Low sperm count rarely causes obvious symptoms. Most men discover it only after trying to conceive for a year or more without success, then getting a semen analysis. A count below 16 million sperm per milliliter of semen is considered below the lower reference limit set by the World Health Organization, though that single number doesn’t determine fertility on its own.
The reality is that you can’t diagnose low sperm count by how you feel. But there are physical clues worth paying attention to, a clear testing process to follow, and some important context about what the results actually mean.
Most Men Have No Symptoms at All
Low sperm count, clinically called oligospermia, doesn’t usually announce itself. You won’t notice a difference in how your semen looks, how much you ejaculate, or how sex feels. The most common “symptom” is simply not getting your partner pregnant after months of unprotected sex.
That said, some men do experience signs that point to an underlying hormonal or structural problem that also happens to lower sperm production. These include decreased body or facial hair, erectile difficulty, noticeably low sex drive, or swelling, pain, or a lump on a testicle. None of these confirm low sperm count on their own, but if you’re experiencing them alongside trouble conceiving, they’re worth mentioning to a doctor because they help narrow down the cause.
What a Varicocele Feels Like
One of the most common treatable causes of low sperm count is a varicocele, an enlarged vein inside the scrotum. It usually develops on the left side. A large varicocele can feel like a soft mass above the testicle, sometimes described as a “bag of worms.” Smaller ones aren’t visible but can be felt during a physical exam.
Other signs include a dull ache that worsens throughout the day or after standing for long periods, and one testicle that’s noticeably smaller than the other. Lying down typically relieves the discomfort. Not every varicocele causes fertility problems, but they’re found in a significant portion of men being evaluated for infertility, and they can impair sperm production over time.
The Only Way to Know: A Semen Analysis
A laboratory semen analysis is the definitive test. You provide a sample by masturbation, typically at the clinic or at home with a short transport time, after abstaining from ejaculation for two to seven days. The WHO recommends that two-to-seven-day window; European guidelines suggest three to four days is the sweet spot. Abstaining too long or too briefly can skew results.
The lab evaluates your sample both under a microscope and by computer. A full analysis covers:
- Sperm concentration: how many sperm per milliliter
- Motility: what percentage of sperm are actively swimming
- Morphology: the size and shape of your sperm
- Vitality: what percentage of sperm are alive
- Volume: the total amount of ejaculate
- pH: the acidity level of the semen
Because sperm production fluctuates naturally, doctors typically want at least two analyses done weeks apart before drawing conclusions. A single abnormal result doesn’t necessarily mean there’s a lasting problem.
What About Home Sperm Tests?
Home testing kits are widely available, and some use your smartphone’s camera to analyze a sample. The most basic kits only tell you whether sperm are present at all. More advanced versions estimate concentration and motility.
The problem is that even the better kits capture only a fraction of what a lab analysis provides. They can’t assess morphology, vitality, or semen pH. And a “normal” home result doesn’t rule out male-factor infertility. You could have adequate concentration but poor motility or abnormal shape, issues that only a full lab workup reveals. Home tests can be a reasonable first step if you want a general sense of where things stand, but they don’t replace a clinical analysis when you’re seriously trying to evaluate fertility.
What the Numbers Mean
The WHO’s current reference limit puts normal sperm concentration at 16 million per milliliter or above. Below that is considered low. Total sperm count (concentration multiplied by the volume of the ejaculate) matters too.
It’s worth understanding, though, that recent WHO guidelines have moved away from treating these numbers as a hard line between “fertile” and “infertile.” The thresholds represent statistical reference ranges from studies of men who fathered children, not absolute cutoffs. Men with counts below 16 million do conceive naturally, and men above it sometimes don’t. The number gives your doctor a starting point for further investigation, not a verdict.
Blood Tests That Help Explain Why
If two semen analyses come back abnormal, the next step is usually a hormonal evaluation. A single blood draw can measure testosterone, FSH (the hormone that signals the testes to produce sperm), and LH (the hormone that triggers testosterone production). These are checked together because the pattern reveals where the problem originates.
Normal adult testosterone falls between 300 and 1,000 ng/dL. Low testosterone combined with low FSH and LH suggests a signaling problem from the brain (the pituitary gland or hypothalamus). Low testosterone with high FSH and LH means the testes themselves aren’t responding properly to normal hormonal signals. In some cases, doctors also check prolactin levels and iron stores, since a pituitary tumor or iron overload can quietly suppress the hormones that drive sperm production.
How Long Sperm Take to Regenerate
Sperm production isn’t instant. A single cycle of spermatogenesis, from stem cell to mature sperm, takes about 64 days (four 16-day stages). After that, sperm spend roughly two more weeks maturing in the epididymis before they’re ready for ejaculation. That means the sperm in today’s sample reflect conditions in your body about 10 to 11 weeks ago.
This timeline matters for two reasons. First, if you had a fever, illness, or period of heavy drinking two months ago, it could show up as a temporarily low count now. Second, if you make lifestyle changes to improve sperm production (losing weight, quitting smoking, reducing alcohol, managing heat exposure), you’ll need to wait at least two to three months before retesting to see if those changes made a difference. Testing too soon will only reflect the old cycle.
Physical Exam and What Your Doctor Checks
A fertility evaluation typically includes a physical exam of the scrotum. Your doctor will feel for varicoceles, check testicle size (smaller testes can indicate reduced sperm-producing tissue), and look for any lumps or abnormalities. They’ll also ask about your medical history: past surgeries, medications, infections, chemical exposures, and how long you’ve been trying to conceive.
Certain medications can suppress sperm production, including testosterone replacement therapy (which, counterintuitively, shuts down the body’s own sperm production), some antidepressants, and anabolic steroids. If you’re taking any of these, your doctor needs to know, because stopping or switching the medication may be all that’s required to restore normal counts over the following months.