Why Do I Feel So Tired After a Testosterone Shot? (5 Science-Baked Reasons)

A testosterone shot is one of the most widely utilized methods for testosterone replacement therapy (TRT). 

Exogenous testosterone is administered directly into the bloodstream for physical performance enhancement or to compensate for low levels of testosterone. 

When it comes to the potential side effects of TRT, many patients experience low testosterone symptoms and tiredness after months of being on a TRT program.

If you are somebody who is concerned about their overall health because you’ve been feeling more tired than usual after receiving a dose of TRT, it’s crucial for you to first identify the reasons it is happening and learn how to properly address the symptoms!

This article serves as a comprehensive guide to the potential side effects of a testosterone shot and why you may feel exhausted after an injection. It will provide scientific data and share key insights into the following areas: 

  • Major reasons for experiencing fatigue after a testosterone shot 
  • How to manage fatigue after a TRT shot.

Are you looking for complete information on low energy levels after a TRT dose and ways to prevent it? Let’s get started!

5 Science-backed reasons why you feel tired after a testosterone shot

5 Science backed reasons why you feel tired after a testosterone shot

According to a study by The International Journal of Environmental Research and Public Health in 2019, the most frequent factors shared by men who are receiving treatment for low testosterone include low testosterone, energy, libido, and well-being. 

TRT injections have been gaining immense popularity as a treatment option due to their accessibility and effectiveness towards these factors.

Testosterone shots are generally safe for many people, but they can come with certain risks and side effects depending on the individual and their condition.

Counterintuitive to its main benefits, exhaustion is one of the most common symptoms experienced by those undergoing testosterone replacement therapy. 

Let’s break down some of the primary culprits for feeling fatigued after injecting a dose of TRT:

1. Testosterone increases red blood cell production

An abnormal rise in red blood cell production can sometimes occur with testosterone treatment causing you to feel tired. 

Testosterone helps regulate erythropoietin (EPO), which is a hormone released by the kidneys that is responsible for allowing the bone marrow to produce red blood cells. 

Testosterone is also an integral component in the metabolism of iron and helps form hemoglobin. It is an iron-rich protein in charge of bringing oxygen from the lungs to other organs. 

TRT plays a significant role in raising hemoglobin levels and hematocrit or the ratio of red blood cells to the overall volume of blood. 

Testosterone replacement therapy can also prevent the secretion of hepcidin (a peptide that regulates iron absorption), which in turn, increases red blood cell production. 

2. Testosterone increases muscle mass

Testosterone is one of the most important elements in muscle growth and development. TRT shots are able to tell the body to produce more lean muscle by attaching itself to muscle cell receptors. 

These signals trigger an increase in protein synthesis to grow more muscle tissue at quicker rates.

One of the most documented effects of testosterone replacement therapy is an increase in lean body mass

It is also typically accompanied by gains in muscle strength. Although leaner body mass can lead to more energy, TRT can play a role in making you feel tired if your hormonal balance is not optimal.

3. Testosterone can increase your metabolic rate

Aside from its muscle-building properties, testosterone is also known for increasing your body’s metabolic rate

This is because the amount of muscle you have is responsible for regulating your weight; increased muscle will require more energy to maintain. The greater the muscle mass, the more calories are burned with your metabolism firing at a higher rate! 

When testosterone levels are lower than normal, muscle mass declines and this is what ultimately causes your metabolism to slow down. 

Testosterone replacement therapy can help your body regulate the breakdown of fat for energy by enhancing its metabolic performance.

However, studies also show that an imbalance in hormones paired with intense exercise can lead to metabolic fatigue and exhaustion through overstimulation. 

4. Testosterone can disrupt sleep patterns

Having low testosterone is connected to poor sleeping habits and vice versa. A study in 2018 by the American Journal of Men’s Health revealed that men who are deprived of sleep have lower testosterone levels than those who get adequate sleep. 

The study shows that regardless of age, body mass, and exercise frequency, testosterone levels are heavily associated with sleep duration.

