16 Causes of Blood in Your Urine

2. An Enlarged Prostate

An enlarged prostate, also called benign prostatic hyperplasia, is a common cause of blood in your urine. The prostate sits just below your bladder and surrounds the urethra, the tube that carries urine out of your body. As you age, this gland often increases in size.

When the prostate enlarges, it presses against the urethra and narrows the passage. This narrowing makes it harder for urine to flow freely. You may notice a weak stream, difficulty starting to urinate, or a lingering feeling that your bladder is not fully empty. Over time, this obstruction forces the bladder to work harder to push urine through the narrowed opening.

The added pressure and ongoing strain can irritate the bladder and nearby blood vessels. Small blood vessels may break, allowing blood to mix with your urine. You might see pink, red, or brown discoloration, and in some cases, small clots.

3. Kidney Disease

Kidney disease can cause blood in your urine when the tiny filters inside your kidneys become damaged. These filters, called glomeruli, clean your blood by removing waste and excess fluid. When they are injured or inflamed, they become more permeable than normal. This allows red blood cells to leak from the bloodstream into the urine.

In many cases, you may not see the blood yourself. The condition is often microscopic hematuria, which only appears during a urine test. Even without visible blood, the underlying filter damage can continue to affect how well your kidneys function. One common cause is inflammation of the kidney filters, known as glomerulonephritis.

Long-term conditions such as diabetes and high blood pressure can also gradually damage the delicate blood vessels in the kidneys. Over time, this ongoing injury weakens the filtering system and increases the likelihood that blood cells will pass into the urine.

4. A Urinary Tract Infection

A urinary tract infection, or UTI, occurs when bacteria enter the urinary system, which includes the kidneys, ureters, bladder, and urethra. Most UTIs affect the lower tract, especially the bladder (cystitis). When bacteria multiply, they irritate the lining of the urinary tract and trigger inflammation.

As the lining becomes swollen and irritated, small blood vessels can break and leak red blood cells into the urine. This may cause urine to appear pink, red, or brown. In some cases, the blood is microscopic and only found on laboratory testing.

Common symptoms include a burning sensation during urination, frequent urges to urinate, passing small amounts of urine, cloudy or strong-smelling urine, and lower abdominal discomfort. If the infection spreads to the kidneys, symptoms may include fever, back or side pain, nausea, or chills.

A urine sample is typically tested to confirm the infection by checking for bacteria, white blood cells, and red blood cells. UTIs are usually treated with antibiotics. Drinking fluids and emptying the bladder regularly may help flush bacteria from the urinary tract.

5. Bladder Stones

Bladder stones are hard mineral deposits that form inside the bladder. They develop when urine remains in the bladder for too long and becomes concentrated. As water is reabsorbed, minerals crystallize and gradually stick together, forming stones.

Bladder stones often occur when the bladder does not empty completely. Leftover urine allows minerals such as calcium, uric acid, or magnesium to settle and harden. Incomplete emptying may result from an enlarged prostate, bladder outlet blockage, nerve-related bladder problems, long-term catheter use, or repeated urinary tract infections.

As a stone shifts or presses against the bladder wall, it can irritate the lining. This irritation may damage small blood vessels and cause blood to appear in the urine. The urine may look pink, red, or brown, or blood may only be detected on laboratory testing.

Other symptoms can include lower abdominal pain, painful urination, difficulty starting or stopping urine flow, frequent urination, or sudden interruption of the urine stream. Larger stones may block urine flow and lead to infection or urinary retention.

6. Injury to the Bladder

An injury to your bladder can cause blood to appear in your urine. The bladder sits within the pelvis, where surrounding bones provide some protection. Even so, a strong external force can damage the bladder wall. Blunt trauma is a common cause of injury. This may occur during a car crash, a fall, or a direct blow to the lower abdomen.

If your bladder is full at the time of impact, the stretched wall is more vulnerable to tearing. A pelvic fracture can also injure the bladder, as broken bone fragments may puncture or press into the bladder tissue. Penetrating trauma, such as a stab or gunshot wound, can directly cut through the bladder wall.

