How Can I Tell If I Have Low Testosterone?
Most men with low testosterone notice a cluster of symptoms rather than one: persistent fatigue that sleep does not fix, weight gain around the middle, a drop in sex drive, loss of muscle, poor concentration and low mood. Symptoms alone cannot confirm it. A blood test is the only way to know.
What are the symptoms of low testosterone?
The symptoms we most often see in men who turn out to have clinically low testosterone are:
- Chronic fatigue — tiredness that rest does not resolve
- Weight increase — particularly around the abdomen
- Low libido — reduced sex drive, and often weaker erections
- Insomnia — difficulty sleeping, or waking unrefreshed
- Memory loss — poor concentration and mental fog
- Reduced muscle mass and strength — despite unchanged training
- Mood changes — irritability, flat mood, loss of motivation
These symptoms overlap with several other conditions, including thyroid disorders, sleep apnoea, depression and diabetes. That is why diagnosis depends on blood work rather than on how you feel.
Does low testosterone cause fatigue?
Yes. Fatigue is one of the most commonly reported symptoms of low testosterone. It tends to be persistent rather than occasional, and it is not corrected by more sleep. Men often describe it as a loss of drive or stamina rather than simple tiredness — they can get through the day, but the energy they used to have is gone.
Does low testosterone cause weight gain?
Testosterone influences how the body stores fat and maintains muscle, so low levels can make weight gain easier and fat loss harder — particularly around the abdomen. The relationship runs both ways: excess body fat can further lower testosterone, which is why the pattern can be difficult to break through diet and exercise alone.
We recommend a body composition analysis rather than relying on scale weight, so fat loss can be measured separately from muscle gain.
Does low testosterone affect sex drive and erections?
Reduced libido is among the most recognisable signs of low testosterone, and weaker or less frequent erections often accompany it. Erectile difficulties can have several causes — including cardiovascular and circulatory conditions — so they should be assessed properly rather than assumed to be hormonal.
Can low testosterone cause muscle loss?
Yes. Testosterone supports the maintenance of lean muscle, so men with low levels often notice strength falling and muscle becoming harder to build or hold, even with unchanged training. Many men describe getting less from the same effort in the gym.
Does low testosterone affect mood, memory and concentration?
Low mood, irritability, loss of motivation and difficulty concentrating are frequently reported. Men often describe mental fog, or finding focused work harder than it used to be. These symptoms are easy to attribute to stress or age, which is one reason low testosterone often goes untested for years.
Does low testosterone cause insomnia?
Disturbed sleep is a common complaint among men with low testosterone. Sleep and hormone levels are closely linked, and poor sleep can itself lower testosterone — so the two often reinforce each other. Sleep apnoea should be ruled out, as it both disrupts sleep and independently affects hormone levels.
At what age does testosterone start to decline?
Testosterone generally begins a gradual decline from around age 30, continuing slowly through life. That gradual change is normal. What is not normal is a level low enough to cause symptoms, and that can occur at any age — through natural causes, or as a result of other medical conditions.
Medical understanding has shifted here. It has long been accepted that women may need hormone support as they age; it is now equally recognised that men can too. Where levels are genuinely low, treating them to an optimal range is appropriate care.
What testosterone level is considered low?
The normal range is 300 to 1000 ng/dL. A number on its own cannot diagnose low testosterone, however. Age, body size and your symptoms all have to be considered alongside the result.
We look at your total testosterone, your free testosterone and your symptoms together. Two men with the same reading can need quite different care.
How is low testosterone diagnosed?
Diagnosis requires a blood test. Symptoms indicate that testing is worthwhile; they do not confirm the condition on their own.
At Prime Men’s Health the process is:
- A free consultation, by phone or online
- Comprehensive blood work, which can be completed at home using our blood spot lab kit
- A virtual visit with a physician, who reviews your results and determines whether treatment is appropriate
- If prescribed, treatment shipped directly to you
We also require our patients to have a primary care doctor who assesses their overall health, and we ask you to inform that doctor about any therapy you begin with us.
What lab tests are used to check for low testosterone?
We run standard lab tests alongside specific measures of total testosterone, free testosterone and estrogen. Our at-home blood spot kit also measures insulin, blood lipids, Vitamin D, thyroid hormones and elements such as magnesium — which matters, because several of those can produce symptoms that resemble low testosterone.
Before starting treatment we carry out a baseline PSA test, which screens for prostate risk. That test is repeated every six months during therapy, alongside a series of urinary questions.
How often will I need blood tests?
It depends on your age, weight, hormone levels at first testing, and your physician’s assessment. Once your optimal levels are established, you can expect lab work every six months.
What ages of men do you treat?
We generally treat men aged 30 or older who have both specific health concerns and objectively low lab values. Symptoms alone are not sufficient, and neither is a number without symptoms — we look for both.
If my levels are low, how quickly does treatment work?
This varies between individuals. Most men notice changes in energy, sex drive, erections and mood within two to three weeks of reaching optimal therapeutic levels. Benefits such as reduced joint pain, increased muscle strength and a broader sense of improved health are normally seen six to eight weeks after optimal therapy is achieved.
Treatment is a tool rather than a complete answer. If your goal is weight loss, diet and exercise remain necessary alongside therapy.
What should I do if these symptoms sound familiar?
Get tested. Symptoms of low testosterone overlap with several other treatable conditions, so a blood test is worth having whatever the answer turns out to be.
Prime Men’s Health offers a free consultation by phone or online, with at-home blood testing and virtual visits with a licensed physician. Testosterone therapy is available in 36 states and the District of Columbia, and enclomiphene therapy in all 50 states.
Call 1-800-530-7746 or book a free consultation.
Related reading
For independent information on this topic, see Cleveland Clinic guidance on low testosterone.
Medically reviewed by John Webb, MD, MBA on 28 September 2026. Dr. Webb completed a men’s health (Andrology) clinical research fellowship at Harvard Medical School and has nearly 20 years of experience in progressive healthcare leadership.
This page is general information and is not medical advice or a substitute for consultation, diagnosis or treatment by a licensed healthcare professional. Hormone therapy is available only following an evaluation with a licensed Prime Men’s Health provider, who determines eligibility and explains benefits and risks. Depending on federal and state regulations, your treatment plan may require an in-person physical examination.