There is no reliable way to know if you have a low sperm count without a lab test. Semen looks and feels the same whether it contains 200 million sperm or nearly zero. The only definitive answer comes from a semen analysis, which measures sperm concentration, movement, and shape under a microscope. That said, certain physical signs, lifestyle factors, and medical history details can raise your odds of having a problem, and knowing what to look for can help you decide whether it’s time to get tested.
What Counts as “Low”
The World Health Organization sets the lower reference limit at 15 million sperm per milliliter of semen, or 39 million total sperm per ejaculate. Falling below either number is considered a low sperm count, clinically called oligospermia. Some men produce no sperm at all, a condition called azoospermia. It’s worth noting that these thresholds represent the lower end of normal fertility, not a hard cutoff. Men slightly above 15 million per milliliter can still have trouble conceiving, while some men below it father children without assistance.
Physical Signs That May Point to a Problem
Most men with low sperm count have no obvious symptoms. The condition is often discovered only after months of trying to conceive. However, an underlying hormonal or structural issue sometimes produces noticeable changes:
- Low sex drive or erectile difficulty. Both can signal low testosterone, which is directly involved in sperm production.
- Reduced facial or body hair. Thinning body hair or slow beard growth may indicate a hormone or chromosome condition affecting the testicles.
- Pain, swelling, or a lump near the testicle. A varicocele (enlarged veins in the scrotum) is one of the most common treatable causes of low sperm count. Varicoceles are found in about 10 to 15 percent of men generally, but in more than 40 percent of men evaluated for infertility. You might feel a soft, ropy swelling above or behind the testicle, often described as feeling like a “bag of worms.” Sometimes there’s a dull ache that worsens after standing or exercise.
- Breast tissue growth. Enlarged breast tissue in men can be a sign of elevated estrogen relative to testosterone.
None of these signs confirm low sperm count on their own, but if you notice one or more of them alongside difficulty conceiving, testing is a logical next step.
Lifestyle Factors That Lower Sperm Count
Your daily habits have a measurable effect on sperm production. If several of these apply to you, there’s a higher chance your count is below normal.
Body weight. Higher BMI correlates with lower sperm concentration and lower testosterone. Excess body fat converts testosterone into estrogen, disrupting the hormonal signals your testicles need to produce sperm. The extra insulation around the groin also raises scrotal temperature, which further impairs sperm production. Men with a BMI of 30 or above (the obesity threshold) face the greatest impact.
Smoking. Tobacco use is significantly associated with reduced sperm concentration, motility, and viability. The damage appears to come from increased oxidative stress, which harms sperm DNA.
Heavy drinking. Moderate alcohol intake doesn’t appear to cause major problems, but 10 to 14 or more drinks per week can decrease testosterone production, speed up testosterone clearance from your bloodstream, and raise estrogen levels. All of this suppresses sperm output.
Heat exposure. Sperm production requires a temperature slightly below core body temperature, which is why the testicles hang outside the body. Frequent hot tub use, prolonged laptop use on your lap, tight underwear, and long hours of sitting (especially in heated car seats) can all raise scrotal temperature enough to affect sperm quality over time.
Psychological stress. Chronic stress is linked to reduced sperm motility and concentration, likely through its effects on reproductive hormones like testosterone and cortisol.
Medications and Substances That Suppress Sperm
Several common medications can dramatically reduce sperm production, sometimes to zero.
Testosterone replacement therapy is the biggest culprit, and it catches many men off guard. When you take external testosterone, your body reads the high blood levels as a signal to stop producing its own. The hormonal signals that tell your testicles to make sperm get shut down. The result is often a very low sperm concentration or a complete absence of sperm. This is true for prescription testosterone in all forms: injections, gels, patches, and pellets.
Anabolic steroids work through the same mechanism. The degree of damage depends on the dose and duration of use, but long-term users frequently become temporarily or permanently infertile.
Chemotherapy drugs can significantly decrease or completely stop sperm production. Depending on the type and duration of treatment, production may return within two years, but for many men it never fully recovers.
Certain prostate medications (alpha-blockers like tamsulosin and silodosin) can sharply reduce ejaculate volume or prevent ejaculation entirely. SSRIs prescribed for depression and anxiety can also cause sexual dysfunction, particularly delayed ejaculation, which can complicate conception.
How a Semen Analysis Works
A semen analysis is the standard test for evaluating sperm count and quality. Your doctor orders it, and you provide a sample at a lab or fertility clinic. Here’s what to expect.
You’ll need to avoid all sexual activity that results in ejaculation for 2 to 7 days before the test. Both too short and too long an abstinence period can skew results, so staying within that window matters. On the day of the test, you’ll produce a sample by masturbating into a sterile container in a private room. You should urinate and wash your hands and penis beforehand, avoid lubricants or saliva (both can damage sperm), and collect the full ejaculate. If you miss any, let the lab know rather than trying to recover it.
The lab evaluates several measurements from your sample:
- Sperm concentration: the number of sperm per milliliter
- Total sperm count: the number of sperm in the entire sample
- Motility: the percentage of sperm swimming effectively in a straight line or large circles
- Morphology: the percentage of sperm with a normal shape
- Volume: the total amount of semen produced
- pH and liquefaction time: measures of semen chemistry and consistency
Because sperm count naturally fluctuates, a single abnormal result doesn’t seal the diagnosis. Most providers will repeat the test after a few weeks to confirm. Sperm take roughly 72 days to develop, so a temporary illness, high fever, or stressful period can temporarily lower your numbers.
At-Home Sperm Tests
Over-the-counter sperm test kits are available at pharmacies and online. These typically measure only sperm concentration and tell you whether you’re above or below a threshold (usually around 15 to 20 million per milliliter). In a clinical comparison of 40 samples, one popular kit matched laboratory results about 92.5 percent of the time. Two men with low counts were incorrectly told they were normal, and one man with a normal count was incorrectly flagged as low.
These kits can offer a rough first look, but they don’t measure motility, morphology, or volume, all of which affect fertility. A man with a normal sperm count but poor motility or abnormal shape could still have significant fertility problems. If you use an at-home kit and get a low result, or if your result is normal but you’re still not conceiving, a full laboratory semen analysis is the necessary next step.
When Testing Makes Sense
Fertility specialists recommend that both partners get evaluated at the same time when a couple is having difficulty conceiving. The general guideline is to seek evaluation after 12 months of regular, unprotected intercourse without pregnancy. If the female partner is over 35, that window shortens to 6 months. A male reproductive history and semen analysis should be part of any initial fertility workup.
You don’t need to be trying to conceive to get tested, though. If you have risk factors (a history of steroid use, undescended testicles, a known varicocele, or exposure to chemotherapy), or if you’re noticing symptoms like low libido, erectile problems, or testicular pain, a semen analysis can provide useful information about your reproductive health regardless of your plans for fatherhood.