Testosterone Replacement Therapy: Time of Onset

TRT or Testosterone Replacement Therapy is a treatment for men who suffer from Low Testosterone, but exactly how long do you need to wait before you see resutls?

Hormone changes are a normal occurrence with advancement in age. Although the dramatic reproductive hormone change of menopause occurs rather suddenly in women, sex hormone changes in men are a gradual process that may span several decades.

By the time most men reach the age of 70 to 80 years, they have only about close to half the testosterone circulating in their blood that they had when they were in their 20s.

Testosterone is the main male sex hormone, responsible for the development of male reproductive organs, as well as the secondary sex characteristics that distinguish men from women, such as facial hair and a deep voice.

Testosterone also plays an important role in bone density and overall muscle health. Low testosterone, or “low T,” can cause a number of changes in men, both physically and emotionally. You can, of course, look at Testosterone Replacement Therapy.

What is Low Testosterone?

Low levels of testosterone is also associated with increased risk of lower urinary tract symptoms, metabolic syndrome, and even benign prostatic hyperplasia according to some studies.

Although low T can cause a number of different symptoms, not all men with low testosterone levels experience the same symptoms or experience them to the same degree. Typical symptoms of low T may include:

  • Fatigue
  • Reduced sex drive (libido)
  • Erectile dysfunction
  • Fewer spontaneous erections
  • Decreased muscle mass and strength
  • Body hair loss
  • Increased breast tissue
  • Hot flashes
  • Mood changes
  • Loss of bone density
  • Reduced cognitive function

Testosterone replacement therapy (TRT) is a testosterone treatment option for men with low testosterone levels. It is sometimes called androgen replacement therapy (ART), testosterone supplementation therapy (TST) or androgen therapy (AT). TRT can help men with low T levels improve their cognitive function, sexual function, build muscle mass, increase their energy levels and mood, and reduce their risk of bone density loss.

Let’s find out the details of what happens when you start taking testosterone replacement therapy, how long it takes to notice an effect, as well as a general idea on what to expect during this process.

Testosterone Replacement Therapy – TRT: What is it?

Testosterone therapy is a treatment in which testosterone (a hormone that plays a key role in the development and maintenance of masculine characteristics) is replaced with synthetic testosterone.

Testosterone therapy is typically only recommended for men with testosterone deficiencies (a condition known as late onset “hypogonadism”) that are causing symptoms like low sex drive, erectile dysfunction, reduced muscle mass and strength, and increased body fat.

TRT is not recommended as a treatment for men with “normal” testosterone levels or for aging-related changes in testosterone levels (known as “andropause” or “male menopause”).

Lastly, TRT is also not recommended as a way to improve athletic performance or to treat sexual dysfunction not caused by low testosterone levels.

It’s important to note that testosterone replacement therapy is not the same as anabolic steroid use, which is sometimes used illegally by athletes seeking to improve their performance and increase muscle strength. TRT is an FDA drug treatment that is medically supervised and designed to provide therapeutic benefits, while anabolic steroids are synthetic drugs that can have potentially serious side effects.:

Note: FDA cautions consumers that bogus products claiming to treat “low T” are flooding the market. These illegal products may not be safe and could cause serious side effects. To date, the FDA has not approved a testosterone product for treating “low T” that can be taken by mouth and purchased over the counterFactors That Might Be Impacting Testosterone Levels

Factors That Might Be Impacting Testosterone Levels

A variety of factors can contribute to low testosterone levels. Some of these are out of your control, while others may be related to lifestyle choices.

  • Age: Testosterone levels gradually decline with age. This is a normal part of aging and is not usually cause for concern.
  • Health conditions: Some health conditions can lead to low testosterone levels. These include obesity, type 2 diabetes, sleep apnea, and certain types of cancer.
  • Injury or infection: Injury or infection in the testicles can lead to low testosterone levels.
  • Medications: Some medications, such as steroids and opiates, can lead to low testosterone levels.
  • Hormone disorders: Hormonal disorders like hypothyroidism can lead to low testosterone levels.
  • Lifestyle choices: Certain lifestyle choices, such as substance abuse and smoking, can lead to low testosterone levels.
  • Diet: A diet that is low in protein and high in sugar and saturated fats can contribute to reduction in testosterone levels.

TRT: How it Works

TRT involves replacing the testosterone that your body is no longer producing with synthetic (man-made) testosterone. This can be done in a few forms of testosterone therapy prescription products, some common ones are:

  • Injections: Testosterone can be injected into the muscles every one to four weeks.
  • Skin patches: A patch can be applied to the skin every day and replaced with a new patch every 24 hours.
  • Gels: Testosterone gel can be applied to the skin once daily.
  • Implants: A testosterone pellet can be implanted under the skin every three to six months.
  • Oral tablets: Testosterone can be taken in pill form, but this is not as common due to the potential for liver damage.

Testosterone Therapy: How Long Does it Take for the Effects to Kick In?

So, how long does it take for testosterone replacement therapy to start working?

If you choose to start TRT, your doctor will likely stat by measuring your testosterone levels every few months to make sure there is a is a testosterone deficiency. Your doctor may also monitor your red blood cell production, hemoglobin and hematocrit levels (blood test that measures your red blood cells), and prostate health before and during TRT. You may also have your lipid profile checked (a measure of cholesterol and triglycerides) every six months or so.

It can take just several weeks or even a few months for the effects of testosterone therapy to be noticeable. In most cases, it takes about three to six months for men to see an improvement in their symptoms depending on method of testosterone administration.


