Feeling lethargic with low energy not only in the bedroom but also at work and at play? The problem could be low levels of testosterone, the male sex hormone responsible for muscle and bone strength, sex drive and overall wellness. Depending on your blood test results, the best testosterone booster for you may be one of the many forms of testosterone replacement therapy (TRT).
To find out if you might be a candidate for these prescription products, Bottom Line Personal asked researcher and endocrinologist Reina Villareal, MD, from Baylor College of Medicine.
Identifying Low Testosterone
After peaking in his teens, a man’s testosterone level naturally declines by about 1% a year after age 30. Other factors can accelerate this decline, with obesity topping the list.
But there is a lot you can do on your own to help boost your testosterone levels, starting with weight loss. For the details on that and other natural testosterone boosters, go to “How to Increase Testosterone Naturally.” If these steps don’t give you the renewed energy and sex drive you’re hoping for, it might be time to consider TRT.
What Is TRT?
TRT, which involves manufactured forms of testosterone, is available in a variety of forms. Synthetic testosterone is manufactured in the same way that testosterone is produced in the body. In the human body, the process starts with the molecule cholesterol undergoing several biochemical transformations prior to the production of the final product—testosterone. In the laboratory, the same thing happens only the manufacturers use phytosterol, which comes from plants (mostly soy), to synthesize testosterone.
The best product for you depends on your personal preference, overall health and the medications you’re taking as well as your insurance coverage—insurance companies and Medicare typically cover the cost of only some forms of TRT.
Testosterone injections are effective for increasing and maintaining levels of testosterone. These usually are covered by insurance. Possible side effect: Mild pain at the injection site.
Transdermal patches and gels are applied to the skin, so they are convenient. These usually are covered by insurance. Transdermal testosterone gel is the most commonly prescribed testosterone preparation. Caveat: You’ll need to prevent other people from coming into contact with the product. For the gel, you’ll wait for it to dry, then cover your arm with a shirt. The patch has to be removed prior to any MRI procedure because it contains metal and may result in skin burns if left on. Possible side effect: Skin irritation at the application site.
Pellets are implanted under the skin and offer stable testosterone levels for up to six months. Since implantation requires minor surgery typically every three months, pellets typically are more expensive and are not always covered by insurance. Possible side effect: An infection sometimes develops at the implant site.
Nasal spray: A testosterone gel is sprayed into each nostril three times a day, making it somewhat inconvenient. It is also associated with nasal discharge, nasal bleeding, inflammation of the nasal passages, sinusitis and scabbing. Some insurers, including Medicare Part D, do not cover this type of testosterone preparation.
Pills are easy to take but may be less effective, and there is some concern about liver damage so they’re among the least commonly prescribed forms of testosterone. While most insurance covers TRT, oral testosterone may not be the first line covered. Patients need to check with their insurers.
Who Is a Candidate for TRT?
Candidates for TRT typically have secondary hypogonadism (commonly called low T), meaning that something has gone wrong with the signaling between the brain’s hypothalamus and pituitary gland and the testicles, which tell the testes to produce testosterone. More men are being diagnosed with low T than in the past—that’s likely because of the obesity epidemic and other factors such as exposure to endocrine-disrupting chemicals. Often thought of as an older man’s condition, we now see low T in men in their 40s and sometimes even younger.
Far less common is primary hypogonadism, which stems from a defect in the testicles themselves, such as undescended or absent testis…from direct trauma or infection… from radiation to the testis…or from drugs such as those used in chemotherapy and even ones used to treat fungal infections. It also can come from a genetic condition, such as Klinefelter syndrome. TRT is also a treatment for primary hypogonadism.
