Short answer: Low testosterone symptoms in men over 40 may include reduced sex drive, fewer spontaneous erections, erectile problems, low energy, loss of muscle mass, infertility, irritability, depressed mood, or difficulty concentrating. Because these signs are not specific, diagnosis requires compatible symptoms plus consistently low testosterone on at least two separate early-morning blood tests.
Noticing a change after 40 does not automatically mean you have low testosterone, or “low T.” Sleep problems, diabetes, obesity, medication effects, depression, thyroid disease, relationship stress, and cardiovascular conditions can produce similar concerns. A careful hormone evaluation and treatment discussion should identify the likely cause before any prescription is considered.
Key takeaways
- Symptoms and a low laboratory value are both required to diagnose testosterone deficiency.
- Sexual symptoms tend to be more suggestive than fatigue, weight gain, or poor concentration alone.
- Testosterone should usually be measured on two separate mornings because levels vary.
- Erectile dysfunction has many possible causes and is not proof of low testosterone.
- Testosterone therapy can suppress sperm production and requires ongoing monitoring.
What is low testosterone?
Male hypogonadism means the testes do not produce enough testosterone, the brain does not send the right signals to stimulate production, or both. Testosterone supports sexual function, sperm production, red blood cell production, muscle and bone health, and other body systems.
Testosterone often decreases gradually with age, but professional guidelines do not define normal aging alone as a disease. The Endocrine Society recommends diagnosing hypogonadism only when a man has relevant symptoms or signs and unequivocally, consistently low testosterone concentrations. Routine population screening of men without symptoms is not recommended.
Possible low testosterone symptoms in men over 40
Symptoms vary in their usefulness. A cluster of sexual and physical changes is generally more informative than one nonspecific complaint.
| Symptom or sign | How it may relate to testosterone | Common overlaps to consider |
|---|---|---|
| Reduced sexual desire | A common symptom of testosterone deficiency | Stress, depression, relationship factors, medications, sleep loss |
| Fewer spontaneous or morning erections | May occur with androgen deficiency | Vascular disease, diabetes, sleep disruption, medication effects |
| Difficulty getting or maintaining an erection | Low testosterone can contribute, especially with reduced desire | Blood-vessel, nerve, medication, thyroid, and psychological causes |
| Reduced muscle mass or strength | Can develop with prolonged deficiency | Inactivity, inadequate protein, illness, aging, medication effects |
| Low energy, poor concentration, or low mood | May be present but is nonspecific | Sleep apnea, anemia, thyroid disease, depression, chronic illness |
| Infertility, smaller testes, breast tenderness, or hot flashes | Can be important signs, particularly with marked deficiency | Other reproductive, medication-related, pituitary, or testicular causes |
Sexual and reproductive changes
Reduced libido, fewer spontaneous erections, and infertility are among the more recognizable features. Erectile dysfunction may coexist, but erections depend on blood flow, nerves, medications, emotional health, and relationship context as well as hormones. NIDDK lists diabetes, cardiovascular disease, obesity, chronic kidney disease, thyroid problems, medications, smoking, anxiety, and depression among possible contributors.
That distinction matters because treating testosterone will not correct every cause of erectile dysfunction. Persistent symptoms deserve a broader erectile dysfunction evaluation, especially when they may signal diabetes or vascular disease.
Body composition, energy, and mood
Some men notice less muscle mass, increased body fat, reduced exercise capacity, lower energy, irritability, depressed mood, or trouble concentrating. These changes can occur with testosterone deficiency, but they are also common with insufficient sleep, untreated sleep apnea, sedentary routines, major calorie restriction, alcohol use, mood disorders, and many medical conditions.
Severe or prolonged deficiency may contribute to reduced bone density, fewer red blood cells, decreased body hair, breast enlargement or tenderness, and smaller testes. Hot flashes are possible when testosterone is very low. These findings warrant medical evaluation rather than self-treatment.
Evaluate the pattern before treating the number
Live Well Wellness Center can review your symptoms, medications, sleep, health history, fertility goals, and appropriately timed testing before discussing options.
Book a ConsultationWhy testosterone can be low
Primary hypogonadism begins in the testes. Possible causes include injury, infection, certain genetic conditions, chemotherapy, or radiation. Secondary hypogonadism involves the hypothalamus or pituitary gland, which normally signal the testes. Pituitary disorders, high prolactin, some genetic conditions, and other medical problems can affect those signals.
Testosterone may also be reduced or temporarily suppressed with obesity, poorly controlled diabetes, severe illness, undernutrition, excessive training, untreated sleep disorders, or certain medications. Opioid pain medicines and glucocorticoids are important examples. Previous anabolic steroid or nonprescribed testosterone use can disrupt natural production after stopping.
Finding the cause changes the plan. Weight-related metabolic health, a medication effect, a pituitary problem, and primary testicular failure should not all be managed as though they are the same condition.
How low testosterone is diagnosed
Two separate early-morning blood tests
Testosterone changes through the day and can fluctuate between days. The American Urological Association and Endocrine Society recommend confirming a low result with a second early-morning measurement on another day. Testing during an acute illness can produce an artificially low value, so timing and clinical context matter.
