Blood in Semen (Hematospermia): What It Means and When to Worry

Last updated: August 30, 2026

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Blood in semen — hematospermia in medical terms — is one of the most alarming things a man can notice, and one of the most frequent reasons men come to my andrology clinic. The blood is visible to the naked eye, which is exactly why it frightens both the patient and his partner. The reassuring news, which this article will explain, is that in most men it turns out to be harmless.

What hematospermia is

Hematospermia simply means blood present in seminal fluid. The colour ranges from light red through brown to dark clots, and in most cases it is painless. It is reported in roughly 1 in 5,000 urological patients. Importantly, no cause is ever identified in more than 70% of men — and that is not a failure of investigation, it is the usual outcome.

One distinction to make before anything else, because men frequently mix the two up when they describe it. This article is about blood in the semen. Blood in the urine is a different symptom with a different meaning, and it is one that always needs investigating properly rather than watching, whatever your age. If you have seen red in the toilet bowl or on the tissue when passing urine — as opposed to in the ejaculate — that is the thing to mention, and it changes what needs to be done.

The possible causes

1. Prolonged sexual abstinence — distension of the seminal vesicles can cause minor mucosal bleeding.
2. Trauma — a recent urological procedure (TRUS biopsy, cystoscopy), unusual sexual practices, or perineal injury.
3. Infection — of the prostate, bladder or urethra.
4. Organ-related causes — seminal vesicle obstruction or tumour, prostate polyps, calculi or tumour, testicular tumour, urethral pathology.
5. Systemic causes — hypertension, haemophilia and other coagulation disorders, liver cirrhosis.

Two of those deserve expanding, because they account for a good share of the cases I see and neither is obvious to the patient.

Blood-thinning medication. The list above mentions clotting disorders, but far more men are on a blood thinner than have an inherited bleeding condition. Warfarin, the newer oral anticoagulants, and even aspirin all make bleeding of any kind more visible, and a small bleed that would have gone unnoticed becomes obvious. If you take one of these, say so at your appointment — it genuinely changes the interpretation. Do not stop the medication yourself, though; the reason you are on it has not gone away, and stopping it unsupervised is a far bigger risk than the blood you have noticed.

After a prostate biopsy. If you have recently had a prostate biopsy, blood in the semen is expected rather than a complication, and it can persist for several weeks — sometimes a month or more — before it clears. It often looks worse than it is because older blood turns rusty brown. This is worth knowing in advance, because men who were not warned understandably assume something has gone wrong.

Why age 40 changes the approach

Managing hematospermia rests on a careful history, a proper physical examination, and investigation tailored to the individual rather than a fixed panel of tests. In practice, 40 is the age that divides the two approaches. A man under 40 with no underlying disease and an isolated episode can usually be reassured and observed, because the odds strongly favour a benign cause. A man over 40, or one with recurrent episodes or additional symptoms, warrants a fuller workup — PSA, urine analysis, semen culture, transrectal ultrasound, and MRI of the pelvis where indicated — to exclude a structural cause.

One small thing worth doing whatever your age, since hypertension appears on the list of causes and most men have no idea whether they have it: get your blood pressure checked. It costs nothing, it is often the only finding, and treating it is worthwhile for reasons far beyond this symptom.

When not to simply watch and wait

Most of this article is a case for calm. These are the exceptions, and they matter precisely because the rest of the page is so reassuring.

Go to an emergency department the same day — in Thailand you can call 1669 — if the blood comes with:

• Fever or shaking chills, particularly with pain low down between the legs, pain on passing urine, or feeling generally unwell — an infected prostate can make a man very ill quickly
• Inability to pass urine, or heavy bleeding with clots

And book an appointment rather than waiting it out if: the bleeding keeps happening over more than a few weeks; you have also seen blood when passing urine; you are over 40; you have noticed a lump or change in a testicle; or you have other urinary symptoms, weight loss or pelvic pain alongside it. None of these mean something is seriously wrong. They mean the question deserves an answer rather than a guess.

The psychological impact of hematospermia is often out of proportion to its medical seriousness, which is precisely why understanding the condition matters so much. If you have noticed blood in your semen, discuss it with a urologist or andrologist rather than worrying alone — in most cases the conversation ends in reassurance.

Frequently Asked Questions

Q1: Is bloody semen (hematospermia) dangerous?

In most cases, hematospermia is not dangerous and resolves on its own, particularly in men under 40 with no underlying medical conditions. Over 70% of cases have no identifiable cause. However, hematospermia that is persistent, recurrent, or occurs in men over 40 should be thoroughly evaluated by a urologist to rule out underlying conditions such as prostate disease, seminal vesicle pathology, or rarely, malignancy.

Q2: What causes blood in semen?

Common causes include prolonged sexual abstinence causing seminal vesicle distension, trauma from urological procedures or perineal injury, urogenital infections (prostate, bladder, or urethral), structural causes such as prostate polyps or seminal vesicle obstruction, and systemic conditions like hypertension, coagulation disorders, or liver cirrhosis. Blood-thinning medication, including warfarin, the newer oral anticoagulants and aspirin, is a common contributor in older men and should always be mentioned to your doctor. In over 70% of cases, no specific cause is identified.