Surgical procedures in the pelvic area may also lead to accidental injury. In some cases, medical instruments inserted through the urethra can cause damage if complications arise. When the bladder wall is torn or bruised, blood vessels within the tissue can rupture. Blood then mixes with urine and may appear visibly red or pink.

7. Injury to the Kidneys

A kidney injury can cause blood to appear in the urine. The kidneys filter waste and extra fluid from the blood through tiny blood vessels called glomeruli. When kidney tissue is bruised or torn, these vessels can break and leak blood into the urine.

Kidney injuries usually happen from a strong blow to the lower back or side, where the kidneys sit under the ribs. This can occur in car accidents, falls, contact sports, or physical fights. Stab wounds can also damage the kidneys. In some cases, medical procedures involving the urinary tract can cause temporary bleeding.

After an injury, urine may look pink, red, or brown as blood mixes with it. Some bleeding is visible to the eye, while other cases are detected only through laboratory testing. Additional symptoms may include flank pain, bruising over the lower back, abdominal swelling, dizziness, or signs of internal bleeding in severe cases.

8. Sickle Cell Disease

Sickle cell disease is an inherited blood disorder that changes the shape of your red blood cells. Instead of being soft and round, the cells become stiff and curved. These misshaped cells do not move easily through small blood vessels and can slow or block blood flow.

When this blockage occurs in the tiny blood vessels of the kidneys, it reduces oxygen delivery to kidney tissue. Repeated episodes of reduced blood flow can damage delicate structures inside the kidneys, including the small filtering units and surrounding vessels. As these tissues become injured, fragile blood vessels may leak red blood cells into the urine.

This leads to hematuria, which can appear during a pain crisis or even when you otherwise feel well. Over time, repeated sickling and vessel blockage can contribute to chronic kidney damage. As kidney function declines, the risk of blood appearing in the urine may increase.

9. Heavy Exercise

Heavy exercise can cause blood to appear in your urine, a condition often called exercise-induced hematuria. You may notice pink, red, or brown discoloration after intense physical activity, especially following long-distance running or very demanding workouts. During prolonged or high-impact exercise, repeated jarring motions, such as running on hard surfaces, can irritate the bladder lining.

This irritation may damage small blood vessels, allowing red blood cells to leak into the urine. Extreme physical exertion can lead to the breakdown of red blood cells, potentially causing blood in the urine. In most cases, the bleeding is temporary.

Once you rest and allow your body to recover, your urine typically returns to its normal color within a day or two. Many people do not feel pain, although mild lower abdominal soreness can occur. Wearing properly fitted athletic gear, staying hydrated, and gradually increasing exercise intensity may help reduce the risk of exercise-induced hematuria.

10. Alport Syndrome

Alport syndrome is a genetic condition that can cause blood in your urine. It develops because of inherited changes in genes responsible for producing a type of collagen, a protein that helps form the structure of the kidney’s filtering units. When this structural protein is abnormal, the tiny filters in your kidneys do not function as they should.

As these filters weaken, they become less effective at keeping blood cells and protein inside the bloodstream. Red blood cells can then leak into the urine, leading to hematuria. You may notice pink, red, or brown urine, but in many cases, the blood is microscopic and only found during routine testing. The bleeding often begins in childhood and can persist over time.

Alport syndrome can be passed from parents to children in different inheritance patterns. In many families, males experience more severe symptoms, while females may have milder signs, such as persistent blood in the urine.

11. Hemophilia

Hemophilia is a bleeding disorder that prevents blood from clotting properly. Clotting depends on proteins called clotting factors that work together to form a stable plug at the site of an injury. In hemophilia, the body does not produce enough of one of these key factors, so bleeding can last longer than normal, even after minor trauma.

There are two main types. Hemophilia A involves low levels of clotting factor VIII, while hemophilia B involves low levels of factor IX. Most cases are inherited and result from a gene change that affects the production or function of these proteins. Because clotting is impaired, bleeding can occur not only from visible injuries but also inside the body.

If bleeding develops in the urinary tract, including the kidneys or bladder, red blood cells can enter the urine. This may result in visible blood or may only be found through testing. Other signs may include easy bruising, frequent nosebleeds, bleeding gums, or joint swelling and pain caused by internal bleeding.

