Men’s hormones · Symptom guide

Medically reviewed by Melynda Fenn, FNP-C, Founder and Medical Director · Updated October 2026

Most men don’t come to our Peoria clinic saying, “I think my testosterone is low.” They tell us they just feel off, and it’s lasted long enough that it isn’t just a bad week. Here are the symptoms we hear about most, what else can cause them, and how to find out for sure.

The short answer: The most common symptoms of low testosterone in men are a lower sex drive, fewer morning erections or trouble with erections, fatigue that sleep doesn’t fix, irritability or low mood, losing muscle and strength, more belly fat, and trouble concentrating.³ Symptoms alone can’t diagnose it. Low testosterone is confirmed when you have symptoms and two early-morning blood tests show a total testosterone below 300 ng/dL.^{1, 2}

In this guide: Symptoms at a glance · The 7 signs · Low T or something else? · Who’s at risk · Getting tested · Treatment and safety · Testing in Peoria · FAQs · Sources

Low testosterone, also called low T or male hypogonadism, touches more than your sex life. The Endocrine Society’s guideline groups the signs like this:³

Sexual

Body

Mood and focus

Some signs point more strongly to low testosterone than others. Losing body hair or having very small testes is more telling. Fatigue, low mood and poor focus are common and have many causes, which is why a blood test matters.³

These are the symptoms men bring up most often at our clinic, and what each one tends to look like day to day.

A lower sex drive is one of the earliest and most common signs of low testosterone, and often the first one men notice. Testosterone is the main driver of sexual desire in men, so when levels fall, interest tends to fall with them.

Stress and fatigue affect libido too. The difference worth noting is how long it lasts. If desire has been low for more than a few weeks and nothing in your life explains it, that’s a reason to check your levels rather than wait it out.

What it looks like day to day:

Low testosterone can contribute to ED, and it’s worth testing for, but it’s rarely the only cause. Testosterone drives desire more than it drives erections. Erections depend mostly on healthy blood flow and nerves, so ED is more often linked to blood pressure, blood sugar, cholesterol, smoking, extra weight, poor sleep, stress, alcohol or a medication.

This one matters beyond the bedroom. ED can be an early marker of heart and blood vessel disease, sometimes years before other symptoms appear. That’s why a proper evaluation looks at more than hormones, and why “just get on testosterone” is the wrong answer to ED on its own.

What it looks like day to day:

Fatigue that doesn’t improve with rest is one of the most common complaints in men with low testosterone. Low levels can leave you drained even after a full night’s sleep.

Fatigue has many causes worth ruling out, including thyroid problems, anemia, sleep apnea, low vitamin D and depression. A good workup checks for those too, not just testosterone.

What it looks like day to day:

Low testosterone is linked with irritability, low mood and reduced motivation, and mood changes are one of the more common reasons men end up getting tested. A drop can show up emotionally before it shows up physically.

And no, it isn’t just the 115-degree August afternoon, though an Arizona summer doesn’t help anyone’s patience. If the shift has lasted months rather than weeks, it’s worth looking into. Low testosterone is one possible contributor among several, and a low mood deserves attention in its own right.

What it looks like day to day:

Testosterone helps build and repair muscle, so when levels fall, the same training produces less. This one tends to creep in over a year or two, which makes it easy to write off as getting older.

The tell is effort versus result. If your effort has stayed steady and your results have changed, something else is going on.

What it looks like day to day:

Low testosterone is linked with brain fog, trouble concentrating and memory complaints, and men with low levels often say they feel mentally dull.

Two honest caveats. Brain fog has many possible causes, including poor sleep, thyroid problems, low nutrient levels, medication side effects, depression and stress. And in a 2017 study, a year of testosterone treatment didn’t improve memory or thinking in older men with low testosterone and age-related memory complaints.⁵ Testing answers a question and may find a treatable cause, but testosterone alone isn’t a fix for focus.

What it looks like day to day:

Less semen and, less often, smaller testicles can go along with low testosterone, because the same hormone signals support sperm production.³

Worth knowing: noticeable shrinking is more often linked to taking testosterone or anabolic steroids from outside the body, which shut down your own production, than to age-related low testosterone. If you’re already using testosterone from any source, including online suppliers, tell your provider. Semen volume also varies with hydration, frequency and age, so one change isn’t a diagnosis.

Most of these symptoms aren’t specific to low testosterone. That’s why the American Urological Association says the diagnosis takes both symptoms and low blood levels.¹ These are the look-alikes worth ruling out:

Feeling down most days for two weeks or more? That deserves a conversation about depression, whatever your testosterone level. See our mental wellness care. If you’re having thoughts of suicide, call or text 988 any time.

Testosterone falls slowly with age, about 1% a year starting in your late 30s, but age is rarely the whole story.⁴ These raise the odds:^{3, 4}

Yes. Low T isn’t only an older man’s problem. In younger men it’s often tied to weight, sleep, opioid or steroid use, or a pituitary or testicular problem, so finding the cause matters as much as the number. Symptoms that show up well before midlife are worth checking, not accepting.

