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Low testosterone, also called male hypogonadism, is a medical condition in which the testicles do not produce enough testosterone, the primary male sex hormone. A diagnosis requires both characteristic symptoms and consistently low blood testosterone confirmed on more than one morning blood test—not a single number alone.
Testosterone drives the development of male reproductive tissues and supports sperm production, muscle and bone mass, fat distribution, red blood cell production, sex drive, and mood. Levels peak in early adulthood and gradually decline with age, decreasing by roughly 100 ng/dL per decade after about age 30. A natural age-related dip is not the same as a clinical condition that warrants treatment.
Most laboratories consider a total testosterone of about 300–1,000 ng/dL to be the normal range. The Endocrine Society sets a practical threshold of 264 ng/dL, below which testosterone is considered low when symptoms are also present. Hypogonadism is common: large U.S. screening data (the HIM study) found roughly 35–40% of men over 45 met the criteria, and prevalence rises to about 50% among men with obesity or type 2 diabetes.
Doctors classify low testosterone by where the problem originates.
Common reversible or contributing factors include:
Symptoms vary, and some men have none. The most specific signs relate to sexual function and reproduction:
Because fatigue, low mood, and reduced sex drive have many causes, symptoms alone cannot confirm low testosterone.
Diagnosis requires both consistent symptoms and at least two separate low blood tests. Testosterone follows a daily rhythm and is highest in the morning, so blood should be drawn between 7 and 10 a.m., ideally while fasting. Because levels fluctuate, an abnormal result is repeated before any diagnosis is made.
If both morning total testosterone results are low, a clinician typically orders follow-up tests to find the cause, including:
Treatment starts with addressing reversible causes. Because obesity, poorly controlled diabetes, sleep apnea, and certain medications can lower testosterone, managing these first may raise levels without drug therapy.
Testosterone replacement therapy (TRT) is the main treatment for men with confirmed hypogonadism from a defined medical cause. FDA-approved forms include gels, patches, injections, an oral capsule, implanted pellets, and a nasal gel. In appropriately selected men, TRT can improve libido, energy, mood, muscle mass, and bone density.
TRT also carries risks and is not for everyone. It can reduce sperm production and impair fertility, so men hoping to father children soon may instead consider options such as clomiphene citrate or hCG (used off-label for this purpose). TRT requires ongoing monitoring of testosterone, hematocrit (it can thicken the blood), PSA, and blood pressure. Following the TRAVERSE trial, which found a comparable rate of major adverse cardiac events in the testosterone and placebo groups, the FDA removed the prior cardiovascular Boxed Warning in 2025 but added a blood-pressure warning and kept a caution against use for aging alone. TRT is generally avoided in men with prostate or breast cancer, untreated severe sleep apnea, very high red blood cell counts, or near-term fertility goals.
Healthy habits support hormone balance and overall well-being:
See a healthcare provider if you have persistent symptoms such as low sex drive, erectile dysfunction, unexplained fatigue, loss of muscle or bone strength, or infertility. Seek prompt evaluation for breast enlargement, hot flashes, visual changes, or loss of body hair, which can point to a specific underlying disorder. Only a qualified clinician can confirm low testosterone with proper testing and recommend safe, individualized treatment.
*This article is for general information and education and is not medical advice. Talk with a licensed healthcare professional about your symptoms, testing, and any treatment decisions.*
FDA-approved testosterone replacement therapy (TRT) is available in several forms: transdermal gels and solutions, skin patches, intramuscular or subcutaneous injections (testosterone cypionate, enanthate, or undecanoate), an oral capsule (testosterone undecanoate, e.g., Jatenzo, Tlando, Kyzatrex), surgically implanted pellets (Testopel), and a nasal gel (Natesto). On February 28, 2025, the FDA issued class-wide labeling changes: based on the large TRAVERSE trial (5,204 men with hypogonadism and high cardiovascular risk, in which major adverse cardiac events occurred at a comparable rate of about 7% with testosterone gel and about 7% with placebo), it removed the prior Boxed Warning language about increased cardiovascular risk, added a warning about possible increases in blood pressure, and retained a "Limitation of Use" stating these products are not established as safe or effective for low testosterone due solely to aging. TRT is FDA-approved only for men with hypogonadism caused by a defined medical condition, not for age-related decline alone. All testosterone products are controlled substances and require a prescription; "low-T" clinics, online prescribers, and over-the-counter "testosterone boosters" or supplements are not FDA-evaluated for this use and can be unsafe. Off-label options a clinician may discuss for younger men wishing to preserve fertility include clomiphene citrate and human chorionic gonadotropin (hCG). Any treatment decision should be made with a qualified clinician after proper diagnosis and monitoring. This information is educational and is not a substitute for professional medical advice.
This page is for general information and is not medical advice. Always consult a qualified clinician about diagnosis and treatment. Individual results vary.