How Long Does TRT Take to Work? (Effects & Results Timeline)

James Cunningham, BSc, CPT
Published by James Cunningham, BSc, CPT | Staff Writer & Senior Coach
Last updated: May 7, 2024
FACT CHECKED by Dr. Kristy Dayanan, BS, MD
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Many men head into testosterone replacement therapy (TRT) with the expectation of instant results, especially when it comes to medical treatments that involve injections.

And while testosterone injections work very quickly to raise your T-levels, the actual benefits can take some time to fully develop.

So, to help our readers better understand what to expect, I spent a few days looking into the matter, and I went over the scientific literature on how long it might take to see results from TRT with a doctor.

The most interesting thing is how different parts of your body react over time.

Quick Summary

  • Testosterone replacement therapy can take anywhere from a few weeks to several months to fully impact all the different areas of your body.
  • While testosterone injections may raise your low T levels within days, it can still take a few weeks before you feel results from the hormone therapy.
  • Long-term benefits of TRT, such as enhanced libido, stronger bone density, increased muscle mass, and improved athletic performance, may take several months to manifest.
  • With the right type of treatment and regular monitoring of the outcomes with a doctor, you can achieve some significant health improvements.

How Long Does It Take for Testosterone to Increase With TRT?

A doctor talking to a patient about TRT result timelines

It can take anywhere from a few hours to a week for testosterone to increase with TRT. And it all depends on the type of testosterone replacement therapy and the dosage that a doctor recommends.

I know that might sound like a crazy long-range plan, but there is a good reason for that.

It’s also important to highlight that having a measured increase in low testosterone doesn’t automatically mean that you’ll see immediate improvements in your health.

Let me explain.

If a doctor prescribes a high dose of testosterone injections every five days, then you could have a measurable increase in serum testosterone within hours.

Doctors generally say that you’ll get the peak measurement after about 48 hours, and then it will gradually decline [1].

Compared to testosterone injections, a topical testosterone gel could take several weeks to significantly build up low T levels.

However, these gels have the advantage that they tend to provide a more stable level, and, of course, you don’t have to be concerned about injections.

You also have to factor in how high the dose is and how often you get the treatment. The higher and more often you take TRT injections or a gel, the sooner you’ll notice an increase.

Short-Term Effects of Testosterone Therapy

A doctor checking the testosterone effects on a patient

In this section, I want to address how long it will take to notice some of the short-term effects of taking testosterone injections or gels.

And I have broken it down into four benefits.

1. Increased Physical Energy Levels

One of the first things a lot of people notice after starting testosterone therapy is that they start feeling less fatigued and more energized [2].

It’s not like you’ll turn into The Hulk within days. But it would be quite common to start noticing more physical energy for activities like walking, running, or resistance training.

Based on my experience and feedback from a doctor, you could expect to feel this within 3–5 weeks.

2. Increased Mental Clarity

Another key area where hormone replacement therapy can make a big difference is in brain performance and mental energy [3].

As a personal trainer, I’ve had a lot of clients tell me that they felt more focused and motivated after 2–3 weeks of testosterone levels being back in the normal range.

And it seems to primarily reduce the amount of brain fog you get throughout the day, where you just struggle to keep your mind on one task.

3. Improved Mood

A person with high testosterone outside in a good mood

Many people associate testosterone with macho and aggressive male behavior.

And while that can be related, it’s important to note that low testosterone levels can have a serious impact on mood and mental health.

Research also suggests that testosterone and depression can have a significant correlation [4].

4. Stabilized Blood Sugar

And the last short-term impact a doctor highlighted during our research is that low testosterone levels can negatively impact insulin sensitivity.

What’s most interesting is that insulin sensitivity may increase within days of raising your T levels [5].

And that could significantly reduce blood sugar spikes and make weight management a lot easier.

Long-Term Effects of Testosterone Therapy

A high testosterone male stretching

Now, let’s turn to some long-term benefits that might only start kicking in after a month or two. For some men, it may also be a slow and gradual improvement over several months.