12. Trauma

Trauma can cause blood in your urine when a forceful injury damages part of your urinary tract, including the kidneys, bladder, or urethra. This type of injury may occur after a fall, car crash, sports collision, or a direct blow to the lower back or pelvis. When tissue in these areas is bruised, torn, or punctured, small and sometimes larger blood vessels can rupture.

The released blood then mixes with urine, causing it to appear pink, red, or brown. The bladder sits within the pelvic bones, which normally provide protection. However, a severe impact that fractures these bones can tear the bladder wall. If this happens, urine may leak into nearby tissues, leading to pain, swelling, and irritation.

The urethra, the tube that carries urine out of your body, can also be injured during pelvic trauma. This type of injury is more common in men because of the urethra’s length and position. Damage to this tube can result in bleeding, difficulty starting urination, loss of urine control, or blood visible at the tip of the penis.

13. Menstruation

Menstruation is a common reason blood may appear when you urinate. During your menstrual cycle, blood flows from the uterus through the cervix and out of the vagina. As urine leaves the urethra, menstrual blood can mix with it externally.

This may make it seem as though the blood is coming from the urinary tract, even when the kidneys and bladder are healthy. This is called contamination because the blood does not originate from the urinary system. It is more noticeable during heavier flow days. Even with tampons or menstrual cups, small leaks can happen.

Pads may also let menstrual blood mix with urine. Giving a urine sample when you are not on your period can help confirm if the blood is coming from the urinary tract. If bleeding occurs outside your normal cycle, continues after menstruation ends, or is accompanied by pelvic pain, fever, back pain, or burning during urination, another cause should be considered and medical evaluation is recommended.

14. Kidney Stones

Kidney stones form when minerals and salts in your urine become highly concentrated and begin to crystallize. Over time, these crystals stick together and grow into small stones or larger, hardened masses. Stones may remain in the kidney or travel into the ureter, the narrow tube that carries urine from the kidney to the bladder.

As a stone moves through the urinary tract, it can rub against and scrape the delicate lining. This friction irritates the tissue and may damage small blood vessels, allowing blood to leak into the urine. You may notice pink, red, or brown discoloration, although in some cases the blood is only detected on laboratory testing.

The movement of a stone can also trigger sudden muscle spasms in the ureter as it tries to push the stone forward. This leads to sharp, intense pain that often begins in the lower back or side and may spread to the lower abdomen or groin. You may experience nausea, vomiting, a frequent urge to urinate, or a burning sensation when passing urine.

15. Cancer

Cancer in the urinary tract can cause blood in the urine. It may affect the bladder, kidneys, ureters, or the prostate in men. Tumors can damage nearby tissues and small blood vessels, causing bleeding that mixes with urine. In some cases, especially with bladder cancer, painless blood in the urine may be the first sign.

Urine may appear pink, red, or cola-colored. Sometimes the bleeding is microscopic and found only during laboratory testing. Blood in the urine may come and go, which can delay attention even though the cause is serious. Other symptoms depend on the tumor’s location. Bladder cancer may cause pain during urination, urgency, or frequent urination.

Kidney cancer may cause persistent flank pain, unexplained weight loss, fatigue, or a mass felt in the side or abdomen. Prostate cancer may lead to weak urine flow, difficulty starting urination, or incomplete emptying. Risk factors include smoking, long-term chemical exposure, chronic bladder irritation, older age, and a family history of certain cancers.

16. It Isn’t Blood

Sometimes urine looks red or brown, but the color change is not caused by blood. Certain foods contain natural pigments that pass through the body and tint urine. Beets are a common example. Blackberries, rhubarb, and foods with artificial red or orange coloring can also temporarily change urine color.

Some medications may alter urine color as they are filtered by the kidneys. Laxatives, certain antibiotics, and some chemotherapy drugs can cause red, orange, or brown urine. Vitamin supplements, especially high doses of B vitamins, may also deepen urine color. Dehydration can concentrate these pigments and make the color appear darker.

Intense exercise can sometimes cause dark urine due to muscle breakdown, which releases pigments such as myoglobin. This is different from true bleeding but can still require medical attention if severe. Menstrual bleeding may mix with urine in the toilet and create confusion. Rectal bleeding can also be mistaken for blood in the urine.