Low Testosterone Symptoms

Low testosterone affects an estimated 4-5 million American men, but research suggests only about 5% receive treatment. That's partly because the symptoms are easy to attribute to aging, stress, or just life—and partly because many men never get tested.

Here's what you need to know: not every symptom is equally suggestive of low testosterone. Medical guidelines distinguish between "specific" symptoms (more likely to indicate low T) and "nonspecific" symptoms (could be many things). Understanding this distinction helps you have a more productive conversation with your doctor.

Specific Symptoms (More Likely to Indicate Low T)

These symptoms are more directly linked to testosterone deficiency. If you have several of these, testing is reasonable even without other risk factors.

Reduced Sex Drive (Libido)

This is one of the most consistent symptoms of low testosterone. We're not talking about occasionally not being in the mood—we're talking about a noticeable, persistent decline in sexual interest that represents a change from your baseline.

Testosterone plays a direct role in sexual desire. Men with low T often describe feeling like "the switch just turned off" rather than a gradual decline.

Erectile Dysfunction

While testosterone isn't the only factor in erections (blood flow, nerve function, and psychology all matter), low T can contribute to ED. More specifically, low testosterone is associated with loss of spontaneous erections (like morning wood) and difficulty maintaining erections.

Important caveat: ED is extremely common and has many causes. If you have ED but no other low T symptoms, testosterone probably isn't the issue.

Loss of Spontaneous Erections

Specifically, the absence or reduction of morning erections (nocturnal penile tumescence). These happen during REM sleep and are a sign that the physical plumbing is working. If you used to wake up with erections and now rarely do, that's worth noting.

Reduced Testicular Size

The testicles produce testosterone, and low testosterone can cause them to shrink. If you've noticed your testicles getting smaller, this is a specific indicator worth investigating.

Hot Flashes

Yes, men can get hot flashes. Low testosterone can cause sudden sensations of heat, especially in the face and upper body. If you're experiencing this, it's a relatively specific sign of hormonal changes.

Loss of Body Hair

Testosterone maintains body hair. If you're losing axillary (armpit) or pubic hair, or noticing reduced facial hair growth, this could indicate low T. Pattern baldness on your head is different—that's driven by DHT and genetics, not low testosterone.

Infertility

Low testosterone can lead to reduced sperm production. If you're having difficulty conceiving, testosterone levels should be part of the workup.

Nonspecific Symptoms (Could Be Many Things)

These symptoms are associated with low testosterone but have many other possible causes. On their own, they don't strongly suggest low T—but combined with specific symptoms, they paint a fuller picture.

Fatigue and Low Energy

Feeling tired all the time is one of the most commonly reported symptoms in men who turn out to have low testosterone—but it's also one of the most common complaints in general medicine. Sleep issues, depression, thyroid problems, anemia, and dozens of other conditions cause fatigue.

Low T fatigue is often described as feeling "drained" or lacking motivation, even with adequate sleep. It's different from sleepiness.

Depressed Mood

Low testosterone is associated with depressive symptoms, including low mood, irritability, and difficulty experiencing pleasure. The relationship is bidirectional—depression can lower testosterone, and low testosterone can contribute to depression.

If you're experiencing depression, it's worth getting testosterone checked as part of a comprehensive evaluation, but low T is rarely the only factor.

Difficulty Concentrating

Some men with low testosterone report "brain fog," difficulty focusing, or reduced mental clarity. These cognitive symptoms are real but nonspecific.

Decreased Muscle Mass and Strength

Testosterone is anabolic—it helps build and maintain muscle. Low T can lead to reduced muscle mass and strength, even with regular exercise. You might notice you're not progressing in the gym despite consistent training.

Increased Body Fat

Low testosterone is associated with increased body fat, particularly visceral (abdominal) fat. Some men also develop gynecomastia (breast tissue growth) due to an altered testosterone-to-estrogen ratio.

Sleep Disturbances

Low T is linked to sleep problems, including insomnia. However, sleep apnea—which is common in overweight men—can itself cause low testosterone, creating a chicken-and-egg situation.

Who's at Higher Risk?

Certain conditions significantly increase your likelihood of having low testosterone:

Other risk factors include:

• Opioid use (prescription or otherwise)
• Sleep apnea
• Testicular injury or cancer treatment
• Pituitary disorders
• Chronic kidney or liver disease
• Use of certain medications (corticosteroids, some antidepressants)

How Low Testosterone Is Diagnosed

Medical guidelines require both blood test confirmation and symptoms for a diagnosis of hypogonadism (low testosterone that warrants treatment).

The Blood Test

Testosterone levels fluctuate throughout the day, peaking in the morning. Testing should be done between 7-10 AM. Because levels can vary from day to day, a diagnosis requires two separate morning blood tests showing low levels.

The American Urological Association defines low testosterone as a total testosterone level below 300 ng/dL. However, some men have symptoms even with levels in the 300-400 range, and treatment decisions often depend on the full clinical picture.

Beyond Total Testosterone

Total testosterone isn't the whole story. Some testosterone is bound to proteins (SHBG and albumin) and isn't biologically active. If your total testosterone is borderline but you have symptoms, your doctor may check free testosterone or bioavailable testosterone for a more complete picture.

Additional Testing

If low T is confirmed, additional tests help identify the cause:

• LH and FSH — Distinguish between testicular problems (primary) vs. pituitary/brain problems (secondary)
• Prolactin — High levels may indicate a pituitary issue
• CBC — Check for anemia
• Metabolic panel — Diabetes and metabolic issues

When to Get Tested

Consider getting your testosterone checked if:

• You have multiple specific symptoms (reduced libido, ED, loss of morning erections)
• You have nonspecific symptoms plus risk factors (obesity, diabetes, opioid use)
• You're experiencing unexplained changes in mood, energy, or body composition
• You've been diagnosed with a condition associated with low T
• You want to rule it out as part of understanding symptoms

Routine screening in men without symptoms is not recommended—but if you're reading this article because something feels off, testing is a reasonable step.

The Bottom Line

Low testosterone is real, underdiagnosed, and treatable. But many of its symptoms overlap with other conditions—including normal aging, depression, sleep problems, and metabolic issues.

The path forward is simple: if you have symptoms that concern you, get tested. A blood test takes the guesswork out of the equation. If your testosterone is normal, you can explore other explanations. If it's low, you have information that can genuinely improve your quality of life.

Don't assume symptoms are "just aging." Don't assume they must be low T either. Get data and work with a provider who can interpret it in context.