Low testosterone in men: symptoms, blood test and treatment options

Testosterone is the hormone made mostly by the testicles. It supports sex drive, erections, muscle mass, bone strength and red blood cell production. According to MedlinePlus, levels fall gradually with age.

Low testosterone (doctors call it hypogonadism or testosterone deficiency) is not diagnosed from a single number. The American Urological Association (AUA) and Endocrine Society guidelines require both:

• Symptoms or signs of low testosterone.
• Consistently low levels: two total testosterone measurements, on separate days, early in the morning. The Endocrine Society recommends fasting samples.

The AUA uses a total testosterone below 300 ng/dL as a reasonable cut-off. Normal testosterone levels vary by lab: the reference range is printed on your report.

According to MedlinePlus and the AUA, the most common symptoms of low testosterone in men are:

These symptoms are nonspecific. Fatigue, low mood and erection problems also come from poor sleep, depression, diabetes, thyroid problems, anemia, high blood pressure or medication side effects. That is why the doctor does not guess: she asks, looks at what can be seen on video and confirms with labs. In a video visit, the doctor reviews your symptoms and, if needed, gives you the order for those tests at a lab near you. If fatigue bothers you most, also read fatigue and tiredness. If it is erections, see erectile dysfunction.

According to the Endocrine Society and MedlinePlus, the most common causes are:

The testosterone test is a blood test. According to MedlinePlus, it is drawn in the morning, roughly between 7 and 10, when levels are highest. An afternoon sample can read falsely low.

In a video visit, the doctor reviews your symptoms, medicines and history, and, if needed, gives you a lab order for a lab near you. Per the AUA guideline, the usual workup is:

• Morning total testosterone, twice, on separate days.
• If it is low: LH (luteinizing hormone), which helps tell whether the problem is in the testicles or the pituitary; and prolactin if LH is low or low-normal.
• CBC with hematocrit, because testosterone raises red blood cells.
• PSA in men over 40 before any treatment, per the AUA.
• Other tests, such as glucose, thyroid or FSH, when the doctor orders them.

To understand your report, read how to read lab results.

First, the cause. The AUA guideline says weight loss and lifestyle changes can raise testosterone. Good sleep (and treating sleep apnea), exercise, diabetes control, less alcohol and a review of medicines such as opioids can improve levels without hormones.

Testosterone replacement therapy (TRT). When deficiency is confirmed and you have symptoms, TRT is an option a physician weighs case by case. Forms include skin gels and solutions, patches, injections, pellets placed under the skin, nasal forms and oral capsules. Each has its own use, side effects and monitoring.

TRT affects fertility. Testosterone from outside tells the body to stop making its own, which lowers sperm production. The AUA says it should not be given to men who are trying to conceive.

According to the Endocrine Society, testosterone therapy is not recommended for men who:

High red blood cells. Testosterone raises hematocrit; if it climbs too high, the blood thickens. That is why it is checked before and during treatment.

Blood pressure. In February 2025, the FDA required a warning about increased blood pressure on all testosterone products, after studies confirmed that all of them can raise it.

Heart. The TRAVERSE trial (New England Journal of Medicine, 2023) followed 5,246 men aged 45 to 80 with low testosterone and heart disease or high cardiovascular risk. Major cardiovascular events were similar with testosterone gel (7.0%) and placebo (7.3%). There was more atrial fibrillation, acute kidney injury and pulmonary embolism in the testosterone group. After those results, the FDA removed the cardiovascular-risk language from the boxed warning, but kept the limitation that these products are not approved for low testosterone due to age alone.

Prostate. PSA is monitored in men over 40.

Other effects: acne, breast growth, worsening sleep apnea and, with gels, the risk of passing the hormone to children or women through skin contact.

In the United States and Puerto Rico, testosterone and other anabolic steroids are Schedule III controlled substances under the DEA. They require a valid prescription after a medical evaluation. Buying them without one, online or on the street, is illegal and risky: according to the DEA, most illegally sold steroids come from abroad, and some products have never been tested for safety.

Women make testosterone too, in smaller amounts. According to MedlinePlus, high testosterone in women can be caused by polycystic ovary syndrome (PCOS), among other causes: facial or body hair, acne, hair thinning and irregular periods. The doctor can order hormone tests and evaluate you.

If you use testosterone and have any of these signs, call 911 or go to the emergency room. See when to go to the ER.