Low Testosterone Symptoms in Men and How to Confirm a Low Level

Low testosterone can cause low sex drive, erection changes, low energy, mood changes, loss of muscle, and weaker bones. Learn which symptoms matter, what causes low T, and why two morning blood tests are needed before calling a level low.

Published

September 28, 2026

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9 min read

Medically reviewed by

Rhonda Collins, FNP-C

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Common symptoms of low testosterone in men are a lower sex drive, erectile dysfunction, fewer spontaneous or morning erections, low energy, low mood or irritability, trouble concentrating, loss of muscle mass, more body fat, and, over time, weaker bones. None of these symptoms is specific to testosterone. Stress, poor sleep, depression, and other medical conditions can cause the same changes, so symptoms alone cannot tell you whether your testosterone is low. Endocrine Society: Hypogonadism in Men; AUA testosterone deficiency guideline.

Low testosterone, also called testosterone deficiency or male hypogonadism, is diagnosed only when typical symptoms or signs occur together with consistently low total testosterone on blood tests taken early in the morning on two separate days. AUA testosterone deficiency guideline.

This page covers symptoms, causes, and how a low result is confirmed. For laboratory reference ranges, see normal testosterone levels by age. For what total testosterone measures, see the total testosterone biomarker overview.

Symptoms and Signs of Low Testosterone in Men

Low testosterone symptoms fall into a few groups. The Endocrine Society and MedlinePlus list the following as symptoms and signs that can occur with low testosterone. Endocrine Society: Hypogonadism in Men; MedlinePlus: Testosterone Levels Test.

Sexual symptoms

• Lower sex drive (libido).
• Erectile dysfunction, including fewer spontaneous or early-morning erections.
• Lower sperm count and difficulty conceiving.

Energy, mood, and concentration

• Reduced energy and fatigue.
• Irritability, depressed mood, and difficulty concentrating.
• Hot flashes, usually only when testosterone is very low.

Body composition

• Loss of muscle mass.
• More body fat, especially around the abdomen.
• Breast enlargement or tenderness.
• Loss of body or facial hair over time.

Bone and blood

• Thinning bones (lower bone density or osteoporosis) over time, which raises the risk of fractures.
• Anemia (low red blood cells) without another clear cause.

The American Urological Association (AUA) notes that fatigue, low mood, loss of muscle, more fat (especially abdominal fat), erectile dysfunction, and low sex drive can also come from chronic stress, chronic fatigue, or depression, and that fatigue in particular is non-specific. It also notes that erectile dysfunction often travels with diabetes and obesity, which are themselves linked to low testosterone. AUA testosterone deficiency guideline.

Symptom questionnaires do not settle the question either. The AUA does not recommend using them to decide who has testosterone deficiency. AUA guideline statement 5.

What Causes Low Testosterone

Low testosterone has two broad sources. Primary hypogonadism means the testes themselves make too little testosterone. Secondary (central) hypogonadism means the hypothalamus or pituitary gland in the brain does not send a strong enough signal to the testes. MedlinePlus: Hypogonadism.

Common and important causes include:

• Age. Testosterone declines gradually with age, by about 1% a year after age 30 according to the Endocrine Society, though it usually does not fall severely in healthy older men. Endocrine Society: Hypogonadism in Men.
• Obesity and type 2 diabetes. The Endocrine Society estimates that 30 to 50% of men with obesity or type 2 diabetes have hypogonadism. The AUA cites pooled data in which men with obesity were almost five times as likely to have low testosterone as men without obesity. Endocrine Society; AUA guideline.
• Obstructive sleep apnea. A 2022 meta-analysis of 18 studies in 1,823 men found lower testosterone in men with obstructive sleep apnea, independent of age and body mass index, with the clearest reduction in severe sleep apnea. The studies show an association, not proof that sleep apnea causes low testosterone. Su et al., Andrology 2022.
• Medications. Opioid pain medicines and glucocorticoids (corticosteroids) can suppress the signal from the brain to the testes. Stopping anabolic steroids after use can also leave testosterone low. MedlinePlus: Hypogonadism; Endocrine Society.
• Heavy training with too little fuel. In endurance-trained men, low energy availability (not eating enough to cover training) has been linked with lower testosterone and bone density. Cupka and Sedliak, Eur J Transl Myol 2023. Our article on low testosterone and overtraining covers this angle in more depth.
• Testicular and pituitary conditions. Testicular injury or infection, chemotherapy or radiation, pituitary tumors, high prolactin, and genetic conditions such as Klinefelter syndrome can all cause low testosterone. Endocrine Society.
• Chronic illness. Liver disease, kidney disease, and HIV are also associated with low testosterone. Endocrine Society.

Some of these causes, such as obesity, can improve without testosterone therapy, and the Endocrine Society says they should be addressed first. For evidence on lifestyle factors, see our guide to raising testosterone naturally. Endocrine Society.

Why Symptoms Alone Cannot Diagnose Low Testosterone

Low testosterone is a diagnosis that needs both symptoms or signs and a confirmed low blood level. Symptoms without a low level, or a single low number without symptoms, do not meet the definition. Both the AUA and the Endocrine Society set out the same basic steps.

Two early-morning total testosterone tests. The AUA recommends diagnosing low testosterone only after two total testosterone measurements taken on separate occasions, both early in the morning. The Endocrine Society recommends a fasting morning total testosterone test, then a repeat fasting morning test to confirm a low result. AUA guideline statements 1 to 3; Endocrine Society guideline, 2018.

