exclude in any adult with haematuria. Bladder cancer classically causes painless, intermittent visible haematuria, blood in the urine without burning or frequency. Around 10,000 new bladder cancer cases are diagnosed in the UK each year, and it is more common in men and in smokers.
• Kidney cancer: Can also cause painless haematuria, sometimes as the only symptom in early disease.
• Prostate conditions in men: BPH, prostatitis, and prostate cancer can all cause blood in urine. Any man with haematuria requires prostate assessment as part of the workup.
• Trauma or injury to the urinary tract: Including after catheterisation or urological procedures.
• Certain medications: Blood thinners such as warfarin and apixaban can unmask haematuria from an underlying condition that was previously not causing visible bleeding.

The key clinical principle: haematuria is a symptom, not a diagnosis. Even when UTI seems the obvious explanation, confirm the urine has cleared after treatment and refer for further investigation if haematuria persists or recurs. It is also worth knowing what conditions can be mistaken for a UTI, as several serious diagnoses present with similar symptoms.

When is blood in urine a sign of something serious?

Painless visible haematuria, blood in urine without any pain, burning, or frequency, is a red flag. The absence of infection-type symptoms makes bladder cancer or kidney cancer more likely diagnoses to exclude. In the UK, NICE guidelines NG12 recommend a two-week wait urgent urology referral for any adult over 45 with unexplained visible haematuria, regardless of other symptoms.

Haematuria that does not clear after antibiotic treatment: if blood in urine persists once the infection is treated, the UTI was either not the sole cause or there is an underlying structural problem. This needs further investigation.

Recurrent haematuria: blood in urine on more than one occasion, even if each episode seems to resolve. Recurrent UTIs in men are themselves unusual and warrant urology review.

Haematuria with loin pain and fever: suggests pyelonephritis (kidney infection), which requires prompt antibiotic treatment and, if severe, hospital admission.

How is haematuria investigated?

The starting point is a midstream urine (MSU) sample sent for culture. This confirms whether bacteria are present and identifies the causative organism and its antibiotic sensitivities. A urine dipstick in clinic can detect blood rapidly, but the culture confirms infection.

If the blood persists after treatment, or if the initial presentation does not fit a straightforward UTI, further investigation typically includes:

• Flexible cystoscopy: A thin, flexible camera is passed into the bladder under local anaesthetic to look directly at the bladder lining. This is the gold standard for ruling out bladder cancer. Most patients tolerate it well and return to normal activities immediately after.
• CT urogram: An imaging scan of the kidneys, ureters, and bladder, with contrast, that can identify kidney tumours, stones, and structural abnormalities. This is the standard imaging investigation for unexplained haematuria.
• Urine cytology: Analysis of cells shed into the urine, looking for abnormal (potentially cancerous) cells. Used alongside cystoscopy, not as a replacement.
• PSA test for men: Prostate assessment is part of the haematuria workup in male patients.

In a man who smokes, is aged over 45, or whose haematuria is painless, this workup should happen promptly: within a two-week pathway on the NHS, or within days privately.

Can recurrent UTIs cause ongoing haematuria?

Recurrent UTIs are common in women, less so in men. Repeated episodes of cystitis repeatedly inflame the bladder lining, and haematuria can occur with each infection. Recurrent haematuria, even when each episode seems infection-related, always warrants a formal urology review.

There are two reasons for this. First, recurrent UTIs in men are unusual and usually indicate an underlying structural problem: bladder stones, prostate enlargement, a urethral stricture, or incomplete bladder emptying that creates a breeding ground for bacteria. Second, bladder cancer can present as recurrent apparent UTIs with haematuria. The cancer irritates the bladder lining in a way that mimics infection, and it is not uncommon for the real diagnosis to be delayed by months of antibiotic treatment for presumed UTI.

Frequently Asked Questions

Can a UTI cause blood in urine without other symptoms?

Occasionally, particularly in older patients who may not experience the typical burning and urgency associated with UTI. Blood in urine without other UTI symptoms should not be assumed to be infection-related. Painless haematuria in particular requires urgent investigation to rule out bladder or kidney cancer.

How long does blood in urine last with a UTI?

With prompt antibiotic treatment, blood in urine due to a UTI typically clears within two to three days as the infection resolves and inflammation subsides. If visible blood persists beyond 48 to 72 hours after starting antibiotics, or returns after a course of treatment, further investigation is needed.

Should I go to A&E for blood in urine?

Not always. If you have visible blood in urine with typical UTI symptoms (burning, frequency, urgency) and feel otherwise well, a same-day or next-day GP appointment is appropriate. A&E is the right destination if you have blood clots causing difficulty passing urine, cannot urinate at all, have severe pain with high fever and rigors, or feel systemically very unwell.

Can blood in urine be caused by a kidney infection?

Yes. Pyelonephritis (kidney infection) causes significant inflammation of the kidney tissue and can produce haematuria alongside the classic symptoms: high fever, shaking chills, severe loin or back pain, nausea, and vomiting. This is a more serious infection than cystitis and often requires hospital-level antibiotic treatment.

Is blood in urine more serious in men than women?

Haematuria in men is generally investigated more urgently than in women. UTIs are less common in men, so any UTI in a male patient warrants investigation for an underlying cause. Bladder cancer is around three times more common in men than women, and painless haematuria in a man over 45 requires a prompt urology review.

Can I have blood in urine without seeing it?

Yes. Microscopic haematuria, blood present in quantities too small to see, is detectable only on urine dipstick or laboratory analysis. It can be found incidentally on a urine test done for another reason. Microscopic haematuria requires assessment, though the urgency and investigation pathway differs from visible haematuria.

What antibiotic treats a UTI causing blood in urine?

The antibiotic is chosen based on the bacteria identified in the urine culture and local resistance patterns. Nitrofurantoin and trimethoprim are commonly used first-line for uncomplicated bladder infections in the UK, though local resistance rates influence prescribing. Your GP or urologist will select the most appropriate antibiotic once culture results are available. Do not request a specific antibiotic without a culture.

Can blood in urine go away on its own without treatment?

If the haematuria is truly due to a resolving UTI, it may settle as the infection clears. Blood in urine should never be left uninvestigated on the assumption it will resolve. Even if it does disappear, the underlying cause needs to be established, particularly if the episode was painless or you are over 45.

Sources

• NHS: Blood in urine (haematuria)
• NICE guideline NG12: Suspected cancer recognition and referral
• BAUS: Blood in urine patient information
• NHS: Urinary tract infections (UTIs)

This article is for information only and is not a substitute for personalised medical advice. If you have blood in your urine, seek prompt assessment from your GP or a consultant urologist.

About the Author

Mr Maneesh Ghei, Consultant Urological Surgeon (GMC: 5208045)

Mr Maneesh Ghei is a consultant urological surgeon with NHS and private practice across four London hospitals. He specialises in the diagnosis and management of prostate conditions including BPH, prostatitis and prostate cancer, as well as urinary symptoms, kidney stones and male sexual health. Mr Ghei sees new patients privately with same-week availability. No GP referral is required. Book a prostate screening consultation.