Testosterone Replacement Therapy (TRT)

What is testosterone replacement therapy (TRT)?

Testosterone replacement therapy (TRT) is an option for people assigned male at birth (AMAB) who have low testosterone levels due to male hypogonadism. TRT involves taking manufactured forms of testosterone to regulate your levels of this hormone.

TRT comes with certain risks and benefits. Together, you and your healthcare provider will decide if TRT is right for you.

Who is TRT for?

The U.S. Food and Drug Administration (FDA) approves testosterone replacement therapy for people AMAB who have low testosterone levels due to a known medical condition (hypogonadism).

Hypogonadism can develop from damage to or malfunction of one of the following organs that are part of testosterone production:

• Testicles
• Pituitary gland
• Hypothalamus

For example, chemotherapy or radiation therapy can damage one of these organs. Or you may have a genetic condition that causes issues.

The FDA doesn’t approve the use of TRT for people AMAB with low testosterone without an associated medical condition. As of 2025, it’s not yet approved for people AMAB who naturally experience a decline in testosterone as they age.

TRT isn’t for everyone. Certain existing health conditions make it unsafe, like prostate cancer and heart failure.

What happens before starting TRT?

Before starting TRT, your healthcare provider will make sure low testosterone is an accurate diagnosis. They’ll also make sure TRT is safe for you. They’ll ask about your medical history and do a physical exam. They may order the following blood tests:

• Two morning testosterone tests (for diagnosis)
• Hemoglobin
• Hematocrit
• Liver function tests
• Luteinizing hormone blood test
• PSA (prostate-specific antigen) test
• Prolactin blood test

How does TRT work?

With TRT, you take a manufactured form of testosterone to regulate your levels. This can help improve the symptoms of low testosterone, like low libido and lack of energy.

TRT doesn’t fix or cure the underlying cause of low testosterone. In fact, it will cause your testicles to stop working. This means that you’ll need the medication to continue having a normal level of testosterone in your body. If you stop taking testosterone, your body will have to recover its ability to make testosterone again.

Testosterone replacement therapy has several different forms, including:

• Testosterone skin gels. You apply the gel every day to clean, dry skin as directed. It’s important that you don’t transfer the gel to another person through skin-to-skin contact while the gel is wet. Testosterone skin gels are one of the most common forms of TRT in the U.S.
• Intramuscular testosterone injections. You give the injections into a muscle every one to two weeks. Some formulations of long-acting testosterone can be given by injection every 10 weeks. But you have to get them in a medical office.
• Subcutaneous testosterone injections. You give the injections under your skin every week.
• Testosterone patches. You apply these patches every day to your skin as directed. You usually have to switch up their location to avoid skin reactions.
• Testosterone pellets. A provider implants these pellets under your skin every three to six months. The pellets provide consistent and long-term testosterone dosages.
• Buccal testosterone tablets. These are sticky pills that you apply to your gums twice a day. The testosterone absorbs quickly into your bloodstream through your gums.
• Testosterone nasal gel. You apply a testosterone gel into each nostril three times a day.
• Oral testosterone. This is a pill you take twice a day.

Your healthcare provider will work with you to figure out which option is best for you. After you start TRT, you’ll need follow-up testing. This includes monitoring your testosterone level and getting other blood tests to make sure TRT isn’t harming your health.

What are the benefits of TRT?

Testosterone replacement therapy can improve many of the symptoms of low testosterone (male hypogonadism). TRT may improve your:

• Sexual function
• Lean body mass
• Bone mineral density
• Mood
• Energy levels
• Sense of well-being

But it’s important to remember that TRT comes with potential risks and side effects.

What are the side effects of TRT?

The side effects of testosterone replacement therapy include:

• Acne or oily skin
• Swelling in your ankles caused by mild fluid retention
• Stimulation of your prostate, which can cause urinary symptoms
• Breast enlargement (gynecomastia) or tenderness
• Worsening of sleep apnea
• Smaller testicles
• Skin irritation (if you use topical testosterone replacement)
• Decrease in sperm count, leading to infertility

Laboratory abnormalities that can happen while on TRT include:

• Increase in prostate-specific antigen (PSA) level
• Increase in red blood cell count, which thickens your blood

How long does it take to see results from TRT?

It may take a few weeks before you start noticing differences in your body and mood once starting TRT. How long it takes varies from person to person. To allow the therapy to take full effect, healthcare providers typically wait 30 days after you start TRT to check your testosterone levels.

If you don’t notice an improvement in your symptoms after taking TRT for three to six months, your provider may recommend stopping the therapy. This is because if your symptoms don’t improve, your testosterone level may not be the cause of your symptom.

How long can you stay on testosterone replacement therapy?

You can stay on testosterone replacement therapy for as long as it’s benefiting your symptoms and not causing health issues. TRT is meant to be a long-term therapy. If you stop taking testosterone, your levels will return to baseline.

Your healthcare provider will recommend regular testing to make sure TRT isn’t hurting your health.

Once you start TRT, can you stop?

Yes, you can stop TRT once you’ve started. You may do this for several reasons, like if:

• You have bothersome side effects
• The therapy isn’t improving your symptoms
• You develop a health condition that makes TRT unsafe

If you stop TRT, you’ll return to your normal level of testosterone. Your body will take some time to restart production of testosterone naturally.

When should I see my healthcare provider about TRT?

Once you start TRT, you’ll have regular appointments with your healthcare provider and routine blood tests. Your provider will let you know how often you need to do this.

Otherwise, see your healthcare provider if:

• You don’t notice an improvement in your symptoms
• The side effects of TRT are causing you distress
• You want to try a different form of testosterone
• You’re thinking of stopping TRT
• You develop a health condition that could make TRT unsafe

Who shouldn’t use TRT?

TRT can be dangerous for some people because it can make certain health conditions worse. You shouldn’t use TRT if you have:

• Untreated heart failure
• Untreated obstructive sleep apnea
• Had a heart attack or stroke within the past six months
• A history of elevated red blood cell counts
• Untreated prostate cancer
• An unevaluated lump on your prostate
• Male breast cancer

You should also avoid TRT if you’re planning to have biological children. TRT can decrease sperm count and cause fertility issues. Trying to repair your fertility after TRT can be very expensive and take a long time.

TRT is meant for medical purposes. It’s not worth the potential health risks to use testosterone for nonmedical reasons, like bodybuilding or attempting to prevent aging changes.

Is TRT safe?

Certain existing health conditions make TRT unsafe, like prostate cancer, breast cancer and heart failure. This is why healthcare providers do extensive evaluations and tests before approving the use of TRT. If you don’t have these health concerns, TRT is generally safe.

But there aren’t many studies on the long-term effects of TRT (for example, over decades). And some of the studies have mixed results.

For example, some studies suggest that TRT decreases your risk of heart attack over time, while others say it increases your risk. In 2015, the FDA warned that testosterone use is possibly associated with increased cardiovascular risk based on the results of two studies. However, in 2024 the results of a large, randomized trial found that testosterone gel wasn’t associated with increased heart risks over a medium-length period of time. Research has also studied the increased risk of venous thromboembolism, and the results are mixed.

For all these reasons, your healthcare provider will carefully consider if TRT is safe for you based on your unique characteristics.