1. Improved Libido

Low testosterone levels can have a significant impact on sex drive. And I have to highlight that low sex drive isn’t the same as erectile dysfunction (ED) [6].

What this means is that testosterone therapy isn’t a solution for ED, but it could be an underlying issue of low sex drive.

It seems like men start to notice improvement in libido after about six weeks, and this can gradually improve further over the months ahead.

“Your libido is powered in part by your overall physical health, including your genes and hormones such as testosterone.”- Melinda Ratini, MS, DO

2. Strengthened Bone Density

A doctor looking at bone density

Testosterone plays an important role in bone tissue development, but it can take quite a while to see significant improvements [7].

Even when free testosterone is raised quickly through injections, it can take months for the body to build up bone density.

If this is one of the reasons you’re planning TRT, then talk to your doctor about possibly having a DEXA scan before and after to measure the improvements [8].

3. Increased Muscle Mass

Another reason a lot of men consider hormone replacement therapy is to improve their lean body mass.

Yes, some bodybuilders and athletes abuse it, but age-related muscle wasting can become a problem [9].

With the right exercise routine, diet, and hormone treatment, you should be able to notice improvements in lean muscle mass after about a month.


4. Better Athletic Performance

A person doing athletic workouts at the gym

I already mentioned above that low testosterone levels may result in low physical energy levels.

What’s even more interesting is that bringing T-levels back to normal could also help you boost exercise performance and endurance [10].

It’s unclear how soon this might happen, but my own experience was that I saw performance benefits after about 6–8 weeks.

5. Healthier Cardiovascular System

There are still many ongoing studies to better understand the link between cardiovascular health and low testosterone levels, but there are indications that there is a correlation [11].

It seems like more doctors are now paying attention to how testosterone treatments can be used as part of a comprehensive approach to heart health.

Related Post: TRT Before And After

Paying Attention to Your Body

A person working out at the gym

While I was doing this research with a doctor, he mentioned one thing to me that he recommends all men do once they start testosterone treatment.

Start keeping a daily journal where you write things down about how you physically and mentally feel.

Also, write down any differences you notice, like changes in body hair, feeling less stressed, increased or decreased energy, sexual function, and anything else that comes to mind.

During repeat consultations, your doctor will ask you questions about changes in how you feel, and he will compare them to your results from hormone tests.

What this does is provide a full picture of how well the treatment is working, and it helps to make educated and measured changes to the dosage.


How Long Does It Take for TRT to Peak After Injection?

It takes about 24 to 48 hours for TRT to peak after injection. This is the general medical guidance used, and it may depend on the dosage and frequency of previous testosterone injections.

How Long Does It Take for Testosterone Replacement Therapy to Increase Energy?

It takes about 3–6 weeks for testosterone replacement therapy to increase energy. A lot depends on other underlying conditions, your diet, and your activity levels, but most men will start noticing changes after about three weeks.


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About The Author

James Cunningham, BSc, CPT
Staff Writer & Senior Coach
James Cunningham, BSc, CPT holds a BSc degree in Sport & Exercise Science from University of Hertfordshire. He's a Health & Performance Coach from London that brings a unique blend of academic knowledge of health supplements and practical exercise experience to the table for his readers.
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Dr. Kristy June Dayanan, BS, MD is an author with a BS degree from University of the Philippines and an MD from University of Perpetual Help System. Her ability to simplify medical science complexities and dietary supplement jargon for the average reader makes her a valued medical fact checker and reviewer.
Learn more about our editorial policy
Dr. Harshi Dhingra, MBBS, MD is a published peer-reviewed author and renowned physician from India with over a decade of experience. With her MBBS from Bharati Vidyapeeth and an MD from Rajiv Gandhi University, she actively ensures the accuracy of online dietary supplement and medical information by reviewing and fact-checking health publications.
Learn more about our editorial policy

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