Testosterone plays a vital role in various bodily functions, including muscle and bone health, cognition, red blood cell and sperm formation, and sexual and reproductive function in males.

Testosterone levels can decline for various reasons, including stress, aging, trauma, and infections.

This article discusses TRT in more detail, including who it is for, the types, how it works, how to get it, what to expect from it, and more.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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TRT, or androgen replacement therapy (ART), is a treatment that doctors give to males with testosterone deficiency who show symptoms of hypogonadism.

Taking prescription testosterone helps restore the levels of this hormone in the blood, reversing the symptoms of low testosterone. People who take it may notice improvements in alertness, sexual function, energy, mood, and overall well-being.

Who is testosterone replacement therapy for, and how does it work?

Doctors prescribe TRT to males with hypogonadism. To receive a definitive diagnosis, blood tests must show that a person has low testosterone levels, which the American Urological Association notes as being below 300 nanograms per deciliter (ng/dl). The individual must also have other symptoms, such as fatigue, breast growth, and sexual dysfunction.

However, doctors do not usually recommend TRT as the first course of action for low testosterone levels, even for males who show such symptoms.

If other conditions or medications cause testosterone levels to drop, doctors usually treat the underlying condition before recommending TRT.

According to a 2019 study, TRT can improve sexual function, including:

  • libido
  • symptoms of erectile dysfunction
  • sexual satisfaction

Further 2019 research suggests that TRT can also maintain bone density, with a 2022 study also revealing that TRTs may improve cognitive function and attention span.

However, these benefits were quite modest and went away with the discontinuation of TRT. Around half of the participants in the 2019 study still had bone mineral density in the ranges of osteopenia or osteoporosis while on TRT.

TRT is only available with a prescription. If a person presents with symptoms consistent with low testosterone levels, a doctor will only provide a prescription after taking a thorough medical history and performing physical and lab exams.

As hormone levels fluctuate depending on activity levels, diet, and the time of day, doctors usually take two different blood samples before noon. They may sometimes also ask for imaging studies and additional tests, such as tests for luteinizing hormone and follicle stimulation hormone, to determine the cause of the low testosterone levels.

There are several ways to administer testosterone:


Injectable testosterone is an inexpensive and common form of TRT. A person can receive short-acting treatment, which involves a shot every 1 or 2 weeks, or long-acting treatment, in which the second shot is 4 weeks after the first, and all others are 10 weeks apart. The dosage and frequency of the treatment may vary depending on the person.

Doctors inject short-acting testosterone under the skin or into the muscle, while long-acting shots go in the gluteal muscles.

TRT can cause fluctuations in testosterone levels, which can affect energy levels, libido, mood, and the presence of symptoms such as breast tenderness.

Topical (transdermal)

People usually apply gels and creams on a daily basis. Gradual absorption causes more stable testosterone levels in the blood.

However, people using topical treatments must be careful to avoid skin-on-skin contact with other people for at least 6 hours after application. It is important to prevent the risk of transferring the medication onto other people’s skin because it may be dangerous for pregnant people and children.

Topical patches stick to the skin and stay in place for 24 hours until the next dose. They typically come in doses of between 2 milligrams (mg) and 5 mg. The downsides to patches are that they are not cosmetically appealing and often cause skin irritations. In comparison with oral medications, topical patches may prove less toxic to the liver.

Topical gel dosage is usually between 40–100 mg per day but this will vary between products. A person should start at the lowest recommended dose and increase gradually, if necessary.

Cheek or buccal patches

A person places a buccal patch above the upper teeth, and it releases testosterone over 12 hours. These patches usually contain 30 mg. A person should apply them twice each day, around 12 hours apart. However, they can cause headaches and gum and mouth irritation.

Testosterone implants or pellets

Testosterone pellets are small plastic pellets that doctors implant under the skin. The implant goes into a person’s upper hip or buttock. The pellets dissolve slowly and can deliver TRT for 3–6 months. The dosage varies between individuals and a person should discuss this with their doctor prior to the first implantation.

