Low testosterone levels in males can lead to erectile dysfunction. They can also affect sleep, mood, the size of the testicles, and more. In both males and females, low testosterone can lead to lower bone mass and reduced sex drive.

Testosterone is a sex hormone often associated with males, though females have small amounts.

It has many important functions, including:

  • the development of the bones and muscles
  • the deepening of the voice, hair growth, and other factors related to appearance
  • the production of sperm

Testosterone production can slow as a person ages, and many older people experience symptoms of low testosterone.

The American Urological Association defines low testosterone as less than 300 nanograms (ng) of the hormone per deciliter (dl) of blood. They also report that about 2 in every 100 men have low testosterone.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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Below are common signs and symptoms of low testosterone.

Reduced muscle mass

Testosterone plays a role in the development of muscle mass, and reduced levels of the hormone can result in a significant loss of muscle mass.

However, as low testosterone causes a decrease in mass, the function and strength of the muscles do not diminish, according to a 2016 review.

Reduced bone mass

Testosterone helps to produce bone tissue and maintain bone volume. Low testosterone can lead to a reduction in this volume, which can make the bones more susceptible to fractures.

Reduced sex drive

People with low testosterone often experience a reduction in sex drive.

A diminishing sex drive occurs naturally with age, but when the cause is low testosterone, a male will notice a significant decrease in the desire for sex.

A decrease in energy levels

Low testosterone can lead to reduced levels of energy and fatigue.

A person may feel tired, even after adequate rest, or develop a diminished interest in exercise or movement.

An increase in body fat

A reduction in testosterone can lead to an increase in body fat.

In some cases, people with a deficiency of the hormone develop gynecomastia, which causes an enlargement of the breasts.

Hair loss

Many people experience hair loss as a natural part of aging, and age-related hair loss can also affect anyone.

Authors of an older study from 2012 found that testosterone implants supported hair regrowth in some women receiving treatment for symptoms of sex hormone deficiency.

Males may experience specific symptoms of low testosterone levels.

Problems with erections

Low testosterone can make it difficult to achieve or maintain erections. However, low testosterone itself is not always a direct cause of erectile dysfunction. People with high testosterone levels can find it difficult to achieve erections, and people with low levels the opposite.

Testosterone stimulates the penile tissues to produce nitric oxide, which starts several reactions that result in an erection. If levels of the hormone are too low, a man may not be able to get an erection.

Other factors that can cause erectile dysfunction include:

Studies show that testosterone replacement therapy can improve erectile function in people with mild erectile dysfunction.

Reduction in testicle size

A male with low testosterone may notice a reduction in the size of their testicles that is not related to cold temperatures.

Reduction in the amount of semen

Semen is the fluid that makes up the majority of male ejaculate. This type of fluid helps the sperm move toward the egg.

Testosterone helps stimulate the production of semen, and reduced semen levels can indicate a reduction in testosterone. It can also lead to fertility issues.

Difficulty sleeping

People with low testosterone may find it difficult to fall or stay asleep.

Low testosterone levels are common in men who have sleep apnea. This potentially severe disorder causes a person to temporarily stop breathing, which can disrupt sleep.

Changes in mood or mood swings

Some evidence suggests that people with low testosterone levels are likely to experience a lack of focus, irritability, and depression.

One 2017 review found that testosterone replacement therapy significantly improved depression symptoms and overall quality of life in those with low testosterone.

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Females may also experience specific low testosterone symptoms, such as the following.

Irregular menstrual cycles

Low testosterone levels can cause a hormonal imbalance that results in an irregular menstrual cycle.


Testosterone helps the body produce healthy red blood cells (RBCs). Low testosterone levels could lead to anemia, a blood disorder that may occur due to the decrease of RBCs. The main symptom is fatigue.

An older 2006 study found that women over 65 with low testosterone levels tended to have lower hemoglobin levels, putting them at greater risk for anemia.

