Doctors call blood in the semen “hematospermia.” Injuries, infections, prostate issues, and several other factors and conditions can cause blood to appear in the semen.

Although it may be alarming, blood in the semen is not usually life threatening and does not necessarily mean that something is seriously wrong. In fact, in many cases, there is no clear cause at all.

Keep reading to learn more about the causes and symptoms of blood in the semen, as well as how to treat the issue.

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Blood in the semen may be a sign of a ruptured blood vessel.

When there is blood in the semen, the blood usually comes from either the prostate or the seminal vesicles, which make the majority of the semen.

In at least 70% of cases, however, a doctor is not able to identify the exact cause. If the bleeding happens only once, the likelihood of there being a serious underlying problem is very low.

The most common reasons for this type of bleeding include:

Ruptured blood vessel

A blood vessel in the prostate or seminal vesicles can rupture during sex or ejaculation. This is similar to when the nose bleeds following a sneeze. This may be more likely if the person is taking blood-thinning medications.

There may be a sudden gush of blood or bleeding that lasts for several minutes and then stops.

Some symptoms of a ruptured blood vessel include:

  • blood in the ejaculate
  • red bleeding
  • bleeding that appears suddenly then goes away

A ruptured blood vessel is not usually a serious health concern. Sometimes, however, an obstruction such as a cyst can put pressure on the blood vessels, causing them to rupture.

Having sex after long periods without it

Long periods of abstinence from sexual intercourse may cause blood to appear in the semen.

When this happens, a person may also notice:

  • bleeding during or after sex
  • blood in the ejaculate
  • a single episode of bleeding
  • light bleeding for a day or two

Infection

In males under 40, an infection or related inflammation is the most common reason for blood to appear in the semen.

In many cases, the infection occurs in the urinary tract, but it can also affect other areas, such as the prostate. This can develop due to typical urinary tract infections (UTIs) and sexually transmitted infections (STIs).

People with an infection may notice other symptoms, including:

  • pain or pressure when urinating
  • painful sex or ejaculation
  • swelling in the genital area
  • a fever, or generally feeling sick
  • frequent urination or difficulty emptying the bladder

Injury

Sustaining an injury to the urinary tract or genitals may cause blood to appear in the semen.

Sometimes, a minor injury — such as from vigorous sex — ruptures a blood vessel in the prostate or seminal vesicles. When this happens, a person may notice a sudden gush of blood that eventually goes away on its own.

More serious injuries can cause swelling, chronic bleeding, and serious damage to the genitals. When this happens, a person may notice bloody semen that either lasts for a long time or comes and goes following an impact to the genitals, genital surgery, or a fall.

Prostate issues

Problems with the prostate may give rise to bloody semen. One of the most common issues is prostatitis.

A 2015 study of 37 males with bloody semen found that two-thirds had some form of prostatitis.

Prostatitis can be a chronic issue due to inflammation or a sudden problem due to an infection. In either case, the person may notice symptoms other than hematospermia, including:

  • blood in the urine
  • painful urination
  • painful sex
  • a feeling of fullness or swelling in the rectum or genital area

Inflammation

Inflammation refers to swelling and irritation. Sometimes, this can occur alongside an infection, but it can also appear on its own.

Prostatitis is one form of inflammation, but irritation elsewhere in the genitals or urinary tract may also cause blood to appear in the semen.

Inflammation in the epididymis, which is the tube that holds the sperm, may also cause blood to appear in the semen.

A person may also experience other symptoms, such as:

  • prostatitis
  • pain when urinating
  • pain in the penis or groin
  • swelling and tenderness

A tumor

On rare occasions, a tumor may be the cause of blood in the semen. The most common tumor to cause this would be prostate cancer.

When this happens, a person may sometimes notice repeated bouts of hematospermia. They may also have other symptoms, such as painful urination or pain in the groin.

When blood in the semen occurs just once or happens following an injury or a lifestyle change, a tumor is not likely to be the cause.

Other factors

Though less common, there are some other issues that may cause blood in the semen. These include:

Anyone can develop blood in the semen, and doctors are often unable to identify a cause.

However, there are certain risk factors that increase the likelihood of experiencing hematospermia. These include:

  • having vigorous sex, especially after a long period of abstinence
  • being over the age of 40
  • having a history of prostate issues, including prostatitis
  • having a family history of prostate disease
  • having a urinary or genital infection

Evaluation will generally include a doctor taking a medical history, such as by asking about the person’s sexual history, conducting a physical examination, and running selected laboratory testing and imaging.

Tests may include:

  • a digital rectal and prostate examination
  • urinalysis and urine culture
  • prostate-specific antigen blood test, to evaluate for prostate cancer
  • semen analysis
  • direct urethral visualization with cystoscopy
  • prostate ultrasound imaging
  • prostate MRI imaging

In many cases, bloody semen does not require any treatment at all.

When the male is under the age of 40 and has few or no risk factors for cancer or other serious health issues, they may not need treatment for a single instance of hematospermia.

However, they may need treatment if there is an infection or a blockage. Some potential treatment options include:

  • antibiotics, for bacterial prostatitis and UTIs
  • anti-inflammatory medications, to treat inflammation
  • surgery, to remove blockages or treat problems with blood vessels
  • treatments for underlying conditions, such as STIs or chronic liver disease
  • medication, chemotherapy, or surgery, for tumors and other forms of cancer

Some doctors may recommend antibiotics even when they are unable to find an infection. In fact, one 2014 study found that a combination of antibiotics and an anti-inflammatory drug relieved symptoms in 96% of cases.

A single episode of blood in the semen is not an emergency. Nevertheless, it may be best to see a doctor to rule out more serious causes.

Doing so enables prompt treatment of any underlying issues and can offer significant reassurance if nothing is wrong.

It is also important to see a doctor for:

  • recurring blood in the semen
  • blood in the semen that gets worse with time
  • pelvic pain
  • urinary difficulties
  • possible infertility
  • swelling in the groin
  • signs of prostatitis, such as frequently using the bathroom or trouble urinating

Noticing blood in the semen can be alarming, but for most males who experience this, there is nothing to worry about.

Even when there is a more serious problem, seeking and receiving prompt treatment can prevent it from worsening. For this reason, anyone concerned about blood in the semen should speak to their doctor.