Inserting implants is a minor inpatient surgical procedure. A doctor makes a small incision in the fatty tissue below the skin to insert the pellets. They perform the procedure under local anesthesia.

Learn more about testosterone pellets here.

Oral testosterone

Oral testosterone is a less common type of TRT that is more expensive and less practical. Its long-term use can potentially cause liver damage.

Most tablets also come with warnings about the drug causing hypertension and stroke. As a result, only individuals who cannot use other forms of TRT resort to taking testosterone by mouth.

A doctor will recommend a dosage ranging from 225–396 mg, and a person will typically take oral testosterone tablets twice daily.


A person applies nasal testosterone gel to the inside of the nose. They will need to do this three times a day at intervals of 6–8 hours, preferably at the same times every day. The dosage is usually 11 mg per application across both nostrils, resulting in a total dosage of 33 mg daily.

Some common reactions to this treatment include headaches, nosebleeds, a runny nose, and nasal discomfort.

TRT aims to restore a person’s testosterone levels to normal. The individual can expect improvements in their blood testosterone levels within a week, however, symptoms may take longer to improve.

A person may also note other benefits, such as an increase in bone density and lean body mass, an improvement in well-being, and a boost to energy and libido. It may take from 4 weeks to several months to see positive changes.

Unless caused by medical illness, TRT is typically a lifelong treatment. Once a person starts TRT, their doctor will continually monitor their response to treatment. People need to have routine checkups at least every 6–12 months to assess their blood testosterone levels.

A doctor will also monitor changes in symptoms and side effects at 3 and 6 months after the initial treatment and then annually.

TRT costs range from $1,650 to $3,200 per year depending on various factors, including:

  • type of medication
  • dosage
  • mode of administration
  • insurance coverage
  • doctor and laboratory fees

In addition to the possible short-term side effects, TRT may also cause health risks. The Endocrine Society recommends that people with the following conditions do not start using TRT:

It also states that the treatment is unsuitable for males who wish to conceive in the near future.

Males aged 40 years older, preadolescent people, and those with migraine or epilepsy may require special considerations.

The Endocrine Society recommends that people with the following conditions do not start taking TRT:

Obstructive sleep apnoea

Research recommends that clinicians need to exercise caution when prescribing TRT to people who have severe obstructive sleep apnoea.

TRT causes neuromuscular changes to the airways as well as chemical changes in the metabolism. It can also cause low levels of oxygen in the body tissues, known as hypoxia. This can cause symptoms such as confusion, restlessness, difficulty breathing, rapid heart rate, and bluish skin.

TRT may also cause hypercapnia. Hypercapnia is a condition where carbon dioxide levels get too high in the blood. This can lead to problems such as respiratory acidosis, with symptoms including fatigue and drowsiness or a strong desire to sleep.

Severe lower urinary tract symptoms

Severe lower urinary tract symptoms include urinary frequency and urgency. These symptoms may be a sign of an enlarged prostate or benign prostatic hyperplasia (BPH).

Past research found a correlation between TRT and lower urinary tract symptoms (LUTS) due to testosterone’s growth-promoting effects on the prostate. This is common among aging men who developed hypogonadism late in their life. Recent clinical trials support this theory, concluding that although TRT may help in reducing prostate inflammation, it does not lower urinary tract symptoms and may even make these symptoms worse in the long term.

Elevated hematocrit levels and thrombophilia

People who have a high red blood cell count and thrombophilia should avoid taking TRT. TRT can increase red blood cell count which in turn increases blood viscosity. This may lead to blood clot formation, stroke, and ischemia.

A 2021 research study conducted on trans men using long-term TRT concluded that TRT caused an increase in red blood cell count. Red blood cell counts were taken from the individuals on a yearly basis and results showed an increase of 10% after the first year and 38% after 10 years.

