- Sexual health & STIs
- Blood in Semen
Sexual Health · Symptom Guide
Blood in Semen
What causes blood in the semen (hematospermia), when a single episode is harmless, and when it needs a proper check. Reviewed by a licensed physician at a men's health clinic in Bangkok.
- Usually benign under 40
- Recurrent or over 40 needs a check
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Medically reviewed by Dr. Noppon Arunkajohnsak (Win)
Menscape Clinic
Last reviewed
11 July 2026
9 in 10
Cases are benign
under 40, single episode, no pain or other symptoms
40
Age to get checked
and any recurrent episode, at any age
26,000+
Men in one study
blood in the semen was reported by under 1%
1–2
Weeks it often lasts
a benign episode usually clears within a few weeks
Key takeaways
Blood in the semen (hematospermia) looks alarming, but in men under 40 with a single episode and no pain it is usually harmless and settles on its own.
The common causes are inflammation or infection of the prostate or seminal tract, a minor burst vessel, or a recent procedure such as a prostate biopsy or vasectomy.
Get checked if it keeps coming back, if you are over 40, or if it comes with fever, pain passing urine, blood in your urine, or unexplained weight loss.
A simple workup (urine test, STI panel, a PSA blood test when indicated, and an ultrasound if it persists) settles the question in most men.
See a doctor urgently, or call 1669, if you have heavy bleeding, severe pain, or cannot pass urine.
01
What blood in the semen is & why it happens
Hematospermia simply means blood in the ejaculate. It can look like a pink or red tinge, or, when the blood is older, a rusty brown colour. The seminal tract, the prostate, seminal vesicles and the tubes that carry semen, is packed with small, fragile blood vessels, so even a minor irritation can show up as colour in the semen.
The most common identifiable causes are inflammation and infection. Prostatitis, inflammation of the seminal vesicles, and sexually transmitted infections such as chlamydia are frequent culprits, especially in younger men. In a large share of cases, though, no specific cause is ever found, which doctors call idiopathic.
Mechanical and procedural causes are also common. Blood in the semen is expected after a prostate biopsy, and can follow a vasectomy, a urinary catheter, or a period of very frequent or very infrequent ejaculation. A tiny vessel can burst and then heal on its own.
Age is the single most useful guide. In men under 40 with one episode and no other symptoms, a serious cause is very rarely found. Over 40, or when the bleeding keeps returning, a doctor looks more carefully for a treatable cause. That is caution, not alarm.
Inflammation or infection
Prostatitis, seminal vesiculitis or an STI is the most common identifiable cause, particularly in younger men.
A minor burst vessel
The seminal tract is rich in tiny vessels; one can bleed after vigorous or prolonged activity, then heal on its own.
After a procedure
Blood in the semen is very common after a prostate biopsy, and can follow a vasectomy or catheter. It usually clears within weeks.⁶
Idiopathic or, rarely, structural
In many men no cause is found. Over 40 or when it recurs, a doctor checks for stones, cysts or, uncommonly, a prostate problem.⁴
02
When to get it checked in Thailand
A single episode under 40
One episode, no pain and no other symptoms, and you are under 40? It is very likely benign. A quick chat is still worth it, but urgent tests are rarely needed.
Recurrent, or over 40
Bleeding that returns over weeks, or any episode once you are over 40, should be assessed. This is when a doctor looks properly for a treatable cause.
With other symptoms
See a doctor promptly for fever, pain passing urine, blood in the urine, a lump, or unexplained weight loss. Call 1669 for heavy bleeding or if you cannot pass urine.
Reassurance grounded in data. In a screening study of more than 26,000 men, blood in the semen was reported by fewer than 1 in 100.² Published reviews find the great majority of episodes in younger men settle without any specific treatment.³
03
What the evidence says about cancer risk
Most men fear the worst when they see blood in the semen. The evidence is reassuring. Published reviews find that in men under 40 with a single episode, no pain and no other symptoms, a serious cause is very rarely found, and most episodes resolve on their own.³
The picture is more nuanced with age. A screening study of over 26,000 men found blood in the semen in fewer than 1 in 100, and because prostate problems become more common later in life, guidelines advise that men over 40, or those with repeated episodes, have a proper check rather than simply waiting.²
The honest summary: it is usually benign, but usually is not always. Recurrent bleeding, older age, or any warning sign is exactly why a doctor examines you and runs a few simple tests, so that the small number of serious cases are not missed.
9 in 10
Settle without treatment
younger men, single episode, no other symptoms
40
Age a workup is advised
and any recurrent episode, to find the cause
Figures are from published reviews and screening studies of hematospermia. Individual cases vary; only a doctor can assess yours.
04
How we find the cause & the tests we run
History & examination
The doctor asks about recent procedures, sexual history and symptoms, checks your blood pressure, and where appropriate performs a gentle prostate examination.
