Free Guide to Understanding Blood in Urine

What Blood in Urine Means and Why It Occurs

Blood in urine, a condition doctors call hematuria, happens when red blood cells leak into your urinary system. This can occur anywhere from your kidneys (which filter waste from your blood) down through your bladder and urethra (the tube that carries urine out of your body). When you notice blood in your urine, it may appear bright red, dark red, or brown, depending on how much blood is present and how long it has been in your urine.

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Hematuria comes in two types. Gross hematuria means you can see the blood with your naked eye—your urine looks distinctly red, pink, or brown. Microscopic hematuria means there are red blood cells in your urine, but you cannot see them without a microscope. A doctor typically finds microscopic hematuria during routine urine tests. Both types deserve medical attention, though gross hematuria tends to be more alarming to people and more likely to prompt a doctor visit.

Many conditions can cause blood in urine. Urinary tract infections (UTIs) rank among the most common causes, affecting millions of Americans annually. According to the National Institute of Diabetes and Digestive and Kidney Diseases, about 150 million UTIs occur worldwide each year. Kidney stones represent another frequent cause—approximately 1 in 11 Americans will experience a kidney stone in their lifetime. Other causes include bladder or kidney infections, enlarged prostate glands (in men), menstruation (in women), strenuous exercise, certain medications like blood thinners, kidney disease, and various types of cancer affecting the urinary system.

Some people notice blood in their urine after intense physical activity, particularly distance running. This phenomenon, called exercise-induced hematuria, typically resolves on its own within 24 to 48 hours. In contrast, blood in urine that persists, returns repeatedly, or appears without an obvious cause requires medical evaluation to rule out serious underlying conditions.

Practical takeaway: Keep track of when you notice blood in your urine, what color it appears, whether you have other symptoms like pain or fever, and what you were doing when you noticed it. This information helps your doctor identify the underlying cause more accurately.

Common Causes You Should Know About

Urinary tract infections represent the leading cause of blood in urine, particularly in women. A UTI develops when bacteria enter the urethra and travel upward into the bladder or kidneys. Women experience UTIs more frequently than men because their urethra is shorter, giving bacteria a shorter distance to travel. Classic UTI symptoms include painful urination, frequent urination, urgency to urinate, cloudy or strong-smelling urine, and sometimes blood in the urine. Most UTIs respond well to antibiotic treatment prescribed by a doctor, and the blood in urine typically disappears once the infection clears.

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Kidney stones form when minerals and salts in urine crystallize and harden into solid deposits inside the kidneys. These stones can be as small as a grain of sand or as large as a golf ball. When a stone moves through your urinary tract, it can scratch or irritate the lining, causing blood to appear in your urine. People with kidney stones often experience severe flank pain (pain in the side between the ribs and hip), nausea, and the urgent need to urinate frequently. Approximately 10 to 15 percent of Americans will develop at least one kidney stone during their lifetime, with men affected twice as often as women.

Bladder and kidney infections, sometimes called pyelonephritis when the infection reaches the kidneys, can cause hematuria along with fever, chills, back pain, and general malaise. These infections are more serious than simple UTIs and require medical treatment. Glomerulonephritis, inflammation of the tiny filtering units in the kidneys, can also produce blood in urine. This condition may develop after a streptococcal infection or as part of an autoimmune disease.

In men, an enlarged prostate gland (benign prostatic hyperplasia) may cause blood in urine along with difficulty urinating and incomplete bladder emptying. Prostate cancer can also cause hematuria, which is why any unexplained blood in urine warrants professional medical evaluation. In women, blood in urine during or immediately after menstruation may simply reflect menstrual bleeding rather than urinary system bleeding, though persistent or unexplained hematuria still requires investigation.

Certain medications, particularly blood thinners like warfarin and aspirin taken in high doses, increase the risk of hematuria by making it easier for bleeding to occur. Similarly, people with bleeding disorders or taking anticoagulant medications should report any blood in urine to their doctor, as it may indicate that their medication dosage needs adjustment.

Practical takeaway: Note whether you have pain during urination, fever, back pain, or other symptoms alongside the blood in your urine. This helps narrow down possible causes and guides treatment decisions.

When to Seek Medical Attention

You should contact a healthcare provider about blood in your urine in most situations, though the timing depends on accompanying symptoms and how severe the hematuria appears. Seek medical attention within a few days if you notice gross hematuria (visible blood) that occurs without pain, as it could indicate various treatable conditions. If blood in your urine persists for more than a few days, recurs multiple times, or appears alongside other symptoms, schedule an appointment with your primary care doctor or a urologist (a doctor specializing in urinary system conditions).

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Seek medical attention more urgently if blood in your urine accompanies severe pain, particularly in your back, side, or abdomen. This combination may suggest kidney stones, which cause intense pain but are usually not life-threatening. However, the pain itself requires professional treatment for relief. Similarly, if you experience blood in your urine along with fever, chills, and burning during urination, these signs may indicate a kidney infection that needs prompt treatment with antibiotics.

Call emergency services or go to an emergency room if you have blood in your urine along with inability to urinate, severe abdominal or back pain that does not improve with over-the-counter pain medication, fainting, severe dizziness, or signs of shock (rapid heart rate, cold and clammy skin, confusion). These symptoms may indicate a serious condition requiring emergency medical care.

If you take blood-thinning medications and develop hematuria, contact your doctor rather than waiting for a routine appointment. Your medication dosage may need adjustment. Similarly, if you have a known bleeding disorder or take medications that affect blood clotting, report any blood in your urine to your healthcare provider, as it may signal a medication-related problem requiring intervention.

People with a family history of kidney disease, high blood pressure, or diabetes should take hematuria particularly seriously, as these populations face higher risks for serious urinary system conditions. Even microscopic hematuria discovered during routine testing warrants follow-up with a doctor to determine the cause and whether monitoring is needed.

Practical takeaway: Do not ignore blood in your urine hoping it will disappear on its own. While it often has a benign cause, only a medical professional can determine what is causing it and whether treatment is needed.

The Diagnostic Process Your Doctor Will Use

When you report blood in your urine to a healthcare provider, they begin by taking a detailed medical history. Your doctor will ask when you first noticed the blood, whether it is ongoing or intermittent, what color the urine appears, and whether you have other symptoms like pain, fever, or urinary urgency. They will also ask about medications you take, recent illnesses, family history of kidney disease, and recent injuries or strenuous activities. This conversation provides important clues about the underlying cause.

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Next, your doctor will perform a urinalysis—a laboratory test of your urine sample. This test can detect red blood cells, white blood cells (which suggest infection), bacteria, crystals (which may indicate stones), and protein. The urinalysis also measures the urine's pH level and specific gravity (concentration). If bacteria are present, your doctor may send the sample for culture, which identifies the specific bacteria and determines which antibiotics will work best against it. A urinalysis typically costs between $10 and $50 and produces results within one to two days.

If your doctor suspects a kidney stone, they may order imaging tests. An ultrasound uses