Prostate cancer

Prostate cancer needs testosterone to grow, therefore taking TRT may make the cancer cells grow faster. The National Cancer Research Institute states that men with higher levels of testosterone in their blood are more likely to be diagnosed with prostate cancer.

High prostate-specific antigen levels

Research has shown a link between TRT raising antigen levels in men over the age of 65 years. Researchers performed a clinical trial on men aged over 65 who took TRT for a period of 12 months. At the end of the 12 months results showed an increase of 4.0 ng/mL in antigen levels in 5% of the men.

Ischemic stroke

Researchers carried out clinical trials on 15,401 men aged over 45 years who had low testosterone levels. Those who were given TRT showed a 21% greater risk of cardiovascular conditions such as cardiac arrest and cerebrovascular disease compared to the proportion of men who did not take TRT.

The Food and Drug Administration (FDA) explains that the benefits and safety of TRT for treating low testosterone levels due to aging are not known. The organization requires that testosterone products carry warnings mentioning the possible risk of stroke and heart disease.

A 2019 review found that males undergoing TRT may have a higher risk for cardiovascular events such as stroke. However, further research will help to confirm this.

Other side effects of taking testosterone include:

High cholesterol may also be a side effect. However, a 2021 study suggests that TRT may improve total cholesterol levels.

The current scientific literature suggests that TRT worsens breast and prostate cancer. However, TRT may offer benefits to people with early-stage prostate cancer without stimulating the recurrence or progression of cancer.

A person can try to improve their testosterone levels without medical intervention. Some ways may include:

  • getting enough sleep
  • eating a balanced diet
  • losing weight
  • getting enough exercise
  • reducing stress
  • taking vitamins and minerals, such as vitamin D and magnesium
  • avoiding drugs and alcohol

If any individual takes medications they believe lowers testosterone, they should consider discussing this with their doctor.

Find out more about natural ways to boost testosterone here.

The following are common questions about TRT.

How much does TRT cost?

TRT costs range from $1,650 to $3,200 per year, depending on the type of TRT, the mode and frequency of administration, and a person’s insurance coverage.

Does insurance cover TRT?

Yes. Most insurance companies cover all forms of TRT. However, there may be out-of-pocket costs. Individuals should always confirm coverage with their insurer to avoid any unwanted expenses.

Is testosterone replacement therapy safe?

Although TRT offers benefits to people with low testosterone levels, it can cause many short-term side effects.

A 2021 study suggests that long-term TRT improves liver function and reduces cardiovascular risks. However, further studies are needed to assess the long-term effects.

A study is currently underway which is assessing the long-term cardiovascular outcomes for persons on TRT.

How long should I stay on testosterone replacement therapy?

TRT treatment length is indefinite unless the low levels are due to an underlying cause that is treatable.

What does TRT do to your body?

Some physical changes that TRT can bring about include increased muscle mass and bone density, and decreased body weight.

Is TRT covered by insurance?

If a person has TRT as a treatment for a health condition, their medical insurance should cover this cost.

How do I take testosterone therapy?

People can take TRT orally, via intramuscular injections and implants or transdermal patches, mouth patches, and topical creams or gels. Other options include intranasal gels or pellets.

Some options require daily administration, others weekly or monthly and some every three months.

Options available depend on the person’s medical needs and lifestyle/ People should discuss these with their healthcare practitioner prior to commencing treatment.

How will doctors monitor my TRT?

Doctors monitor TRT treatment through blood tests, physical examinations, and scans.

The blood tests measure total serum testosterone, complete blood count (hematocrit), and prostate-specific antigens (PSA). People can expect to have these blood tests at the start of the treatment, then three to six months later. Doctors will then repeat these tests annually if the results prove to be stable.

Individuals with osteoporosis or low trauma fracture history will undergo a bone density scan one to two years after the initiation of TRT therapy.

TRT is a common treatment for low testosterone levels, but it may not suit everyone.

People who are considering TRT need a prescription and appropriate guidance from a doctor or qualified healthcare professional.