Morning timing matters because testosterone is usually highest early in the day, and levels vary from one day to the next. MedlinePlus notes that blood for a testosterone test is usually taken in the morning, between 7 and 10 a.m. MedlinePlus: Testosterone Levels Test; Endocrine Society guideline, 2018.

The AUA 300 ng/dL cutoff. The AUA uses a total testosterone below 300 ng/dL as a reasonable cutoff that supports a diagnosis of low testosterone in men. The AUA panel based that cutoff on at least two early-morning levels measured at the same laboratory with the same assay. A value below 300 ng/dL is not a diagnosis by itself: the AUA says the clinical diagnosis is made only when low total testosterone is combined with symptoms or signs. AUA testosterone deficiency guideline.

This cutoff is a clinical threshold, not the reference range printed on your lab report. The normal testosterone levels by age guide explains how the two differ.

Follow-up tests look for the cause. Once testosterone is confirmed low, the AUA recommends measuring luteinizing hormone (LH) to help separate testicular from brain-signal causes, and prolactin when LH is low or low-normal. AUA guideline statements 6 and 7.

When Free Testosterone and SHBG Add Context

Total testosterone includes testosterone bound to proteins and the small unbound fraction. Free testosterone is the unbound part. Much of the rest is bound to sex hormone-binding globulin (SHBG).

When SHBG is unusually high or low, total testosterone can give a misleading picture of how much testosterone is available. The Endocrine Society recommends measuring free testosterone in men whose total testosterone is near the lower limit of normal, or who have a condition that alters SHBG. It recommends measuring free testosterone by equilibrium dialysis or estimating it with an accurate formula. Endocrine Society guideline, 2018.

MedlinePlus explains the direction of the effect. Low SHBG, which is linked to obesity, type 2 diabetes or insulin resistance, and hypothyroidism, means more of total testosterone is likely free. A low total result in a man with obesity may therefore overstate how little testosterone is available. High SHBG, which is linked to liver disease among other conditions, means less of total testosterone is available to tissues, so a normal-looking total can hide a low free level. MedlinePlus: SHBG Blood Test.

That is why a borderline total testosterone result, or any result in a man with a condition that changes SHBG, often needs free testosterone and SHBG before anyone draws a conclusion.

How to Test for Low Testosterone

A useful testosterone test follows the same rules the guidelines use: collect early in the morning, repeat a low result on a different day, and compare results on the same kind of test.

Mito offers two ways to measure total testosterone:

• The At-Home Testosterone Test Kit measures total testosterone from a sample you collect at home. Its product page asks you to collect in the morning when possible and at a similar time for repeat tests. It measures total testosterone only. It does not include free testosterone, SHBG, or LH.
• The Testosterone, Total Blood Test measures total testosterone from a blood draw at an accredited lab near you. Because the guidelines above call for early-morning samples, an early appointment gives a result you can compare with them.

If a result comes back low, repeat it on another morning with the same test before treating it as confirmed. The at-home testosterone test guide explains how home collection compares with a lab draw. Both product pages state that a clinician reviews your results, which can help you decide whether free testosterone, SHBG, LH, or other markers are the right next step.

When to See a Clinician About Low Testosterone Symptoms

See a clinician if you have ongoing low sex drive, erection problems, or other symptoms above, especially together with a low morning result, bone density loss, unexplained anemia, infertility, breast enlargement, or headaches and vision changes, which can point to a pituitary problem. MedlinePlus: Hypogonadism; AUA guideline statement 4.

Treatment choices, including testosterone replacement therapy, depend on the cause, fertility plans, and other health factors, and are managed by a prescribing clinician. Our testosterone replacement therapy guide explains how TRT works.

Frequently Asked Questions

What is usually the first sign of low testosterone?

There is no single first sign that applies to everyone. Lower sex drive and fewer spontaneous or morning erections are common early complaints, while fatigue and low mood are common but can have many other causes.

At what age do low testosterone symptoms start?

Testosterone declines gradually from around age 30, but most healthy older men do not develop severely low levels. Symptoms can appear at any adult age when a cause such as obesity, sleep apnea, opioid use, or a testicular or pituitary condition is present.

Can low testosterone cause weight gain?

Low testosterone is associated with more body fat and less muscle. The link runs both ways, because obesity also lowers testosterone, so weight gain alone does not show which came first.

Can low testosterone cause anxiety or depression?

Low testosterone can occur with irritability, depressed mood, and poor concentration. Depression and chronic stress can cause the same symptoms on their own, which is why a confirmed low morning level is needed before attributing them to testosterone.

Can women have low testosterone symptoms?

Yes, testosterone matters in women too, but female ranges and symptoms differ and the 300 ng/dL male cutoff does not apply. This page focuses on men.

References

• American Urological Association: Evaluation and Management of Testosterone Deficiency (2018)
• Bhasin S, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018
• Endocrine Society: Hypogonadism in Men
• MedlinePlus: Testosterone Levels Test
• MedlinePlus: Hypogonadism
• Su L, et al. Association between obstructive sleep apnea and male serum testosterone: a systematic review and meta-analysis. Andrology. 2022
• Cupka M, Sedliak M. Hungry runners: low energy availability in male endurance athletes and its impact on performance and testosterone. Eur J Transl Myol. 2023

Related Resources

• Normal testosterone levels by age
• Total testosterone biomarker overview
• High free testosterone symptoms
• Raising testosterone naturally
• Low testosterone and overtraining
• What is testosterone replacement therapy?