Testing: According to the updated guidelines from the Endocrine Society, the normal testosterone range is quite wide, roughly 300 nanograms per deciliter (ng/dL) to 1,000 ng/dL. The Endocrine Society uses 264 ng/dL as the cutoff, while the American Urological Association uses 300 ng/dL. As a first step, your doctor will confirm low T with a simple blood test. For the most accurate result, the test should be done after fasting because food suppresses testosterone and between 8:00 and 10:00 in the morning—that’s when testosterone levels naturally peak and then gradually decline over the course of the day.
Your doctor likely will prescribe TRT if your testosterone levels are consistently below 264 ng/dL according to the Endocrine Society or below 300 ng/dL according to the American Urological Association and you have certain physical, cognitive and/or emotional symptoms, such as decreased sex drive, erectile dysfunction or other sexual problems…loss of energy, muscle and strength…increased body fat…and/or fatigue, depression, anxiety, irritability and difficulty concentrating. If your first blood test shows low testosterone, the test will be repeated under the same conditions at least a week later. If it’s again low, you and your doctor can discuss TRT.
Based on a study published in 2017 involving more than 9,000 men, the gold standard is the harmonized testosterone test that uses mass spectrometry. “Harmonized” means that reference ranges have been standardized across different laboratories and institutions for more accurate and consistent results. One limitation of this approach: The normal testosterone range the test covers is 264 ng/dL to 916 ng/dL and for “a non-obese population of European and American men, 19 to 39 years.” This leads some to argue that the harmonized testosterone test doesn’t take into account that a normal testosterone level for a man at 39 is not the same as for a man at 79—everyone age 40 and older is measured against the same standard. Example: If your testosterone is 270 ng/dL, essentially your levels are considered “normal” according to the reference range, but you may need a higher level of testosterone for your symptoms of low T to be fully treated.
To rule out primary hypogonadism, your doctor also will check levels of the pituitary hormones luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin. Elevated pituitary hormones are a sign of testicular dysfunction. You will need other tests to find the cause of the dysfunction. With secondary hypogonadism, LH and FSH levels typically are normal or low along with low testosterone.
Monitoring TRT and Its Risks
To see how you’re responding to TRT, your testosterone level will be checked regularly. The testing schedule will depend on the form of TRT you’re taking. Example: If you’re getting injections, your doctor will check your testosterone level midway between your last injection and the next one. (It usually takes three months to see improved energy and sex drive.)
Because testosterone can cause your red blood count to rise too high, increasing risk for blood clots, it will be tested as well. Your level of prostate-specific antigen (PSA), a protein produced by the prostate gland, will be monitored as well because testosterone can worsen an enlarged prostate and the urinary issues that go along with it.
It’s common to experience a cyclical effect when on TRT—you feel great immediately following treatment but start feeling low as you get closer to the next one. For people who go through difficult emotion cycles, the gel is recommended over injections.
For the past 10 years, TRT came with a black box warning about increased risk for heart attack and stroke. But an extensive multicenter research study involving 5,200 participants of varying ages compared the effects of a placebo against testosterone and found no increased risk. In early 2025, the black box was removed by the FDA. (Note: The Endocrine Society still advises that TRT should not be started in anyone within the first six months of a stroke or heart attack.)
Interesting finding: There was an increase in the number of bone fractures from trauma in the testosterone group despite good bone density. That is likely because men on TRT engaged in more high-risk activities due to their newfound energy.
What If You’re Not a Candidate for TRT?
Men who don’t qualify for TRT based on their blood test results may turn to over-the-counter products marketed to boost testosterone. These dietary supplements are not regulated by the FDA, meaning that they are not subjected to rigorous scrutiny for safety and effectiveness so there’s no guarantee regarding quality, purity or potency of the ingredients and, even more importantly, there’s no way to know if any of them are harmful. Some of these products may interact with other medications you’re taking or have other adverse effects. And there is also no way of knowing whether the ingredients listed on the label are actually the ingredients inside the bottle.
If you do want to try such a product: Work with an endocrinologist or a urologist who can look at the ingredients for possible negative interactions with medications you’re taking and monitor you while you’re on it.
