Blood in semen (haematospermia): causes and when to worry

Published 22 October 2026

Seeing blood in your semen is unsettling, but it is usually caused by something minor and, in most men, it clears up on its own. It is most common in men under 40, where a single episode rarely points to anything serious; your age, how often it happens and what comes with it decide how far it needs investigating. This guide explains the causes, what the colour tells you, and when to get checked.

What is blood in semen?

Blood in semen, called haematospermia (or haemospermia), means blood has mixed with the fluid you ejaculate. The semen may look red, brownish-red or dark brown, sometimes with small clots, and it may or may not be painful.

Sperm are made in the testicles and travel up a tube called the vas deferens, but much of the fluid in semen is added further along, by the seminal vesicles (two small glands behind the bladder) and the prostate. Bleeding from small blood vessels anywhere along that route ends up in the ejaculate, which is why the possible causes are varied, and why most are minor.

Is blood in semen serious?

Usually not. It is rarely caused by anything serious, and it usually settles, either by itself or with anti-inflammatory treatment. Often no cause is found and the bleeding simply stops.

A 2017 review of the medical literature by Mathers and colleagues concluded that most men with haematospermia, particularly those under 40, have no serious underlying disease, while still advising a basic check after even a single episode.

Age and pattern change the picture. In men over 40, and where bleeding keeps returning, it is more often linked to a condition that needs treatment, sometimes prostate cancer. In one study of 300 men cited in that review, prostate cancer was the cause in 5.7%, and every one of those men was over 40 with either a raised PSA or an abnormal-feeling prostate. In a prostate cancer screening study of more than 26,000 men cited in the same review, 13.9% of those who reported blood in their semen, all of them over 40, were found to have prostate cancer. That is why a PSA test and a prostate examination are central to assessing an older man.

What does the colour of the blood mean?

Bright red usually means recent bleeding and brown or reddish-brown older bleeding, although fresh blood can also look brownish, and dark brown or black clots usually mean some time has passed since the bleed. Colour alone cannot tell you the cause; what matters more is whether the bleeding settles or keeps returning.

When the blood may not be in the semen

Blood in the urine can mix with semen, and blood from a partner can be mistaken for it. Doctors call this pseudo-haematospermia, and ruling it out comes first. If you also see blood when you pass urine, read our page on blood in urine, because that changes how quickly you should be seen.

What causes blood in semen?

Often no cause is found. When one is, it is usually low-grade infection or inflammation, or a recent procedure such as a prostate biopsy; both are usually temporary.

Infection and inflammation

Prostatitis, inflammation of the seminal vesicles, a urinary tract infection or infection of the testicles or epididymis can all cause bleeding. Prostatitis may also cause pain on passing urine or ejaculating; see our guide to chronic prostatitis. Tuberculosis and schistosomiasis are less common infective causes; schistosomiasis is mainly relevant if you have lived in or travelled to areas where it is common.

Sexually transmitted infections

Chlamydia, gonorrhoea, genital herpes and trichomoniasis are all listed among the causes, although the British Association of Urological Surgeons (BAUS) notes an STI is an unlikely explanation overall. If there is any chance of one, get tested: you do not usually need a GP referral for a sexual health clinic, and the NHS advises not having sex without a condom until you have been tested.

Recent procedures

A prostate biopsy, cystoscopy, TURP (an operation for an enlarged prostate), vasectomy or vasectomy reversal can all cause temporary bleeding, and brachytherapy (radiotherapy seeds placed in the prostate) has been linked to it. Biopsy and vasectomy are covered below.

Injury

Injury to the pelvis, the perineum (between the scrotum and the anus) or the genitals can damage small vessels, as can instruments or objects used during sexual activity.

High blood pressure

NI Direct lists severe high blood pressure among the less common causes, which is one reason your blood pressure is checked. The 2017 review notes the link is not proven beyond doubt.

Blood thinners and bleeding disorders

Anticoagulant and anti-platelet medicines, clotting disorders, sickle cell disease and severe liver disease can all play a part. A blood thinner can make bleeding more likely, so it is still worth finding the source.

Cysts, stones and other changes

Cysts or stones in the seminal vesicles or prostate, polyps and small dilated blood vessels can bleed. They show up on imaging, which is why scans are used when bleeding persists.

Cancer

Prostate, testicular and bladder cancer are rare causes. A lump or swelling in a testicle alongside blood in the semen should be checked promptly; see testicular pain if it is also sore.

Is blood in semen normal after a prostate biopsy?

Yes. The biopsy takes small samples of tissue from the prostate, and some bleeding into the semen afterwards is expected. In two large studies quoted in the 2017 review, more than 80% of men reported blood in their semen lasting up to four weeks. Prostate Cancer UK says it may be noticed for a couple of months, may look red or dark brown, and should get better by itself.