High testosterone levels, on the other hand, have also been shown to have adverse effects on sleep. These high levels are linked to shallow sleep and feeling more tired as a result. 

Steroid abuse or elevated hormone levels from testosterone replacement therapy can lead to insomnia and difficulties concentrating due to a lack of quality sleep. 

5. Testosterone can cause side effects such as anxiety and depression

Low testosterone can lead to a wide range of physical and emotional symptoms for many people. 

When the production of testosterone increases, decreases, or fully stops, another hormone might also respond in a volatile manner. This will lead your body to have hormonal imbalances that can develop into serious conditions.

Testosterone therapy has been shown to be effective in treating men with mood disorders or cognitive impairment due to low testosterone deficiency

However, every time you get an injection of testosterone, your hormone levels will rapidly increase but decline as your body adjusts to a normal balance of hormones. 

These fluctuations in hormone levels can lead to fatigue and other symptoms like depression and mood destabilization.

Tips to deal with fatigue after a testosterone shot

One of the biggest commonalities among the side effects of testosterone therapy is the persistence of low testosterone symptoms such as decreased libido and low energy levels even after starting a TRT program. 

By following the right measures and protocols, you can ensure that you have enough energy in the tank to get through your day without feeling completely exhausted. 

Here are some of the most effective ways to manage and avoid feelings of fatigue after a TRT injection:

1. Rest

Getting enough restful sleep each night is one of the most important pillars for maintaining good health. 

When your body doesn’t get enough rest, it won’t be able to function properly and leave you feeling exhausted as a result. 

According to a study, you should aim to get 7 – 9 hours of quality sleep each night to ensure that you are well-rested.

2. Stay hydrated

Making sure that you are hydrated and regularly consuming a balanced diet is crucial for managing fatigue after a testosterone shot. 

Providing your body with the nourishment it requires to function at its best means drinking enough water and eating nutrient-dense foods. 

Fruits and vegetables can significantly prevent fatigue and keep your energy levels up throughout the day. 

3. Regular exercise

Staying on a consistent exercise program can help naturally boost your energy levels by increasing oxygen delivery to your organs and muscles. This can help combat feelings of exhaustion throughout the day. You should ideally aim for 30 minutes of moderate-intensity workouts like swimming or walking intermittently each week to keep your body active.

4. Consider over-the-counter medications

Some people use prescribed and over-the-counter stimulants to help ease fatigue from testosterone therapy injections. 

Caffeine is proven safe and effective in helping combat drowsiness and fatigue. Pharmaceutical products like NoDoz and Vivarin contain around 200 mg of caffeine in each and should not be taken more often than every 4 hours.

5. Talk to your healthcare provider

People should always consult their doctor or healthcare provider for any questions or concerns regarding testosterone shots. 

If you are experiencing fatigue after receiving a dose of testosterone, you should get in touch with them for further evaluation. Your doctor may change your dosage and protocol if your hormone levels show irregularities.

6. Monitor for any unusual symptoms

Side effects are always a possibility and should be discussed with your doctor prior to receiving a TRT injection. Keep an eye out for additional symptoms that may come about. 

Some of the most common side effects include fluid retention, acne, and mood changes. If you observe any side effects after getting a testosterone shot, your doctor may adjust your treatment plan if needed.


Is it normal to feel tired after taking testosterone?

Yes. Testosterone Replacement Therapy (TRT) patients commonly experience tiredness and low testosterone symptoms even after months of being on a testosterone therapy program.

What should I feel after a testosterone injection?

For many patients who just started receiving testosterone injections, small incremental improvements can be observed within the first 3 to 4 days. During the first week, you will get noticeably better sleep and feel stronger if you are exercising.

How long does it take to feel better after a testosterone shot?

According to a study, it can take up to about 2 to 6 weeks for testosterone shots to begin taking full effect. The research also suggests that an improvement in overall quality of life can manifest within 3 to 4 weeks.