Signs of Low Testosterone in Men: Symptoms Worth Getting Checked

Medically reviewed by William "Billy" Kimbrell, APRN · Last reviewed September 2026

Low testosterone can affect sex drive, energy, mood, muscle, and more. The more specific signs are sexual: a drop in libido, fewer morning erections, and erectile problems. Other symptoms like low energy, reduced muscle, more body fat, and trouble concentrating are real but far less specific, because they overlap with many other conditions. That is why you cannot diagnose low testosterone from symptoms alone.

EliteRx provider Brian Herbert on why "normal" labs don't always mean normal, and the difference between total and free testosterone.

So the useful question is not "do I have one symptom of low testosterone?" It is "has a pattern of things changed enough that testosterone testing makes sense?" This article walks through the signs, separates the specific from the vague, and covers what else can feel exactly like low testosterone.

What does low testosterone feel like?

There is no single "low testosterone feeling." Some men do not describe it as a sexual problem at all at first. They say they feel flat, sluggish, or less like themselves: less interested in sex, less motivated to train, slower mentally, running on empty even after a full night's sleep. Others notice the sexual changes first and everything else second.

And some men with laboratory-confirmed low testosterone have few obvious symptoms. Low testosterone is sometimes first discovered during an evaluation for infertility in a man who otherwise felt relatively normal. That variability is exactly why the diagnosis rests on the overall clinical picture plus blood testing, not on matching a feeling to a checklist.

Sexual signs of low testosterone

These come first because they are the most specific clinically. Major guidance, including the Endocrine Society's symptom framework, treats the sexual symptoms as the more telling ones.

Lower sex drive

A meaningful, persistent drop in libido is one of the classic and more specific signs of low testosterone. Sex drive can fall for many reasons (stress, relationship factors, medications, depression), but a clear change from your own normal is worth paying attention to.

Fewer morning or spontaneous erections

A noticeable decline in spontaneous erections, including waking erections, is one of the more specific signs of testosterone deficiency. Many men notice this before anything else.

Erectile dysfunction

Low testosterone can contribute to erectile dysfunction, but here is the important nuance: most ED is not primarily a testosterone problem. Erections depend on blood flow, nerves, medications, and psychological factors as much as hormones. ED is worth evaluating rather than assuming it points to testosterone, and it is often best looked at alongside men's sexual health as a whole. See erectile dysfunction symptoms and causes for the fuller picture.

Fertility problems or low sperm count

Low testosterone can occur alongside impaired sperm production or infertility, depending on the underlying cause. One thing worth knowing early: if future fertility matters to you, raise that before any hormone treatment is considered, because testosterone therapy can suppress sperm production, and guidelines advise against starting it in men who are planning children in the near term.

Physical signs of low testosterone

Loss of muscle mass and strength

Low testosterone may contribute to reduced muscle mass, strength, and endurance. But "I can't gain muscle" is not, by itself, a sign of low testosterone, training, nutrition, sleep, and recovery drive most of that, and plenty of men with normal testosterone struggle to build muscle.

Increased body fat

Increased body fat, particularly around the middle, is associated with low testosterone. It is also associated with age, calorie balance, activity level, sleep, medications, and metabolic health, so it is a weak signal on its own.

Reduced body or facial hair

Reduced beard growth or loss of underarm and pubic hair can occur with significant androgen deficiency. Note this is different from male-pattern baldness, which is a separate hair-follicle and genetics story, not the same thing as low testosterone.

Smaller testicles

Shrinking or small testicles is one of the more suggestive physical signs, and it is one a provider may specifically look for during an evaluation.

Breast tissue changes

Gynecomastia, or enlargement of male breast tissue, can occur in some men with hormone imbalance or hypogonadism. It is not specific to low testosterone and has other possible causes, so it is one more reason to evaluate rather than assume.

Hot flashes

Most men do not associate hot flashes with testosterone, but they can occur with significant testosterone deficiency. Because it is uncommon and unexpected, it is a genuinely useful clue when it does show up.

Bone loss

Longstanding, significant testosterone deficiency can contribute to reduced bone density over time. This is usually a longer-term consequence rather than an early symptom you would notice day to day.

Mental and energy symptoms

These are real, but they are the least specific, which the sections below take seriously rather than glossing over.

Persistent fatigue or low energy

Low energy can occur with low testosterone, but it is one of the least specific symptoms there is. Before assuming testosterone, it is worth remembering how many common things cause the same fatigue: insufficient or fragmented sleep, sleep apnea, depression, thyroid disease, diabetes, anemia, stress, and a range of medications.

Low motivation or feeling "flat"

Some men describe less drive or initiative, or less interest in things they normally enjoy. This is real and worth taking seriously, but it overlaps substantially with depression, poor sleep, and chronic stress, so it is not an endocrine diagnosis by itself.

Trouble concentrating or memory changes

Difficulty concentrating and memory changes are on the recognized symptom list, but they are nonspecific and share a long list of causes. Worth mentioning to a provider, not worth self-diagnosing from.

Depressed mood

Low testosterone is associated with depressed or flat mood. Depression itself, though, produces many of the same complaints, low energy, low libido, poor concentration, so mood changes are a reason to look carefully, not a reason to conclude testosterone is the cause.

The symptoms most likely to point toward low testosterone

Not all symptoms carry equal weight. Clinical guidance separates the more specific signs from the ones that, on their own, could come from almost anything. This split is the single most useful thing to understand:

Can you have low testosterone without sexual symptoms?

