Peeing Blood—Why Does It Happen?

Most people pee between six and eight times a day, which means if something unusual is happening with your urine, you're probably going to notice straight away—especially if you're peeing blood.

Gross hematuria, the medical term for when you can see blood in your urine, might make your pee look pink, red, or brown, according to the NIH's National Institute of Diabetes and Digestive Kidney Diseases (NIDDK). (Microscopic hematuria, on the other hand, means the blood in your pee is only visible under a microscope.)

It's important to see a healthcare provider in order to determine the reason for the bleeding, no matter what other symptoms you're experiencing. Here are seven possible causes of blood in urine.

Urinary Tract Infection

"In women, the most common cause of gross hematuria typically is urinary tract infection," Norm Smith, MD, a urologist with NorthShore University HealthSystem near Chicago, told Health. UTIs occur when bacteria enter your body through the urethra and multiply in your bladder. Dr. Smith explained that the bacteria can cause irritation of the bladder, or cystitis, which can then lead to bleeding. Other symptoms of a UTI include a persistent urge to urinate, pain and burning with urination, and extremely strong-smelling urine.

Even if you're pretty sure you have a UTI, it's crucial you get checked out by a healthcare provider. "We see all the time a delay in diagnosis of bladder cancer in women who've been treated multiple times for what are thought to be urinary tract infections," Dr. Smith said.

Strenuous Exercise

In rare cases, intense exercising can result in blood in your urine, according to the NIDDK. Healthcare providers aren't totally sure why this happens, but they believe it could be linked to dehydration, trauma to the bladder, or the breakdown of red blood cells that occurs with aerobic exercise. Runners have been known to develop exercise-induced hematuria, but anyone can experience it after a really tough workout. Still, you shouldn't assume exercise is the cause and decide it's not serious. Always see a healthcare provider to be sure.

Kidney Infection

Kidney infection (or pyelonephritis) is a type of UTI that generally begins in your urethra or bladder and travels to one or both of your kidneys, per the NIDDK. Dr. Smith said the bacteria can irritate the lining of the kidneys, causing bleeding. Dr. Smith also added that a person with a kidney infection will likely have symptoms similar to those of a UTI—such as a persistent urge to urinate, pain and burning with urination, and strong-smelling urine—along with other symptoms like fever, chills, abdominal pain, nausea, and vomiting.

Bladder or Kidney Stone

The minerals in your urine can sometimes form crystals on the walls of your kidneys or bladder. Over time, those crystals can become small, hard stones. Some kidney stones are symptomless, but if one becomes large enough, it can create a blockage in your urinary tract and cause extreme pain. They can also irritate the lining of the urinary tract and, in turn, cause bleeding, Dr. Smith said.

According to the NIDDK, your healthcare provider might remove it or break it up into small pieces to get rid of the stone. Seek immediate medical attention if you experience pain so severe that you can't sit still or find a comfortable position as well as nausea and vomiting or fever and chills.

Inherited Disorders

Some genetic disorders can cause both visible and microscopic blood in your pee. One of those disorders is sickle cell disease—an inherited disorder that causes the body to create abnormally shaped red blood cells, the National Heart, Lung, and Blood Institute (NHLBI) stated. Other symptoms of sickle cell disease include episodes of pain, frequent infections, vision issues, and swelling of the hands and feet.

Alport syndrome, which affects the filtering membranes in the small blood vessels of the kidneys, is another inherited condition that can cause blood in urine. People with Alport syndrome experience progressive loss of kidney function, according to the NIH. Almost all affected individuals have blood in their urine, which is a sign of kidney malfunction. It can also cause symptoms like swelling, joint pain, hearing loss, and vision problems.

Certain Medications

Some drugs can make a person more likely to have blood in their urine, including blood thinners (medicines for blood clot prevention), pain relievers, and antibiotics, according to the NIDDK. Dr. Smith also said that some patients, especially those who have a condition that causes their bladder to bleed (like a UTI), might notice blood in their urine after taking a blood thinner such as aspirin. Dr. Smith added that even patients on blood thinners need to be evaluated by a professional to make sure the blood isn't caused by some other factor.

Some Cancers

Blood in your urine may most likely be due to a UTI, but it's important to be aware of the possibility that it could be cancer. Advanced kidney, bladder, or prostate cancer can cause blood in urine. The bleeding typically comes from the tumor itself, Dr. Smith said, though it can also be the result of irritation or inflammation. These cancers can also have symptoms like painful urination, fatigue, and pain in your back, side, or pelvis.

Overall, if you find that your urine looks out of the ordinary, always seek medical care to rule out any serious issues.