The most common symptoms of low testosterone in men are low sex drive, erectile difficulties, ongoing fatigue, loss of muscle mass, increased belly fat, mood changes, brain fog, and poor sleep. If several show up at once and last for weeks or months, a simple morning blood test can tell you whether testosterone is actually the problem – or whether something else, like thyroid disease, sleep apnea, or depression, is behind it.
At EverHeal Medical in Los Angeles, testosterone concerns are evaluated the way any other medical condition is: with a history, an exam, and lab work – not guesswork. The signs of low testosterone are often mistaken for stress or the inevitable effects of aging.
Testosterone is the primary male sex hormone. It’s made mostly in the testicles, and production is controlled by signals from the brain – the hypothalamus and pituitary gland. Its role extends far beyond the bedroom.
Testosterone is responsible for:
Developing and maintaining muscle mass and strength
Regulating body fat distribution
Maintaining bone density
Driving libido (sex drive)
Producing sperm
Stimulating red blood cell production
Influencing energy, mood, and mental sharpness
Levels peak in the late teens and twenties, then decline roughly 1% per year after about age 30. That slow slide is normal. What isn’t normal is a level low enough to cause real symptoms – a condition doctors call hypogonadism or testosterone deficiency.
Two things matter here. First, low testosterone can happen at any age, not just after 50. Second, a low number on a lab report by itself isn’t a diagnosis – symptoms plus confirmed low levels on at least two morning blood draws are what make the diagnosis.
Low testosterone can also be secondary to other issues: obesity, poorly controlled diabetes, untreated sleep apnea, thyroid disorders, chronic opioid or steroid use, or significant stress. Finding the cause changes the treatment plan.
Symptoms of low testosterone in men fall into three buckets: sexual, physical, and emotional/mental. Most men who turn out to have testosterone deficiency have symptoms in more than one bucket at the same time. A single symptom in isolation is much less telling.
Sexual symptoms are the most specific signs of testosterone deficiency, meaning they’re the least likely to be explained by something unrelated.
Reduced sexual desire is the single most common complaint men bring in with. This isn’t an occasional off week – it’s a persistent drop in interest, fewer sexual thoughts, less initiation, less spontaneous desire, noticeably different from your own baseline a year or two ago.
Men often describe it as “the switch just isn’t flipping anymore,” and partners frequently notice before the patient does. Because desire is also affected by relationship stress, depression, medications (especially certain antidepressants and blood pressure drugs), and alcohol, a good evaluation sorts through all of it rather than assuming hormones are the cause.
Testosterone doesn’t cause erections on its own, but it stimulates receptors in the brain to produce nitric oxide and supports the nerve and blood vessel signaling that makes erections possible. Low levels can make erections weaker, less reliable, or harder to maintain.
An important distinction: men with low testosterone often lose desire first, then notice erection problems. Men whose erectile dysfunction stems from blood flow problems – high blood pressure, high cholesterol, diabetes, smoking – usually still want sex but can’t perform. That difference is a real clue, and it’s why erectile dysfunction always deserves a cardiovascular workup, not just a hormone panel.
Testosterone contributes to the production of seminal fluid, which aids sperm motility. Men with low levels often notice a smaller ejaculate volume over time. It rarely affects pleasure, and many men don’t think to mention it – but it’s worth reporting.
Low testosterone can also reduce sperm production and affect fertility. This matters enormously for treatment planning: testosterone replacement therapy suppresses the body’s own sperm production and can cause temporary or, in some cases, lasting infertility. Any man who might want children needs that conversation before starting therapy.
The physical changes build slowly, which is why they’re so often blamed on aging or a busy schedule.
Loss of muscle mass and strength. Testosterone drives muscle protein synthesis. When it drops, the same gym routine stops producing results, size and strength fade despite consistent training, and recovery between workouts takes longer.
Increased body fat, especially around the middle. Abdominal fat contains an enzyme called aromatase that converts testosterone into estrogen, which further lowers testosterone and promotes more fat gain. Breaking that cycle sometimes requires addressing weight directly, which is why medical weight loss and hormone evaluation often go hand in hand.
