Semen Abnormalities

Semen abnormalities can range from discolored (non-white semen), abnormal semen odor, abnormal consistency (water, overly thick, lumpy), bubbly, or have abnormally low or high volumes.


Normally, semen is milky/off-white to slightly yellow (see below).  However, semen can become discolored, and the coloring can indicate different issues such as infections or bleeding in the reproductive tract.

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“Clear semen”, is usually not semen at all, rather it is often pre-ejaculate fluid or prostatic fluid – both of which mix with seminal vesicle fluid to make semen.  “Clear semen” is often noticed when only a portion of the semen ejaculated is clear while the other portion is milky white.  The most common culprit is typically pre-ejaculate fluid that is pressed out of the urethra with the first wave of ejaculation.  Pre-ejaculated is clear and slippery.  Some men release pre-ejaculate in the early stages of arousal long before ejaculation while some men might not release pre-ejaculate fluid until ejaculation begins.  In addition, some pre-ejaculate can remain in the urethra of the penis and that portion is pressed out by prostate fluid during ejaculation.  Prostatic fluid tends to be clear or very pale yellow.  The milky white color of semen is caused by the secretions of the seminal vesicles.  Since pre-ejaculate and prostate fluid are released in the first waves of ejaculation and seminal vesicle fluid is released last, the first portions of semen ejaculated can appear more clear then become more white as secretions from the seminal vesicles mix with the semen.  However, when “clear semen” is released without orgasm/ejaculation it is typically one of two things.  First, the release of pre-ejaculate fluid can occur during arousal or second, prostate fluid release without arousal.  Prostate fluid can sometimes be released in the absence of ejaculation.  This occurs most often during a bowel movement when hard stools presses against the prostate gland inside the body, forcing prostatic fluid into the urethra and out of the penis.  Sometimes a man will look in the toilet bowl and see a thick pale yellow fluid in the bowl or he may notice some thick fluid hanging from the tip penis that is thick like semen but fairly transparent.  Although this can occur naturally in many men, it is more common in men that either have prostatitis or prostatic congestion.   

“Light yellow semen” is usually no cause for concern.  In fact, the light yellow color is often caused by the small amount of urine left in the urethra.  This can occur especially in men who make little pre-ejaculate fluid to cleanse the urethra completely of urine.  Prostatic fluid is also slightly yellow so semen volumes that are slightly higher in prostate fluid for that particular ejaculation may be slightly more pale yellow than off-white.  In addition, certain yellow dies or sulfur in the diet (especially from garlic and onions) can be released in semen giving it a slightly yellow tinge.


“Yellow or greenish semen” typically indicated that there is an infection of the reproductive tract.  Just like nasal secretions turn dark yellow or greenish during a bacterial sinus infection, semen can do the same sort of thing with coloration when there is an infection in the reproductive glands.  Any dark yellow or greenish semen should be a sign to go see a healthcare provider.


“Pink, red, or brown semen” typically indicates blood in the semen usually caused by bleeding somewhere in the male reproductive tract.  In fact, semen with this color is a disorder called hematospermia.  More than one-fourth of cases are caused by prostatitis.  The inflammation of the prostate can be severe enough to cause some bleeding.  Bleeding in the urethra or anywhere along the reproductive tract can also cause some blood to mix with semen and this can be seen in men with sexually transmitted infections, or those involved in vigorous sexual activity/masturbation.  In some cases, blood comes from the seminal vesicles in men with seminal vesiculitis.  It isn’t uncommon for men with penile strangulation or that use penis rings during sexual activity to cause damage to the urethra thus causing hematospermia.  Most cases are benign (not dangerous), and resolve on their own.  However, if it doesn’t resolve within a couple of weeks, a healthcare provider should be seen.  In some rare cases, cancer in the reproductive tract can cause blood in the semen.  Darker brown semen often is a sign of older blood being ejaculated or it can also be caused by exposure to heavy metals.  Men with spinal cord injuries may also have dark brown to nearly black semen in some cases.





Semen typically smells like chlorine, bleach, or ammonia.  This has to do with the components of semen that often make it smell like you’ve just been to the swimming pool.  This smell can be more pronounced or stronger when mixed with sweat (so having a wet dream after a hot sweaty day may have a stronger smell than at other times).  In addition, in men who are not circumcised and have poor hygiene under the foreskin can cause smegma, sweat, and bacteria to mix with semen giving it a stronger smell.

Components from men’s diets can also cause some changes in semen smell.  Certain fruits and vegetables can make semen smell sweeter, while others like asparagus, alcohol, and caffeine can make semen have a more unpleasant smell. 

However, semen that has a strong fishy or rotten egg smell can indicate an infection in the reproductive tract and it should be checked out by a healthcare provider.  This may occur in prostatitis or in certain sexually transmitted infections like trichomoniasis or gonorrhea.  These can often be treated with antibiotics.  Since many men only ejaculate during intercourse, it’s important to determine if fishy or foul odors are coming from the semen or from the sexual partner (i.e. vaginal secretions).



Normally, semen is slightly thick upon ejaculation then liquefies shortly thereafter.  A few medical conditions can cause semen to become extremely thick and sticky, thin, or even lumpy and jelly like.