Injections are typically administered on a once a week or biweekly basis. Majority of men will begin to experience the benefits of testosterone replacement therapy within two to four weeks of their first injection. The full effects of TRT may not be seen for four to six months.

Skin Patches

If you opt for testosterone skin patches, you will likely apply a new patch every day. The effects of testosterone replacement therapy usually become apparent within two to four weeks.

It was discovered that skin patches were 92% successful in delivering testosterone as quick as 24 hours in a clinical trial study conducted in 2017.


There are many different kinds of gels (nasal, oral, or transdermal – on the skin), but their usage is restricted to specific areas of the body. Typically, they are applied twice a day but some gels only need to be applied once a day. Another study (which is the same one described above) found that testosterone gel was 88% effective in delivering testosterone for 24 hours.

Some side effects associated with testosterone gels can include skin reactions such as itching, and redness at the site of application.

Note: this does not mean it is less effective than injections or patches, only that a smaller percentage of the testosterone was actually absorbed into the bloodstream in a 24 hour period.


Another testosterone replacement therapy is testosterone pellets, which are put under the skin, usually in the hip region. Under the skin, pellets of 2-3mm by 9-9mm are attached to the patient’s dermis via tiny needles that slowly release testosterone into the body over the course of three to six months.

While the effects might begin within a few days, significant results occur within 2-4 weeks of insertion. The reason for this is due to the pellet delivering a relatively low and steady testosterone levels as opposed to a sudden surge (such as what is seen with injections).

Oral Tablets

Another type of TRT treatment is oral tablets. Taking any sort of oral medication, on the other hand, causes some to enter the liver, thus testosterone is rarely taken in pill form owing to the risk of liver toxicity. Large amounts of testosterone metabolized by the liver is not good for your health.

That being said, there are some oral testosterone tablets that have been specifically designed to limit this effect and be easier on the liver.

The Short Term and the Long Term Effects of TRT

Figrue 1: TRT has a direct influence on male sexual and mental health

The physical symptoms of low testosterone may take months to go away, but you could notice certain advantages sooner. It’s critical to remember that each individual is unique. As a result, there is no way to know when the effects of testosterone therapy will begin to manifest exactly.

The Short Term Effects

It was observed in a study from 2011, testosterone replacement prescription users reported overall feelings of well-being within three weeks.

Sexual Health

Men reported to have experienced a higher sexual desire, as well as increased number of morning erections, and overall sexual life.

Mental Health

Other short term effects that were reported included increased sense of energy and well-being, improved mood and decreased anxiety.

Physical Effects

It was discovered in the same research from 2011 that testosterone replacement therapy can cause an increase in muscle mass and strength, albeit to a lesser extent than HGH.

The Long Term Effects

TRT will not work miracles and turn you into the Hulk overnight. It will, however, provide slow and steady results that last as long as you continue treatment. Studies show that on average, men on TRT for at least 2 months got the full benefits of the testosterone treatment.

Muscle Mass

One study showed men who had an androgen deficiency and were placed on TRT saw an increase in lean body mass, lean tissue, and muscle strength in just 12-weeks.

Bone Density

Another study showed that testosterone not only increased muscle mass but also improved bone mineral density in those with male hypogonadism. The same research was continued for 6, 8, and 12 months. An increase in bone density was observed throughout the entire course of the treatment.

Further studies are being done currently to see whether it would continue beyond the 12 months.


It is not all about the physical changes that you can see, but also the ones happening inside your body. Research shows that testosterone replacement therapy helps improve lipid profiles by reducing cholesterol and triglyceride levels while increasing HDL cholesterol levels.

Other studies showed a decrease in blood pressure in men after 3-9 months. In addition, improve sexual function, testosterone levels, and erectile function after at least three months on testosterone were improved.

The Bottom Line

As you can see, testosterone replacement therapy provides a wide range of benefits that improve your quality of life very quickly. Whether it is the short term or long term effects, there are many advantages to TRT for men with late onset hypogonadism, androgen deficiency, or any androgen deficiency syndromes and conditions associated with lowered testosterone production.

The most important thing to remember is that you need to consult with a doctor first, to see which treatment is right for you, to set a time frame that align to your goals for this treatment, and method of testosterone administration.

Because there are side effects, it is important to ensure you communicate with your doctor if you’re experiencing side effects.

Comments and questions?

Join our closed Facebook group and get custom answers from the community.

Drop us a comment down below and one of our expert coaches will respond to it.


Daniel Louwrens BSc PT

Daniel Louwrens BSc PT | Writer

Daniel Louwrens is a well-rounded fitness professional with over 10 years of experience in bodybuilding and fitness. He holds a BSc in Chemistry from the University of Western Cape and is a certified International Personal Trainer and Nutritionist. He is also a skilled bodybuilder and head coach for Muscle and Brawn. With his knowledge and expertise, he provides personalized training, nutrition, and recovery guidance to help clients reach their fitness goals.

Read all articles
Notify of

1 Comment
Newest Most Voted
Inline Feedbacks
View all comments
1 year ago

Thanks for your great work. I love your Site, bookmarked it and shared on Reddit.
From what I gather, the scrotal testosterone creams are the most effective and keel even therapies. Information on who offers this is tough to find, so I wonder if you have any advice on an industry standard resource in the U.S.?
Kind thanks in advance, Doug

Anti-Aging, Peptide, and Health Science Delivered to Your Inbox

Join 15,000+ readers keeping informed and staying up to date on all of the latest Peptide, TRT, and SARMs news, in only 5 minutes per week.

Don't like emails?

Join our Facebook group and get the same updates!