Persistent fatigue. Not sleepiness – a deeper sense of being drained that doesn’t improve with rest. Men describe hitting a wall in the early afternoon, needing naps they never needed, or feeling the reserve tank is simply gone.
Reduced bone density. It often goes unnoticed until an unexpected fracture from a minor fall.
Hot flashes and night sweats. Less common but real, especially when testosterone drops sharply rather than gradually.
Anemia. Testosterone stimulates red blood cell production; unexplained mild anemia on routine bloodwork occasionally traces back to low levels.
Breast tenderness or enlargement. Called gynecomastia, this reflects a shifted testosterone-to-estrogen ratio.
These are the symptoms men are least likely to bring up and most likely to dismiss.
Low mood and irritability. Some men feel flat and unmotivated; others feel short-tempered and quick to snap. Because these overlap heavily with clinical depression – and because low testosterone and depression can each cause the other – careful evaluation matters. Our approach to mental health care considers hormonal contributors rather than treating mood in isolation.
Brain fog and poor concentration. Difficulty focusing, losing your train of thought mid-sentence, trouble recalling information, or a sense that your thinking is slower than it used to be.
Reduced motivation and drive. Many men describe losing their competitive edge – at work, in the gym, in life generally.
Sleep disruption. Trouble falling asleep, waking repeatedly, or waking unrefreshed. This cuts both ways: poor sleep lowers testosterone, and low testosterone worsens sleep. Untreated sleep apnea is one of the most commonly missed causes of low testosterone, which is why screening for it is routine in a thorough workup.
Some presentations don’t fit the classic picture at all:
Unexplained joint or muscle aches without injury or arthritis findings
Reduced exercise tolerance and endurance – getting winded on activities that used to be easy, and taking longer to recover
Changes in body odor or sweating patterns
Loss of height over the years, which can signal vertebral bone loss
Worsening blood sugar control in men with diabetes or prediabetes, since low testosterone is associated with insulin resistance
Anxiety that’s new in mid-life with no clear trigger
Loss of confidence or a sense of diminished masculinity – vague, hard to describe, but frequently reported
Younger men can also have low testosterone, and it often gets missed. Anabolic steroid use (past or present), significant obesity, chronic opioid therapy, head injury, chemotherapy, certain genetic conditions, and pituitary problems can all cause it in men in their twenties and thirties.
Get evaluated if you have several of these symptoms lasting more than a few weeks – particularly if any specific signs are present, and especially if they’re affecting your daily life, relationships, or sense of well-being. Don’t dismiss it as just “getting older.”
Screening is also worthwhile if you have type 2 diabetes, obesity, osteoporosis, HIV, chronic kidney disease, or a history of steroid or long-term opioid use – all groups with higher rates of testosterone deficiency.
A morning blood draw, ideally between 7 and 10 a.m., when levels peak
Confirmation on a second morning sample – one low result isn’t enough
A complete workup: total testosterone, free testosterone, LH, FSH, prolactin, complete blood count, PSA in appropriate age groups, thyroid function, and metabolic markers
At EverHeal Medical, our team evaluates men’s hormone concerns as part of full-spectrum primary care – meaning the same visit can address blood pressure, cholesterol, blood sugar, thyroid, and sleep, all of which interact with testosterone. Depending on findings, options may include:
Treating an underlying cause
Lifestyle and weight interventions
Hormone therapy, including Testosterone Replacement Therapy
The symptoms of low testosterone in men fall into three groups: sexual (low desire, erectile changes, reduced semen volume), physical (muscle loss, abdominal fat gain, fatigue, bone loss), and emotional (low mood, irritability, brain fog, poor sleep). Specific signs like lost morning erections and shrinking testicles point strongly toward a hormone problem; non-specific ones like fatigue need a wider investigation.
The only way to know for certain is confirmed morning lab testing paired with a real clinical evaluation. If what you’ve read here sounds familiar, that evaluation is the right next step.
Visit us: 1494 S Robertson Blvd, Los Angeles
Call: 310-692-9889
About the Author
Dr. Ebi Rowshanshad