“Overly thick and/or sticky semen” is when semen is considerably thicker and even very sticky compared to normal semen.  This typically indicates some sort of genital tract infection that should be diagnosed and treated by a healthcare professional.  In some cases, these infections are sexually transmitted.  In other cases, thicker semen can be caused by thick prostatic fluid seen often in prostatitis and/or thick seminal vesicle fluid often seen in seminal vesiculitis.  One study found that more viscous (thick) semen is often associated with increased numbers of white blood cells in the semen, which is a sign of infection and inflammation in the reproductive glands that produce seminal fluids (seminal vesicles and prostate).[iii]


“Thin semen” usually doesn’t occur.  Most men that worry about this become concerned because when they pay attention to the consistency of their semen it is a minute or so after ejaculation (sometimes when examining their semen after removing a condom or waking up from a wet dream).  As stated previously, when semen is ejaculated it is slightly thick, but it quickly thins out after ejaculation.  As the different components of semen mix together, enzymes begin breaking down the thicker components to allow sperm to swim more freely so they can reach an egg and fertilize it.


“Lumpy or jelly-like” semen is typically caused by a hormone deficiency.  In this case, a medical professional should be seen to diagnose and treat the underlying condition causing this abnormality.




Gas bubbles ejaculated with semen is called pneumospermia and is rare.  There should be no air bubbles in semen as the reproductive tract is cut off from open areas that contain gas.  Bubbles in the semen can indicate inflammation in the seminal vesicles called seminal vesiculitis.  However, there are other causes, such as a fissure along the reproductive tract into the GI tract that allows gas bubbles to pass into the reproductive tract.  This is abnormal and seeing a healthcare provider is highly recommended.  


As stated previously, normal semen volume is between 2-5ml (½ to 1 teaspoonful).  It may be difficult for men to determine how much they ejaculate, and ejaculating simply to measure the amount of semen is NOT suggested.   Men who use condoms for birth control often have a rough idea of how much semen they ejaculate when removing a condom after sex.  In addition, men who have wet dreams typically can tell if there are issues if they wake with a very small wet dream stain (smaller than a coin) or if they wake up soaking through large portions of their underwear.   

Hypospermia is a condition defined as less than 2ml of semen per ejaculation.  Most causes of hypospermia revolve around similar issues that cause anejaculationPelvic tension and the use of penis rings may limit semen ejaculated out of the penis to a small amount, even though more semen was produced.  In this case, a large portion of that semen may have been “trapped” rather than ejaculated forward.  Likewise, retrograde ejaculation may be partial, with some semen moving backwards into the bladder and a smaller portion being ejaculated forward out of the penis at the same time.  Repeated ejaculations in a short period of time can also be a cause of hypospermia as the second ejaculation will produce less semen than the first ejaculation.[iv]  For a more complete overview on how the above causes of anejaculation can also cause hypospermia click HERE

Low testosterone can also cause hypospermia by decreasing the production of DHT.  In addition, as men age, they tend to produce less sexual fluid as testosterone levels decline, thus leading to smaller and smaller semen volumes over time.[v]  Medications that decrease testosterone, especially those that decrease DHT (5-alpha-reductase inhibitors) can decrease the volume of semen.  However, surgeries of the bladder or reproductive tract (especially removal of the prostate gland) or genetic abnormalities may also contribute to low semen volumes.  Men with certain forms of cystic fibrosis have a genetic mutation that can cause low semen volumes.    Typically any underlying cause of low semen volume can be treated, especially if low semen volumes are associated with infertility.  However, treatment is not administered simply to increase the volume of semen. 


Hyperspermia on the other hand is defined as semen volumes above 6ml per ejaculation.  Larger volumes of semen (larger than 6.3ml) affect about 1 in 20 men and may be seen more commonly in younger men rather than older men since testosterone levels are higher during adolescence.[vi]  However, much larger volumes are typically caused by sexual inactivity, prostatitis, and/or prostatic congestion. 


For men who are not sexually active and have infrequent wet dreams, ejaculation may only occur when the reproductive glands are especially full.  This may cause a man or young man to have especially heavy wet dreams which may be cause for concern.  However, if there are no signs of prostatitis or other abnormalities, it may just be nature’s way of eliminating a few weeks-worth of sexual fluid production. 

Prostatitis can also cause the prostate to produce a larger volume of prostatic fluid that when ejaculated, increases semen volumes considerably.  In some cases, men may ejaculate up to 15ml (a tablespoon of semen) during ejaculation.  Unverified sources have reported some men ejaculating as much as 50ml (nearly ¼ cup) of semen.[vii] 

Treatment of hyperspermia typically involves treating any underlying condition if it is present.  5-alpha reductase inhibitors can be used in adult men to decrease semen volume as DHT is a contributing factor to production of sexual fluids.  However, if an underlying cause can’t be found or the semen volume isn’t particularly bothersome, then typically no treatment is needed.     

[i] (11/11/19)

[ii] (last viewed 2/2/19)

[iii] Flint M, Relationship between semen viscosity and male genital tract infections, University of Stellenbosch, Department of Obstetrics and Gynecology, Faculty of Health Sciences, March 2012

[iv] (12/19/2016 - assessing hypospermia/definition)

[v] (12/19/2016 - sperm volumes decrease with age).

[vi] (12/19/2016 - 95th percentile of semen volume)

[vii] (up to 50ml - 12/19/2016)

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