Low testosterone is diagnosed with blood work, not symptoms alone. Symptoms tell you whether to test. The lab tells you what’s actually happening.

1

Testosterone runs highest early in the day, so it’s drawn in the morning. The Endocrine Society recommends a fasting morning test.³

2

One low result isn’t enough. About 30% of men with a low first test are normal on the repeat, so a second morning test confirms it.^{1, 3}

3

Total testosterone is the starting point. Free testosterone, estradiol and LH help explain why it’s low, and a blood count, PSA, thyroid, A1c and cholesterol show what’s safe to treat.

4

The AUA uses a total testosterone below 300 ng/dL as a reasonable cutoff, but a number only means something next to how you feel.²

Reference ranges vary from lab to lab, so compare your result to the range printed on your report. Most clinicians treat a total testosterone below 300 ng/dL on two morning tests, together with symptoms, as low.^{1, 2} A level in range doesn’t rule out every problem, and a single low number doesn’t confirm one.

At-home finger-prick kits can give you a starting number, but they aren’t a diagnosis. If a kit shows a low level, confirm it with two early-morning blood draws before you consider treatment.

Treatment depends on how low your levels are, what’s causing it and what you want, including whether you plan to have children. These are the main paths:

If your levels are low, the first question is why. For men carrying extra weight, losing it usually raises testosterone on its own, and treating sleep apnea or changing a medication can help too.

When symptoms and two morning blood tests confirm low testosterone, TRT can improve sex drive, energy, mood and muscle. Most men use a weekly injection. Before starting, your provider checks your blood count, and once you’re on it, your levels are rechecked every 6 to 12 months.²

Testosterone from outside the body signals your testicles to make less sperm, and for some men sperm counts drop very low. The AUA says it shouldn’t be prescribed to men who are trying to conceive.² Tell your provider if children are in your plans; there are other options.

Testosterone therapy has been studied much more closely in the last few years, and the official guidance has changed with it.

In plain terms: the heart attack fear that shaped a decade of headlines wasn’t confirmed in a large trial, but testosterone still isn’t for everyone. Blood pressure, red blood cell count and PSA need regular checks, which is why anyone on TRT should be followed with labs rather than simply handed a prescription.

Your first visit is a conversation and a lab panel, not a sales pitch. We’ll tell you what the numbers show, including when they show your hormones are fine and the cause is somewhere else. That’s a useful answer too.

Your first visit runs about 30 to 40 minutes. We go over your symptoms, sleep, stress, medications, heart health and whether you plan to have kids.

We typically check total and free testosterone, estradiol, LH, a complete blood count, PSA, thyroid, A1c and cholesterol, and confirm a low result with a second morning test.

We walk through each result and what it means for how you feel. The plan may include testosterone therapy, weight and metabolic care, ED treatment, or nothing at all if your hormones are fine.

On testosterone, we recheck your levels, red blood cell count and PSA at about 6 to 12 weeks, then every 6 to 12 months. If your red blood cell count runs high, we can do a therapeutic blood draw here.

Morning hormone labs are drawn on-site in Suite 115.

We work alongside your primary care doctor and urologist, not instead of them.

Address: 7984 W Happy Valley Rd., Suite 115, Peoria, AZ 85383
Hours: Tue to Fri, 9:00 am to 5:00 pm · Sat, 10:00 am to 3:00 pm · Closed Sun and Mon
Your providers: Melynda Fenn, FNP-C, and Kenra Johnson, FNP-C
Referral: not needed. Book online, or call or text 602-540-3547.

Keep reading: Signs of a hormone imbalance in women and men · Men’s testosterone and ED care · Men’s mental health: signs men often miss

1. American Urological Association. Evaluation and management of testosterone deficiency (2018; reviewed and validity confirmed 2024)
2. American Urological Association. AUA releases new clinical guideline for diagnosis and treatment of testosterone deficiency (guideline statements), April 10, 2018
3. Bhasin S et al. Testosterone therapy in men with hypogonadism: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab 2018;103(5):1715-1744
4. Cleveland Clinic. Low testosterone (male hypogonadism): causes and risk factors
5. Resnick SM et al. Testosterone treatment and cognitive function in older men with low testosterone and age-associated memory impairment. JAMA 2017;317(7):717-727
6. Lincoff AM et al. Cardiovascular safety of testosterone-replacement therapy (TRAVERSE). N Engl J Med 2023;389(2):107-117
7. U.S. Food and Drug Administration. FDA issues class-wide labeling changes for testosterone products, February 28, 2025
8. U.S. Department of Health and Human Services. HHS announces requested updates to testosterone therapy product labels, June 18, 2026

What changed in this update (October 2026): we reorganized this guide around the full list of low testosterone symptoms, added the guideline definition of low T, a look-alike causes table, risk factors, at-home testing and fertility, and the June 2026 HHS and FDA labeling update, with links to every source.

Medical disclaimer: This article is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.