Testosterone production generally begins to decrease after the age of 30 and after menopause. However, younger people may also have low testosterone levels.

In males, hypogonadism, a condition where the testicles produce little or no testosterone, may occur at any age.

Conditions that may cause hypogonadism include:

In females, low testosterone levels may result from conditions, such as:

Low testosterone does not always present symptoms, and some people only learn about it after a routine physical examination with blood work.

However, anyone who experiences one or more of the above symptoms should seek medical attention.

To diagnose low testosterone, a doctor will often perform a physical evaluation and review the person’s symptoms. The doctor may also request testing to look for additional signs.

For example, a bone density test can show diminished bone mass, one result of low testosterone.

The most common treatment is testosterone replacement therapy (TRT).

A doctor will typically only prescribe TRT if the person has several symptoms of low testosterone and blood test results that indicate a deficiency.

There are several delivery methods of TRT, including:

  • skin patches
  • gels
  • tablets that dissolve in the mouth
  • injections
  • surgically implanted pellets that release the hormone

Most people will notice relief from symptoms within 3–60 weeks of starting TRT. This can vary depending on the symptom.

Weight loss and exercise can often increase testosterone levels naturally.

While changes to the lifestyle and diet alone may not raise levels sufficiently, they can often help.

It is important to remember that males typically lose testosterone as they age, and the potential benefits of lifestyle changes also decrease over time.

Diets high in trans-fats can negatively impact a person’s testosterone levels, while zinc, omega-3 fatty acids, and antioxidant vitamins can support testosterone production.

Eating a balanced diet rich in nutrient-dense whole foods and low in trans-fats may help boost a person’s testosterone levels.

Learn more about natural ways to boost testosterone here.

Below are some commonly asked questions about low testosterone.

What happens when a male’s testosterone is low?

When a male’s testosterone levels are low, it can cause a variety of symptoms. These can include low libido, erectile dysfunction, depression, irritability, and reduced lean muscle mass.

It can also cause a reduction in testicle size, lower amounts of semen, and difficulty sleeping.

If a person notices these symptoms, they should speak with a doctor. A doctor can then come up with a treatment plan to increase their testosterone levels. Treatment often includes testosterone therapy.

Can low testosterone cause diabetes?

Studies show that low testosterone levels in males have an association with type 2 diabetes, the most common form of diabetes.

Testosterone helps the body’s cells increase glucose, or blood sugar, in response to insulin, a hormone that regulates glucose. Reduced testosterone can affect insulin resistance. This can cause the body to produce more insulin to keep glucose levels normal.

When the cells are full of glucose, the body stores the excess in fat cells, which may lead to conditions such as type 2 diabetes and obesity.

Does a person consult a urologist or endocrinologist for low testosterone?

A primary care physician may refer an individual to a urologist, who specializes in diseases of the male reproductive system, or to an endocrinologist who specializes in hormone-related diseases.

Does low testosterone affect fertility?

About 15% of men with fertility problems have low testosterone levels.

However, low testosterone does not cause infertility. In people with fertility problems, low testosterone may be a symptom of a testicular function issue causing infertility rather than a cause of infertility itself.

For example, testicular atrophy can cause infertility and also reduce a person’s testosterone levels. In this instance, the low testosterone levels are a symptom of an underlying condition, not a cause of infertility.

Is low testosterone genetic?

Genetic variants that affect the Y chromosome and the sex hormone-binding globulin may result in a higher risk for low testosterone. SHBG is a protein that helps deliver testosterone to the body’s tissues.

Rare genetic disorders such as Klinefelter syndrome, where males have an extra X chromosome, may also affect testosterone production.

A 2021 study identified 141 new genetic markers that may assist in determining the risk for low testosterone.

The American Urology Association reports that low testosterone affects around 2 in every 100 men. The risk increases with age, though most people naturally lose testosterone as they get older.

Most cases of low testosterone are treatable, and being aware of the symptoms can help a person receive an early diagnosis and treatment.

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