The AUA uses total testosterone below 300 nanograms per deciliter (ng/dL) as a reasonable cutoff supporting diagnosis. This is not a stand-alone pass-or-fail number. Laboratories use different methods and reference ranges, and a diagnosis still requires relevant symptoms or signs. Free testosterone may be useful in selected situations, not as an automatic replacement for a properly measured total level.
Testing the cause, not just the level
When low testosterone is confirmed, additional evaluation may include luteinizing hormone and follicle-stimulating hormone to help distinguish a testicular cause from a pituitary or hypothalamic cause. Depending on the history and results, a clinician may consider prolactin, thyroid testing, blood counts, iron-related testing, metabolic screening, fertility testing, or pituitary imaging.
A physical examination and medication review are also important. Tell your clinician about supplements, bodybuilding products, prior hormone use, snoring or witnessed breathing pauses, testicular injuries, headaches, vision changes, and fertility plans.
When should a man over 40 seek an evaluation?
Arrange a visit when reduced desire, erectile changes, loss of spontaneous erections, infertility, persistent low energy, loss of strength, breast tenderness, or mood changes are new, sustained, or affecting quality of life. Evaluation is particularly important when multiple symptoms appear together or there are risk factors involving the testes, pituitary, diabetes, obesity, medication use, or prior cancer treatment.
Seek timely care for a new testicular lump, swelling, significant injury, severe headache with vision changes, or rapid unexplained physical changes. Chest pain, sudden shortness of breath, fainting, or stroke-like symptoms require emergency care, regardless of whether testosterone is involved.
What to know before considering testosterone therapy
Testosterone therapy may help some men with confirmed hypogonadism, but it is not a general anti-aging treatment or a substitute for evaluating sleep, metabolic health, medications, or mood. The FDA approves testosterone products for men with low testosterone associated with specific medical conditions and retains a limitation of use for age-related hypogonadism.
Fertility belongs in the conversation before treatment. Testosterone from outside the body can suppress the brain signals that support sperm production and may greatly reduce sperm count. The Endocrine Society recommends against starting testosterone in men planning fertility in the near term. Men who want children should ask about evaluation and alternatives that preserve reproductive goals.
Monitoring depends on the person and product. It may include symptom response, testosterone levels, blood count or hematocrit, prostate-related assessment when appropriate, and blood pressure. In 2025, the FDA removed boxed-warning language about increased major cardiovascular events after reviewing the TRAVERSE trial, while requiring class-wide warnings about increased blood pressure. That update does not make treatment risk-free or eliminate the need for individualized screening.
Before deciding, ask about the exact formulation, dose, potential benefits, side effects, fertility impact, cost, ability to adjust or stop treatment, and follow-up plan. Our guides to hormone replacement therapy costs in Arizona and HRT versus BHRT terminology provide useful questions for that discussion.
Kristen Salzwedel, NMD, has additional education in endocrinology and hormones and works with both men and women with endocrine and hormonal conditions at Live Well. Her profile explains her training and patient-centered approach.
Frequently asked questions
What are the most common symptoms of low testosterone in men over 40?
Possible symptoms include reduced sex drive, fewer spontaneous erections, erectile difficulty, reduced energy, loss of muscle mass, infertility, irritability, low mood, or concentration problems. These concerns overlap with other conditions and do not confirm low testosterone alone.
Is low testosterone a normal part of aging?
Levels may decline gradually with age, but age alone does not establish hypogonadism or automatically justify treatment. Diagnosis requires compatible symptoms or signs and consistently low, accurately measured testosterone.
What testosterone level is considered low?
The AUA uses total testosterone below 300 ng/dL as a reasonable cutoff supporting diagnosis, but laboratory ranges and clinical context vary. Symptoms plus at least two separate early-morning measurements are needed.
Can low testosterone cause erectile dysfunction?
It can contribute, especially when low desire or fewer spontaneous erections are present. Blood-vessel disease, diabetes, medications, nerve problems, thyroid disease, stress, and anxiety are also common causes.
Can testosterone therapy affect fertility?
Yes. Testosterone taken from outside the body can suppress the signals needed to make sperm and may substantially reduce fertility. Discuss current and future fertility goals before beginning treatment.
Discuss your symptoms and testing with a clinician
Bring your symptom timeline, medication and supplement list, previous laboratory results, and fertility goals to an individualized evaluation at Live Well in Chandler.
Book an AppointmentSources
- Endocrine Society: Statement on Testosterone Replacement Therapy
- Endocrine Society: Testosterone Therapy for Hypogonadism Guideline Resources
- Endocrine Society: Hypogonadism in Men
- American Urological Association: Testosterone Deficiency Guideline
- National Institute of Diabetes and Digestive and Kidney Diseases: Erectile Dysfunction Symptoms and Causes
- U.S. Food and Drug Administration: Class-Wide Labeling Changes for Testosterone Products
Medical disclaimer: This article is for general educational purposes and is not a diagnosis or a substitute for individualized medical advice. Testosterone symptoms, test results, treatment benefits, and risks vary. Do not start, stop, or change hormone therapy without guidance from a qualified healthcare professional.