What is TRT? Testosterone Replacement Therapy

August 16, 2021

As the primary sex hormone for men, having low levels of testosterone (sometimes called T) can result in an assortment of issues, some of the more common of which include a decrease in sex drive and erectile dysfunction.

But these are far from the only issues that can arise when testosterone is too low, and testosterone replacement therapy (TRT) is commonly used to treat a variety of medical conditions.

Why Does Testosterone Matter? 

Testosterone is the primary male sex hormone for men and plays an important role in several bodily functions, physiological systems, and both fetal development and as we age. 

Some of the most important male health aspects – and traditionally male traits – that testosterone helps to maintain include:

  • Bone density and health
  • Cognitive functions
  • Distribution of fat
  • Facial and body hair
  • Mood
  • Production of red blood cells
  • Production of sperm
  • Sex drive and libido
  • Strength and mass of muscles

How Can You Tell If You Have Low Testosterone? 

As men age, our testosterone levels decline naturally. The overall effects attributed to low testosterone might be difficult to notice; however, some of the most common symptoms of low testosterone include:

  • Concentration problems
  • Depression
  • Difficulty sleeping
  • Erectile dysfunction
  • Fatigue
  • Irritability
  • Less spontaneous erections
  • Loss of facial and body hair
  • Loss of muscle and bone density
  • Low levels of energy
  • Low self esteem or confidence
  • Reduced sex drive
  • Reduced sperm count
  • Unexpected weight gain

If you're experiencing any of these symptoms, talk with a healthcare provider about a testosterone test. This simple blood test will measure the amount of testosterone in your blood, described in nanograms per milliliter (ng/mL), which can be benchmarked against your prior tests and levels expected for most men your age.

Since testosterone levels can fluctuate based on diet, fitness level, medications, and the time of the day that the test is performed, it may require a few tests to get an accurate view. If you've been diagnosed with low testosterone, you might consider asking about testosterone replacement therapy as a potential treatment. 

What Is Testosterone Replacement Therapy? 

Testosterone replacement therapy, also known as androgen replacement therapy, is primarily used to treat men that have low levels of testosterone, either as the result of age, injury, or a medical condition. 

While studies are somewhat mixed regarding the potential risks of TRT, overall the scientific community is supportive that testosterone replacement therapy can greatly enhance the overall quality of life of most patients. 

It’s important to note that while testosterone replacement therapy can help to improve overall levels of testosterone, it is not a permanent cure. Testosterone replacement therapy can be a lifelong treatment in the event that there is no addressable underlying condition for your low testosterone. 

How Is Testosterone Replacement Therapy Administered? 

There are a few factors that go into determining the most effective treatment option and delivery method of testosterone replacement therapy, including the medical need and lifestyle of the patient. Some options have to be administered daily while others might last for a few months. 

These are the most common delivery methods for testosterone replacement therapy:


Testosterone injections are available either deep into the muscles or just underneath the skin. Depending on the exact formula being administered the injection could last for a week or several months. Along with pain and irritation from the needle, this method will feature fluctuations in testosterone levels that can result in similar fluctuations in sex drive, energy levels, and mood. 

Topical Gels and Patches 

This delivery method involves applying the treatment directly to the skin either via a gel or patch. Gels are typically rubbed into the skin once or twice daily, and the patch is usually placed on the upper body or arm once a day. The testosterone is absorbed through the skin in either case.

While these methods are some of the easiest to administer at home, they do come with a few drawbacks. The gel can accidentally be transferred to others that come into contact with it, – by shaking hands after application, for instance – and there may also be an unpleasant odor along with the potential for rash or skin irritation. 

Oral Delivery 

A buccal delivery method is designed to stick to the gums and is typically administered twice daily. The testosterone will be directly absorbed into the bloodstream via the gums. Some people may experience irritation in their gums or mouth. 


Pellets containing testosterone can be implanted underneath the skin around the hips and pelvic area. Over the course of three to six months, these pellets slowly release testosterone. Outside of visiting a healthcare provider in order to get the implantation, there are few side effects associated with this delivery method. 

Nasal Gel 

One of the newer options for testosterone replacement therapy is as a nasal gel. This treatment is designed for the user to apply the gel inside of their nose. One of the benefits of this method is it lowers the risk of accidentally transferring the gel to others as is often the case with other topical treatments. 

However, due to lower concentrations, the gel will need to be applied three times daily in each nostril. Some people report experiencing runny noses or nose bleeds as side effects.  