Urine test & STI panel
A urinalysis looks for infection and blood; an STI panel checks for chlamydia, gonorrhoea and others, which are common and treatable causes in younger men.
PSA, when indicated
For men over 40 or with risk factors, a PSA blood test and prostate assessment help rule out prostate disease. We explain what the number means before you test.
Ultrasound, if it persists
When bleeding keeps returning, a scrotal or transrectal ultrasound can show cysts, stones or dilated vessels. Further imaging is arranged only if something needs a closer look.
05
Related conditions & tests
Related condition
Prostatitis
Inflammation or infection of the prostate is a leading cause of blood in the semen, often alongside pelvic discomfort or urinary symptoms.
Get tested
STI screening
Chlamydia, gonorrhoea and other infections can cause bleeding and are easily treated. Discreet testing is a sensible first step for younger men.
Understand your result
PSA testing
The PSA blood test is one tool doctors use to assess the prostate, especially over 40. Knowing what it does and does not tell you helps you decide.
06
How a consultation works at Menscape
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Book a discreet consultation in Bangkok.
Chat with our team
Message us on WhatsApp or LINE and tell us what you have noticed. It is private, and there is no need to send photos.
See a doctor
A 15-minute consultation, in clinic at Phrom Phong or starting as a chat, where a licensed Thai physician reviews your history and symptoms.
Simple tests, if needed
If the doctor recommends it, we arrange a urine test, STI panel, PSA or ultrasound, and explain each result in plain language.
A clear plan
Most men are reassured and need nothing further. If a cause is found, such as an infection, it is treated and you are followed up.
No pressure, no judgment. Most men who come in for this are reassured quickly. If tests are needed, the doctor explains why before anything is done.
Medically reviewed by
Dr. Noppon Arunkajohnsak (Win)
Menscape Clinic, Bangkok
“Blood in the semen looks far more frightening than it usually is. In younger men a single episode almost always settles on its own. My job is to confirm that, and to make sure we do not miss the small number of cases that need treatment.”
- Reviewed
- 11 July 2026
- Next review
- January 2027
- Editorial standard
- Each guide is checked against the Thai FDA label and the primary literature, then reviewed by a licensed physician.
07
Frequently asked questions
Is blood in my semen a sign of cancer?
It is very rarely cancer, especially under 40. Reviews find most single episodes in younger men are benign and settle on their own. Over 40 or with repeated episodes, a doctor will check properly to rule out a prostate cause.
How long does blood in the semen last?
A benign episode often clears within a few days to 1–2 weeks. It can also come and go for a while. If it keeps returning, have it assessed.
I am under 40 and it happened once. Do I need tests?
Probably not urgent ones. A single episode with no pain and no other symptoms in a younger man is very likely harmless. A short chat with a doctor is still worthwhile for peace of mind.
What are the most common causes?
Inflammation or infection of the prostate or seminal tract, a minor burst vessel, or a recent procedure such as a prostate biopsy or vasectomy. In many men no specific cause is ever found.
Can an STI cause blood in the semen?
Yes. Chlamydia, gonorrhoea and other infections can cause bleeding and are common, treatable causes in younger men. A discreet STI panel is a sensible first check.
When should I go to hospital urgently?
Seek urgent care, or call 1669, if you have heavy bleeding, severe pain, a high fever, or you cannot pass urine. These are uncommon but need prompt attention.
Will a prostate biopsy or vasectomy cause this?
Yes, and it is expected. Blood in the semen is very common after a prostate biopsy and can follow a vasectomy or catheter. It usually clears within a few weeks.
Do I need to visit the clinic, or can I start on WhatsApp?
You can start as a WhatsApp or LINE chat. For most cases that is enough to guide the next step. Your doctor will ask you to come in to the clinic at Phrom Phong if a physical exam is needed.
08
References
1. Ahmad I, Krishna NS. Hemospermia. J Urol. 2007;177(5):1613-1618.
2. Han M, Brannigan RE, Antenor JA, Roehl KA, Catalona WJ. Association of hemospermia with prostate cancer. J Urol. 2004;172(6):2189-2192.
3. Kumar P, Kapoor S, Nargund V. Haematospermia: a systematic review. Ann R Coll Surg Engl. 2006;88(4):339-342.
4. Mathers MJ, Degener S, Sperling H, Roth S. Hematospermia: a symptom with many possible causes. Dtsch Arztebl Int. 2017;114(11):186-191.
5. British Association of Urological Surgeons (BAUS). Blood in the semen (haematospermia): patient information. Accessed July 2026.
6. Leocádio DE, Stein BS. Hematospermia: etiological and management considerations. Int Urol Nephrol. 2009;41(1):77-83.
This guide is educational information, not medical advice. Blood in the semen can have several causes; only a licensed physician can assess your situation and decide whether tests are needed.
This guide is part of the Menscape sexual-health library
Explore the condition hubBlood in your semen? Get a clear answer, not a scare.
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