Bleeding that lasts does not mean the biopsy has found something: the same review found no demonstrable association between how long it lasted and the biopsy result.

Prostate Cancer UK advises seeing a doctor straight away if it takes longer to clear or gets worse. Get urgent help for:

• a high temperature, shivering or feeling very unwell, which can be a sign of sepsis and needs A&E straight away
• being unable to pass urine, or heavy bleeding or many clots in your urine or from your back passage: contact the hospital team who did your biopsy straight away, or go to your nearest A&E

Is blood in semen normal after a vasectomy?

Yes, a little blood the first few times you ejaculate is a recognised, short-lived effect: BAUS gives the chance of this as between 1 in 2 and 1 in 10 men.

BAUS advises contacting your surgical team if bruising, swelling or pain gets progressively worse day by day. Infection of the testicle and epididymis (epididymo-orchitis) is a recognised complication, so a painful, swollen testicle with a high temperature should be seen the same day: contact your surgical team, or call NHS 111 out of hours. Bleeding that continues well beyond the first few ejaculations, or returns weeks later, should be checked like any other episode.

When should you see a doctor about blood in semen?

NHS advice is to see a GP if you notice blood in your semen. It is not an emergency, but it should be checked, even after one episode. If you are paying for your own care, you can see a urologist directly.

Arrange an assessment soon if:

• you are over 40 (NI Direct and the 2017 review use this age; BAUS uses 45 for bleeding that keeps returning despite treatment)
• the bleeding keeps coming back, or has not cleared
• you have blood in your urine as well
• you have urinary symptoms, such as a weak stream or burning (see problems passing urine), or pain when you ejaculate
• you can feel a lump or swelling in a testicle
• you have a family history of prostate cancer, or a raised PSA
• you have lost weight without trying, or have any other unusual bleeding or bruising

BAUS notes that when it comes with an abnormal-feeling prostate or a raised PSA, the NHS route is normally an urgent, fast-track referral to urology.

Get same-day help (at A&E, or call 999 if you are very unwell) if you cannot pass urine and your bladder is full and painful, if you are passing heavy blood or clots in your urine, if you have a high temperature with shivering and feel very unwell, or if the bleeding followed a significant injury to the groin, testicles or pelvis. If you are unsure, call NHS 111.

What happens when you are assessed?

We match the tests to your age and pattern of bleeding rather than running everything as routine. The aim is to rule out the rare serious causes without over-testing a younger man with a single episode: basic checks for a man under 40 with one episode, and a fuller urological work-up for men over 40 or with repeated bleeding, a family history of prostate cancer, a raised PSA or blood in the urine.

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Not everyone needs every step. For blood in semen, the semen itself is not normally tested for infection, because harmless bacteria are often found in it. If you are having a PSA test, NHS advice is to avoid ejaculating for 48 hours beforehand; our guide to PSA levels by age explains how results are read.

How is blood in semen treated?

Treatment is aimed at the cause, and often none is needed, because it usually clears within a few days or weeks.

• Infection: antibiotics. If bleeding persists, a longer course of antibiotics or anti-inflammatory medicine is normally prescribed.
• High blood pressure or a bleeding tendency: treating the blood pressure, investigating clotting and, where relevant, reviewing anticoagulants with the prescriber.
• Cysts, stones or polyps: treated directly if they are the cause; cysts can sometimes be drained with a needle.
• A serious cause: managed on a specialist pathway; see prostate conditions.

Oestrogens and steroids have been used in the past, but the 2017 review found they lack a rationale and are not backed by studies. When every test is normal, the serious causes have been looked for and not found. Recurrence over a long period is common, so keep an eye on it and report further bleeding, especially if it becomes more frequent or painful.

Getting blood in semen checked in London

At The Andrology Centre your care is led by Mr Maj Shabbir or Ms Raveen Kaur Sandher, Consultant Urological Surgeons, or Ms Elsie Mensah, Urology Specialist, all of whom practise at Guy’s & St Thomas’, named by Newsweek in 2025 as the number one urology service in Europe. We consult at HCA at The Shard, HCA at Canary Wharf and HCA at Guy’s Hospital; read more about our consultants.

It helps to tell us how many episodes you have had, the colour, any recent procedure such as a biopsy or vasectomy, and any blood thinner you take. Self-funding patients need no GP referral; insured patients usually need one plus insurer pre-authorisation. Fees are on our fees and insurance page. Call +44 7889 318584 (Monday to Friday, 8am to 4pm), email contact@theandrologycentre.co.uk or use our contact page.

Frequently asked questions

References and further reading