Oral Tablets

There is another delivery method available in the form of oral tablets, only approved by the FDA in 2019 for the treatment of certain forms of hypogonadism. Because this is a newer form of treatment, many healthcare providers are still unfamiliar with this method.

What Does Testosterone Replacement Therapy Treat? 

Testosterone replacement therapy is used to combat the natural decline of testosterone that is experienced during the aging process as well as clinical medical diagnoses that can lead to low T, like hypogonadism and following certain surgeries. While men of all ages can experience low levels of testosterone, the risk increases dramatically with age. 

Men reach peak testosterone production sometime during their late 20s or early 30s. After this peak, levels drop by roughly 1.6% every year. As a result, roughly 20% of men will have low testosterone levels in their 60s, and nearly half of men will experience it by the time they reach their 80s. 

There are other reasons that someone may seek out testosterone replacement therapy. These conditions include:


This medical condition is when the body fails to produce the required amount of testosterone. There are two distinct types of hypogonadism:

  • Primary: Also known as primary testicular failure, this condition derives from problems that directly involve the testicles. It may occur as the result of an injury to the testicles, various treatments for cancer, or a mumps infection. 
  • Secondary. This is probably the more common of the two and stems from issues relating to the hypothalamus or pituitary gland. These are parts of the brain that are directly responsible for the creation of gonadotropin releasing hormones and luteinizing hormones. A decrease in these hormone levels will result in a decrease in testosterone overall. Secondary hypogonadism can be the result of aging, obesity, the side effects of medications, or symptoms of an inflammatory disease.     


Although more common in women than men, it’s estimated that nearly eight million men in the United State have osteoporosis. This bone disease occurs when the body loses too much bone mass, creates too little bone, or a combination of both. One of the main causes of osteoporosis can be low levels of testosterone

Male Sexual Function 

Testosterone replacement therapy being used to increase sex drive and improve erectile function has produced mixed results at best. It’s fairly conclusive that this option is not as effective as PDE5 inhibitors such as Viagra®, Cialis®, or Levitra®However, testosterone replacement therapy may be an effective alternative option to avoid potential side effects associated with those medications. 

Miscellaneous Reasons 

Some people will undergo TRT without low levels of testosterone or a medical condition. The thought is that higher levels of testosterone can enhance sexual performance, achieve higher levels of energy, help with weight loss, increase muscle strength, and cultivate mass for bodybuilding. Generally testosterone replacement therapy will only help those that are experiencing low testosterone, but the extra testosterone could provide a moderate boost in some of these areas. Medical professionals generally agree that self-diagnosing or self-treating with TRT is unsafe.

What Are the Risks Associated With Testosterone Replacement Therapy? 

Documented potential side effects associated with testosterone replacement therapy include: 

  • Acne and oily skin
  • Blood clots
  • Breast enlargement
  • Chest pain
  • Deep vein thrombosis
  • Difficulty speaking
  • Enlarged prostate
  • Heart attack
  • High red blood cell count
  • Irritation at the location of the treatment 
  • Itching
  • Lower sperm count
  • Pulmonary embolism
  • Rash
  • Reduced HDL cholesterol
  • Shrunken testicles
  • Sleep apnea
  • Stroke
  • Swelling in hands or feet
  • Trouble breathing

The most severe side effects are typically rare, and even mild or moderate side effects are not common. If you are currently experiencing or are at an elevated risk for any of the conditions listed above, you may not want to pursue testosterone replacement therapy. A licensed physician can help make that determination.

The Takeaway

Testosterone replacement therapy is an effective way to increase testosterone levels in individuals who are experiencing low T. It's typically used in this with a medical condition that affects testosterone levels.

If you think that you may be experiencing low levels of testosterone, you may want to consider a blood test and find out if your levels are deficient or abnormal for your age. A trained physician can help. 

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Longitudinal effects of aging on serum total and free testosterone levels in healthy men. Baltimore Longitudinal Study of Aging

Muscular responses to testosterone replacement vary by administration route: a systematic review and meta‐analysis

Liver damage from long-term methyltestosterone

Testosterone Deficiency and Osteoporosis.

Testosterone for the aging male; current evidence and recommended practice

Understanding How Testosterone Affects Men | National Institutes of Health.

Risks of testosterone replacement therapy in men

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Disclaimer : This article is for information only and should not be considered medical advice. Always speak with your doctor about your health and the benefits or risks of any treatment or intervention. This information should not be relied on as a substitute for professional medical advice.