When a man talks about having thick sperm, he likely is referring to his semen — in reality, it is the semen that appears thick rather than the sperm, as one cannot see sperm with the naked eye because it is microscopic. As for thick semen, this is often just a normal concurrence, as semen can vary in consistency. When it is a sign of an abnormality, however, dehydration, infections, and hormone imbalances are often the culprits. For example, if a man has lower-than-normal levels of testosterone, his semen may appear thicker than normal. In fact, some people may even describe the semen as lumpy.
The term "thick sperm" is something of a misnomer. Since sperm are microscopic, most men are really referring to their semen when they describe themselves as having thick sperm. It is important to note that there is some variation in what is considered normal when it comes to semen consistency. A man may have thin semen, semen that is of an egg-white consistency, or semen that seems a bit more gelatinous, and all of these are likely normal — some men just have thicker semen than others. If a man's semen truly seems abnormally thick, however, there are a few likely causes.
One of the possible causes of thicker-than-normal semen is dehydration. If a man hasn't been drinking enough fluids, his semen may become thicker than normal. This may even happen of he drinks a good deal of soda, coffee, or other dehydrating beverages rather than water. In such a case, the effects are usually only temporary.
It is also possible that an infection could cause thick semen, though this is a less common cause. A man may, for example, notice thick semen in conjunction with discolored ejaculatory fluids. In such a case, his semen may appear yellow or green, which might indicate an infection. If these symptoms are combined with a foul-smelling discharge from the penis, an infection is even more likely.
Interestingly, a hormonal imbalance is also among the things that may cause abnormally thick semen. For example, if a man has lower-than-normal levels of testosterone, he might notice this effect. The only way to be sure of the cause of a change in semen consistency, however, is to see a doctor. A doctor can check for a hormonal imbalance or infection and advise a man of whether his semen, and sperm, are normal or not.