Blood in the semen is typically a symptom of direct trauma, anticoagulant use or recent penile biopsies or tests. However it can also be a sign of a more serious health condition, like a sexually transmitted infection (STI), prostatitis or cancer.
Semen with blood is usually not a serious finding and tends to resolve on its own within a few days without any specific treatment.
However, if you notice blood in the semen frequently, or if it persists for over 3 days, you should see a urologist for further assessment and treatment as necessary.

What causes blood in the semen?
Blood can be noted in the semen for the following reasons:
1. Direct trauma
Direct trauma in the genital area (like a wound or a direct blow) is the most common cause of blood in the semen in men under the age of 40. Most men do not recall how it occurs, however it is important to assess the area for other signs of trauma, like other cuts, swelling, redness or bruising.
How to treat: Normally, in these cases, the blood resolves within 3 days and no specific treatment is necessary.
2. Anticoagulant use
Using certain medications, like anticoagulants such as warfarin or aspirin, can increase your risk for bleeding from small blood vessels. Bleeding can occur within the seminal tract, which can result in blood in the semen during ejaculation. This type of bleeding is rare, however.
How to treat: If bleeding lasts for more than 3 days, you should see a urologist. Be sure to report all medications you are currently taking to assess the need for an alternative or discontinuation.
3. Prostate biopsy
A prostate biopsy is an invasive test that uses a needle to remove tissue from the prostate. It often results in blood in the semen and urine, due to the trauma causes by the needle and tearing of small blood vessels.
How to treat: Bleeding is normal after this type of test and can last for up to 4 weeks. Nonetheless, you should see your doctor if you notice excessive bleeding or if you present with a fever over 100.4ºF (or 38 ºC).
4. Prostate or testicular inflammation
Inflammation in the male reproductive system, particularly in the prostate or testicles, are another common cause of blood in semen. It is important to monitor for other symptoms, like fever, genital pain or swelling in the testicles.
How to treat: If you suspect you have genital inflammation, you should see a urologist for further assessment and treatment as necessary, which may include antibiotics, anti-inflammatories or analgesics.
5. Benign prostatic hyperplasia
BPH is a common problem for men over 50 and is one of the main causes of blood in the semen in older men. Normally, this condition is associated with other symptoms like painful urination, difficulty urinating or urinary frequency.
How to treat: You are advised to complete prostate screen assessments after 50 years of age, which may include manual prostate inspection and bloodwork. This will allow for the identification of any problems that may require treatment.
6. STI
Although it is rare, the presence of blood in the semen can be a sign of an STI, like genital herpes, chlamydia or gonorrhea (especially if this symptom is noted following unprotected sex). Read more about the most common STIs and the symptoms associated with them.
How to treat: If you have had unprotected sex and notice symptoms like penile discharge, painful urination or fever, you should see a doctor for STI testing.
7. Cancer
Cancer is one of the most rare causes of blood in the semen. Nonetheless this disease should always be ruled out as a cause, especially if the patient is over 40, as bloody semen may be associated with some types of cancer, like prostate, bladder or testicular cancer.
Check out other potential symptoms of cancer that you should not ignore.
How to treat: You should see a doctor if you suspect cancer. Be sure to participate in regular cancer screening after 40 years of age to ensure any risks for cancer are identified early on.
8. Urethritis
Urethritis is characterized by inflammation of the urethra, usually caused by a urinary tract infection. It is associated with symptoms like pain when urinating, discomfort and genital burning, as well as discharge or semen with pus or blood.
Urethritis can be caused by bacteria transmitted during sex, such as Neisseria gonorrhoeae and Chlamydia trachomatis, or it can be consequence of using a urinary catheter.
How to treat: It is important to consult a urologist so that a diagnosis can be made and the most appropriate treatment can be started, which usually involves the use of antibiotics.
9. Urinary schistosomiasis
Urinary schistosomiasis is an infection caused by Schistosoma haematobium, which is a parasite that invades the urinary tract and leads to symptoms such as fever, chills, cough, muscle pain, blood in the urine and, in some cases, blood in the semen.
How to treat: it is recommended that a doctor be consulted to confirm the diagnosis and start treatment, which is normally done with the use of the antiparasitic praziquantel orally, in 2 to 3 doses on the same day, and may be recommended to repeat after 2 months.
10. Vasectomy
A vasectomy is a surgical procedure that is done to achieve permanent sterilization in men. It consists of cutting or blocking the vas deferens, which is the channel that carries sperm from the testicles to the penis. This interrupts sperm flow during ejaculation, and consequently preventing pregnancy.
However, a vasectomy can cause some complications, such as a hematoma in the scrotum or blood in the semen.
How to treat: The presence of blood in semen immediately following a vasectomy is considered normal. However, if it does not improve within a few days, you should follow-up with your urologist or family doctor.