Low Testosterone: Symptoms, Causes, and Myths
Learn the facts about low testosterone: normal age-related changes, real symptoms, causes, how it is diagnosed, and the benefits and risks of testosterone therapy.
Key takeaways
- Testosterone gradually declines with age, but true low testosterone (hypogonadism) requires both symptoms and consistently low blood levels.
- The American Urological Association uses a total testosterone level below 300 ng/dL as a reasonable cutoff for diagnosis.
- Obesity, type 2 diabetes, sleep apnea, certain medications, and opioid use can contribute to low testosterone.
- Testosterone therapy has benefits and risks and should only be used under medical supervision.
Ads for "low T" treatments are everywhere, promising more energy, muscle, and vitality. But testosterone is often misunderstood. Some men who could benefit from treatment go undiagnosed, while others take testosterone they don't need.
Here's what you should know.
What is testosterone?
Testosterone is the main male sex hormone, produced mostly in the testicles. It plays a role in:
- Sex drive and erectile function
- Sperm production
- Muscle mass and strength
- Bone density
- Fat distribution
- Red blood cell production
- Mood and energy
Does testosterone decline with age?
Yes, gradually. Testosterone levels typically decline by about 1% per year after age 30 to 40. Many men maintain levels within the normal range throughout life, however, and the slow age-related decline alone doesn't usually cause significant symptoms.
What is low testosterone (hypogonadism)?
Testosterone deficiency, or hypogonadism, is diagnosed when a man has both:
- Symptoms consistent with low testosterone, and
- Consistently low blood testosterone levels, measured on at least two separate mornings
The American Urological Association considers a total testosterone level below 300 ng/dL a reasonable cutoff to support a diagnosis.
Symptoms
- Low sex drive
- Erectile dysfunction
- Reduced morning erections
- Fatigue and low energy
- Loss of muscle mass and strength
- Increased body fat
- Depressed mood or irritability
- Trouble concentrating
- Decreased body and facial hair
- Hot flashes
- Low bone density or fractures
- Infertility
Many of these symptoms are not specific to low testosterone. Fatigue, low libido, and low mood can also be caused by depression, poor sleep, thyroid problems, medication side effects, or other conditions. That's why proper testing matters.
Causes of low testosterone
- Obesity, one of the most common contributors
- Type 2 diabetes
- Sleep apnea and poor sleep
- Certain medications, including opioids and long-term steroids
- Anabolic steroid use (which can suppress natural production)
- Heavy alcohol use
- Injury, infection, or cancer treatment affecting the testicles
- Pituitary gland problems
- Genetic conditions, such as Klinefelter syndrome
- Chronic illnesses, such as kidney or liver disease, and HIV
How it's diagnosed
Your doctor will ask about symptoms, review your medical history and medications, and do a physical exam. Blood tests should be taken in the early morning, when testosterone levels are highest, and repeated to confirm. Additional tests may check pituitary hormones (LH and FSH), prolactin, red blood cell count, and other factors.
Treatment options
Address underlying causes first
Many men can improve testosterone levels by:
- Losing excess weight
- Treating sleep apnea and improving sleep
- Exercising regularly, especially strength training
- Limiting alcohol
- Reviewing medications with a doctor
Testosterone therapy
For men with confirmed hypogonadism, testosterone therapy is available as gels, injections, patches, pellets, and oral forms. It may improve sex drive, energy, mood, muscle mass, and bone density.
Potential risks and side effects include:
- Increased red blood cell count, which may raise clot risk
- Acne or oily skin
- Breast enlargement or tenderness
- Worsening of untreated sleep apnea
- Reduced sperm production and infertility; testosterone therapy is generally not appropriate for men who want to father children in the near future
- Fluid retention
Men on testosterone therapy need regular monitoring of testosterone levels, red blood cells, and, depending on age, PSA.
Avoid buying testosterone or "testosterone boosters" online without a prescription. Supplements marketed to boost testosterone are not FDA-approved for that purpose, may not work, and can contain hidden or harmful ingredients.
Common myths
| Myth | Fact |
|---|---|
| Every older man needs testosterone. | Most older men don't have true hypogonadism. Treatment is for men with symptoms and confirmed low levels. |
| Testosterone therapy will make you young again. | It can relieve symptoms of deficiency but isn't an anti-aging cure. |
| Over-the-counter boosters raise testosterone. | Most lack solid evidence. |
| Low T is just about sex. | Testosterone affects bone, muscle, mood, energy, and red blood cells. |
When to see a doctor
Talk to your doctor if you have persistent symptoms like low sex drive, erectile dysfunction, fatigue, or loss of muscle mass. A primary care doctor, urologist, or endocrinologist can help determine the cause.
The bottom line
Low testosterone is a real medical condition, but it's not as common as marketing suggests. If you have symptoms, get properly tested, address lifestyle factors, and make treatment decisions with your doctor.
Last reviewed and updated: July 6, 2026
This article is for general information only. It isn't medical advice and can't replace a visit with your doctor, pharmacist, or other licensed health professional who knows your history. Read our full medical disclaimer.
