Low testosterone symptoms in men

The symptoms most closely tied to low testosterone in men are sexual: a lower sex drive, fewer morning erections and erectile dysfunction. Tiredness, low mood, poor concentration, less muscle and more body fat are common too, but they have many other causes. That is why the two main guidelines, from the American Urological Association (AUA) and the Endocrine Society, never diagnose low testosterone from symptoms alone. They want symptoms or signs plus low results on two morning blood tests.

Here is what each guideline lists, which symptoms the research links most firmly to a low level, what else can pull your number down, and how the test works.

The symptoms guidelines list

The Endocrine Society guideline sorts symptoms and signs by how strongly they point to low testosterone:

The AUA’s list (Table 5 in its guideline) groups the same ground differently: physical (less energy and endurance, worse work or physical performance, fatigue, loss of body hair, less beard growth, less lean muscle, obesity), cognitive (depressive symptoms, poorer motivation, concentration and memory, irritability) and sexual (lower sex drive and weaker erections).

Notice how far apart the two ends of that table are. Very small testes or losing body hair point strongly to a hormone problem. Feeling tired or flat does not, on its own.

Which symptoms track the number most closely

The best data on this come from the European Male Ageing Study (Wu et al., 2010), which surveyed a random sample of 3,369 men aged 40 to 79 and measured their morning testosterone. Six symptoms were linked with the level: poor morning erections, low sexual desire, erectile dysfunction, being unable to do vigorous activity, depression and fatigue. But only the three sexual symptoms rose together as testosterone fell, and the more of them a man had, the lower his level tended to be.

The study defined late-onset hypogonadism (age-related low testosterone) as all three sexual symptoms together with a total testosterone below 320 ng/dL (11 nmol/L) and a low free testosterone. In plain terms: if your main complaints are tiredness or low mood without any change in sex drive or erections, low testosterone is a less likely explanation.

The AUA guideline makes the same point. It warns that mood changes, poor focus, lost strength, more belly fat, erectile problems and lower sex drive can come from chronic stress, chronic fatigue or depression rather than low testosterone. It reviewed four observational studies in which men with low testosterone reported fatigue somewhat more often, and found that men with ED have lower testosterone on average, but by a gap too small (about 47 ng/dL) to tell the two groups apart.

Signs a clinician looks for

Symptoms are what you notice. Signs are what a clinician can measure or see. The AUA recommends a targeted exam covering:

• body shape, weight and waist size
• the amount and pattern of body hair
• breast tissue, for gynecomastia
• the size and feel of the testes, and any varicocele

It also recommends testing men who are obese (BMI 30 or more, or a waist over 40 inches), because the link is strong. In one study the AUA cites, nearly a third of overweight or obese men had a total testosterone below 300 ng/dL, against 6.4% of men of normal weight.

Some men should be tested even with no symptoms at all. The AUA lists unexplained anemia, bone density loss, diabetes, chemotherapy, radiation to the testes, HIV, long-term opioid use, male infertility, pituitary problems and long-term steroid (corticosteroid) use.

How low testosterone is confirmed

Two morning tests

Testosterone peaks in the early morning and varies a lot from day to day. The AUA cites peaks around 3 to 8 a.m. in men who sleep at night, and levels 20% to 25% lower at 4 p.m. than at 8 a.m. in men aged 30 to 40. Its guideline says to diagnose low testosterone only after two total testosterone tests, taken on separate occasions, both early in the morning.

The Endocrine Society goes further: test after an overnight fast, because food and glucose can suppress testosterone, and repeat a low result. It notes that about 30% of men whose first test is in the low range have a normal level the second time.

The cut-offs

Both guidelines treat the number as half the diagnosis. The AUA states that a level below 300 ng/dL alone doesn’t define testosterone deficiency, and advises against testing men who have no symptoms, no signs and none of the conditions listed above. For what the numbers mean at different ages, see normal testosterone levels by age.

Follow-up tests

Once low testosterone is confirmed, the AUA recommends measuring luteinizing hormone (LH), the pituitary signal that tells the testes to make testosterone. The AUA explains that a high LH points to a problem in the testes, while a low or low-normal LH points to the pituitary or hypothalamus, and in that case prolactin should be checked too. Before any treatment, it recommends a hemoglobin and hematocrit test and, for men over 40, a PSA test.

What else lowers testosterone

The Endocrine Society lists several things that can pull testosterone down, some of them reversible:

• Weight and metabolic health: obesity, diabetes and sleep disorders.
• Medicines: opioids, glucocorticoids such as prednisone, and hormone treatments for prostate cancer. It notes that nearly all opioids, at doses equal to 30 mg of methadone, suppress testosterone production.
• Illness: acute illness and poor nutrition. The AUA cites a small study in which young men with respiratory infections saw their levels fall 10% on average, and up to 30% in some.
• Hormone causes: a high prolactin level and iron overload, among others.

The Endocrine Society says some low testosterone has functional causes that may be reversible by treating the underlying condition, and it recommends looking for the cause once low testosterone is confirmed. The AUA recommends counseling every man with low testosterone about lifestyle changes.

What treatment can and can’t fix

If low testosterone is confirmed, the AUA tells clinicians to set expectations by symptom. It says testosterone therapy may improve erectile function, low sex drive, anemia, bone density, lean body mass and depressive symptoms. It says the evidence is inconclusive on energy, fatigue, cognitive function, diabetes measures, cholesterol and quality of life.

That split mirrors the symptom research above: the sexual symptoms are the ones most tied to the level, and they are among the ones most likely to respond. If your main problem is fatigue, the AUA’s advice is to look for other causes too.

The AUA also recommends discussing stopping treatment after three to six months if testosterone reaches the normal range but your symptoms don’t improve.

Getting tested and treated online

Licensed telehealth clinics can order the morning blood tests, review them in a video visit and prescribe if you qualify. As of October 2026, Hone Health starts with a $65 biomarker test and physician video consult, Rex MD charges a $99 start fee covering labs at Labcorp or Quest and the first video visit, and TRT Nation charges $129 for blood work or accepts recent results you already have. See clinics with at-home tests and our step-by-step guide to getting TRT online.

Testosterone is a Schedule III controlled substance, as its labels state. Prescribing it without an in-person exam depends on a temporary DEA and HHS rule, 90 FR 61301, which runs through December 31, 2026 and requires a live audio-video visit with the prescriber.

If you want children soon, raise it before you start: testosterone lowers sperm production, and the AUA recommends against it for men currently trying to conceive. Options such as enclomiphene raise your own production instead; see enclomiphene vs TRT and TRT and fertility. Compare clinics on our testosterone hub or the testosterone provider rankings.

The bottom line

Low sex drive, fewer morning erections and erectile dysfunction are the symptoms most firmly linked with low testosterone. Fatigue, low mood and weight gain are common but have many causes. A diagnosis needs symptoms or signs plus two early-morning blood tests below the normal range, under 300 ng/dL by the AUA’s cut-off, and about 30% of first low results come back normal on a repeat. If yours are low, a licensed clinician should look for the cause before you start treatment.