Q3: I am on a blood thinner. Should I stop it?

No — not on your own account, and not because of this. Blood thinners make any bleeding more visible, so a small bleed that would otherwise have gone unnoticed becomes obvious, and that is worth telling your doctor because it changes how the finding is interpreted. But the condition the medication was prescribed for has not gone away, and stopping it unsupervised carries a far greater risk than blood in the semen does. Raise it at your appointment and let the decision be made properly.

Q4: I recently had a prostate biopsy. Is this normal?

Yes. Blood in the semen after a prostate biopsy is expected rather than a complication, and it commonly persists for several weeks, sometimes a month or more, before clearing. It often looks alarming because older blood turns rusty brown. What is not expected, and does need same-day attention, is fever, chills, difficulty passing urine, or feeling unwell after a biopsy — those suggest infection rather than ordinary post-procedure bleeding.

Q5: Does hematospermia mean I have prostate cancer?

Hematospermia alone is not a specific indicator of prostate cancer. While prostate pathology is among the possible causes, the vast majority of hematospermia cases in younger men are benign. However, men over 40 or those with additional symptoms such as urinary difficulties, pelvic pain, or elevated PSA should undergo a comprehensive urological evaluation including PSA testing and possible imaging to exclude serious underlying conditions.

Q6: Is blood in the semen the same as blood in the urine?

No, and the difference matters. Blood in the semen is usually benign, particularly in younger men. Blood in the urine is a separate symptom that always warrants proper investigation, whatever your age, because the list of causes is different and includes conditions that need finding early. Men often describe the two interchangeably, so be specific about which one you have seen — and if you have seen both, say so, because that combination changes the plan.

Q7: Is it harmful to my partner, and can we still have sex?

Blood in the semen is not itself contagious and poses no risk to a partner, and there is no medical need to stop having sex because of it. Two practical caveats. If an infection is the cause, that infection may be transmissible and should be treated before resuming, so it is worth having the cause established rather than assuming. And where a long gap between ejaculations was the cause, ejaculating more regularly may actually reduce recurrence. The bigger issue in practice is usually the alarm it causes a partner, which is best handled by explaining what it is rather than concealing it.

Q8: How is hematospermia investigated and managed?

The investigation approach depends on the patient’s age and associated symptoms. Men under 40 with no underlying disease and isolated hematospermia can often be reassured and monitored conservatively. Men over 40 or those with recurrent episodes require a thorough workup including PSA blood test, urine analysis, semen culture, transrectal ultrasound, and possibly MRI of the pelvis to identify any structural cause. Having your blood pressure checked is worthwhile at any age, since hypertension is one of the recognised causes and most men do not know whether they have it.

Q9: When does blood in semen need emergency care?

Go to an emergency department the same day, or call 1669 in Thailand, if the bleeding comes with fever or shaking chills — particularly alongside pain low down between the legs, pain on passing urine, or feeling generally unwell — because an infected prostate can make a man seriously ill quickly. The same applies if you cannot pass urine, or if there is heavy bleeding with clots. Blood in the semen on its own, with no other symptoms, is not an emergency.

Q10: Will hematospermia go away on its own?

In the majority of younger men with no underlying cause, hematospermia resolves spontaneously without treatment. Regular ejaculation may help reduce the recurrence associated with prolonged abstinence. However, if symptoms persist beyond a few weeks, recur frequently, or are accompanied by other urinary or systemic symptoms, a urological consultation is strongly recommended.

Q11: Can I discuss this by video consultation?

Yes, and it is a sensible first step for a symptom many men find awkward to raise. Bangkok Hospital Headquarters offers a Telemedicine service, arranged in advance by email to the Urology department at bhquro@bdms.co.th. A video consultation covers the history well — how long, how often, what colour, what medications you take, whether you have had a recent procedure — and that history is what decides whether any tests are needed at all. Examination and any tests are done in person afterwards. Samitivej Sriracha is in-person only, booked through the Urology department line 088-022-1445.

If you are experiencing bloody semen and are concerned about an underlying cause, Dr. Soarawee Weerasopone offers specialist andrology consultations at Bangkok Hospital Headquarters. Book a Consultation. Appointments at Samitivej Sriracha Hospital can be arranged by calling the Urology department on 088-022-1445. Questions about the cost of consultation, testing or treatment should go to the hospital directly — for Bangkok Hospital, by email to bhquro@bdms.co.th.

Reference

• Haematospermia: evaluation and management. PubMed 28382905

Disclaimer: This content is written and reviewed by Dr. Soarawee Weerasopone, a board-certified urologist at Bangkok Hospital Headquarters. It is intended for educational purposes only and does not constitute medical advice. Do not stop or change any prescribed medication, including blood thinners, on the basis of this article. No medical advice, diagnosis or prescription is provided through personal messaging channels or social media. Always consult a qualified healthcare professional before starting any medical treatment. In an emergency, attend the nearest emergency department — in Thailand the emergency number is 1669.