Yes. Sexual symptoms are among the more specific clues, but they are not mandatory. Men can present differently, some mainly notice energy, mood, or body-composition changes, and a few have very low measured testosterone with few obvious symptoms at all. That is one more reason diagnosis relies on the overall clinical picture combined with blood testing rather than any one symptom.

What can feel like low testosterone but isn't?

This is the part worth slowing down on, because a lot of what gets blamed on testosterone turns out to be something else, and some of these conditions can even lower testosterone themselves. Things that can produce very similar symptoms include:

• Poor sleep or sleep apnea, which cause fatigue, low mood, poor focus, and sexual problems, and are themselves linked to lower testosterone.
• Depression and anxiety, which overlap heavily with the "flat, low-drive, low-energy" picture.
• Thyroid problems, which affect energy, mood, and weight.
• Diabetes and metabolic disease, and obesity, which are strongly tied to both symptoms and low testosterone.
• Medication effects, including opioids and some others.
• Acute or chronic illness, and heavy alcohol or substance use.

Can low testosterone happen in younger men?

Yes. Low testosterone becomes more common with age, but it can occur at any age because of testicular problems, pituitary or hypothalamic issues, genetic conditions, medications, or other medical causes. Being in your thirties does not rule it out. If you want to understand how levels shift across the decades, see normal testosterone levels by age.

How do you know if you actually have low testosterone?

You do not diagnose it from a symptom checklist. The actual path is: compatible symptoms and signs, an early-morning total testosterone blood test, a low result confirmed with a second morning test, and then additional testing to understand the cause when it is warranted. The Endocrine Society is explicit that diagnosis requires symptoms and consistently low, accurately measured testosterone.

If your symptoms have you wondering, the next step is understanding the test itself, see how to test your testosterone, and then what the result means, which is covered in normal testosterone levels by age. Together those walk you from symptoms to a real answer.

What happens if low testosterone goes untreated?

It depends on why it is low, how low it is, and what symptoms or complications are present. Significant, persistent low testosterone can contribute to ongoing sexual symptoms, reduced muscle mass, lower bone density over time, and fertility problems depending on the cause. But not every low reading requires treatment, the importance of treating depends on the full picture, which is why the cause matters as much as the number.

Can lifestyle changes raise low testosterone?

Sometimes. Lifestyle can improve testosterone in some men, especially when excess weight, poor sleep, or metabolic health are contributing factors. The fundamentals that help overall hormonal health include reaching a healthy weight, regular physical activity, adequate sleep, treating sleep apnea, a nutritious diet, and avoiding excess alcohol. What lifestyle cannot do is correct every cause of low testosterone, if the cause is testicular or pituitary, better habits alone will not fix it. Both experiences are common: some men normalize with lifestyle changes, others do not, and that difference usually comes down to the underlying cause.

Does having low testosterone mean you need TRT?

No. Confirmed testosterone deficiency calls for figuring out the cause and discussing appropriate options. Testosterone therapy may be right for some men; for others, treating an underlying cause or taking a different approach makes more sense. Treatment eligibility cannot be determined from symptoms, or from a single testosterone value. If it does turn out to be appropriate, that is a conversation about testosterone therapy and hormone care, decided for you specifically.

Frequently asked questions

What are the first signs of low testosterone in men?

The most specific signs tend to be sexual: a drop in sex drive, fewer spontaneous or morning erections, and erectile problems. Less specific changes like fatigue, low motivation, reduced muscle, and mood changes can also occur, but they overlap with other conditions and are not diagnostic on their own.

Can you tell if a man has low testosterone by looking at him?

No. Some suggestive physical signs like reduced body hair or smaller testicles can occur with significant deficiency, but low testosterone is confirmed with blood testing plus symptoms, not by appearance.

How does low testosterone make a man feel?

There is no single feeling. Some men notice reduced sexual desire; others mainly feel flat, sluggish, unmotivated, or slower mentally. Some have few obvious symptoms at all, which is why diagnosis relies on the overall picture plus blood testing.

Does low testosterone always cause erectile dysfunction?

No. It can contribute to ED, but most ED is not caused by low testosterone. ED has many causes and should be evaluated rather than assumed to be a testosterone problem.

Can you have low testosterone and still have a sex drive?

Yes. Sexual symptoms are among the more specific clues but are not required. Some men with confirmed low testosterone keep their libido and present in other ways.

Does low testosterone cause weight gain?

It is associated with increased body fat, but the relationship runs both ways, excess weight can also lower testosterone. Weight change alone is not proof of low testosterone.

Can low testosterone cause depression or anxiety?

It is associated with depressed or flat mood, but depression and anxiety have many causes and can produce the same symptoms. That overlap is why mood changes alone do not diagnose it.

What age do men start getting low testosterone?

Levels tend to decline gradually with age, but clinical low testosterone can occur at any age due to testicular, pituitary, genetic, medication-related, or other causes. There is no fixed starting age.

What happens if low testosterone goes untreated?

It depends on the cause, how low it is, and the symptoms present. Significant, persistent low testosterone can contribute to ongoing sexual symptoms, reduced muscle, lower bone density, and fertility problems. The right response is to find the cause, not to assume treatment is always needed.

How do you test for low testosterone?

With an early-morning total testosterone blood test, confirmed by a second morning test if the first is low, and read alongside your symptoms. See how to test your testosterone for the full walkthrough.