How to control oestrogen levels in men on TRT

control oestrogen levels in men on TRT

What is Oestrogen and Why is it Important in Men?

Oestrogen is often thought of as a woman’s hormone. Indeed, even some doctors think that oestrogen (or estrogen for the American spelling) is a purely female hormone with little to no effect on the male body.

In reality, oestrogen is a very important hormone for men and women, and it has many important functions in the male body.

Oestrogen ensures good joint health, maintains bone density, is important for libido and erections, and is needed for optimal mental health and cardiovascular health. However, it is also important to control oestrogen levels in men.

It is particularly important to know about this hormone for men who are on TRT. This is because testosterone converts into oestrogen in the male body, so when testosterone levels are increased through TRT, this can lead to an increase in oestrogen levels. This conversion is enabled by the enzyme aromatase, it does this by cleaving off some of the testosterone hormone to make it into oestrogen.

This YouTube video involves a long discussion about this hormone and its importance in men, on and off TRT:


The Negative Impact of Oestrogen on Men

Whilst oestrogen is important for a man’s health and wellbeing, if it is too high it can also cause several issues.

The main ones include:

  • Gynaecomastia (growing breast tissue/man boobs)
  • Being overly emotional (e.g. crying at films or adverts that you wouldn’t usually get emotional about)
  • Body fat gain in certain areas (around the stomach, hips and buttocks)
  • Low mood
  • Low energy
  • Reduced sex drive

On TRT, a man’s testosterone levels may be higher than they were previously used to, this can lead to increased oestrogen conversion from the aromatase enzyme in a man’s body.

As a result, the issues above can affect some men whilst on TRT, as well as some men who aren’t but have other factors that increase oestrogen levels.

Factors that Increase Oestrogen in Men

Some men have high oestrogen levels despite having normal testosterone levels, not being on TRT and even despite having low testosterone levels.

Men who naturally have high oestrogen levels often have higher body fat levels, stress, poor sleep or consume too much alcohol. In these instances, aromatase is often increased or the removal of oestrogen by the liver is impacted.

Some men also have higher oestrogen levels for genetic reasons.

Causes of raised oestrogen levels in men:

  • higher than normal testosterone levels
  • liver function issues (the liver is responsible for clearing excess oestrogen)
  • genetic disposition to higher aromatase levels
  • high alcohol consumption
  • stress, causing raised chronic cortisol levels
  • poor sleep
  • high body fat levels (body fat contains aromatase)

Having raised oestrogen causes a negative feedback loop which results in suppression of testosterone production. Thus some men have high oestrogen levels despite low testosterone levels. This tends to be seen in men with very high body fat.

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How to naturally reduce oestrogen levels in men

The best natural ways to reduce oestrogen levels include:

  • improving sleep quantity and quality
  • eating cruciferous vegetables that contain DIM (3,3′-Diindolylmethane)
  • losing body fat
  • exercising
  • reducing stress levels
  • consuming less alcohol
  • ensuring good liver health and function

All of these can be used in men who use TRT as well as those who are natural but have raised oestrogen levels.

If oestrogen levels are reduced in a natural person, this may cause an increase in testosterone levels.

Reducing oestrogen levels in men on TRT

In men on TRT there are some other ways to reduce oestrogen levels:

  • by using an aromatase inhibitor to reduce the conversion of testosterone into oestrogen
  • reducing the dose of testosterone taken, if levels are too high
  • splitting up the dose into smaller, more frequent doses to reduce spikes in testosterone and oestrogen
  • reducing the HCG dose, if this is being taken

Please make sure you discuss with your prescribing doctor before making any changes to your TRT protocol!

HCG causes higher production of certain types of oestrogen than exogenous testosterone alone, therefore sometimes reducing the dose of this taken, or splitting up injections into smaller ones, can lead to a reduction in oestrogen levels.


How do I know that I need to reduce oestrogen?

Oestrogen is a very beneficial hormone, even in men. Oestrogen is important for ensuring the health of a man’s cardiovascular system, cholesterol levels and mental health. It is also really important for libido and sexual function as well as sleep and bone/joint health.

It is therefore crucial for a man’s health that oestrogen levels are not reduced unnecessarily.

If your oestrogen levels are slightly above the ‘normal range’ and you feel fine, with none of the symptoms above, then reducing it through the use of an AI is likely unnecessary and can even be detrimental to your health.

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Are Aromatase Inhibitors Bad for Men?

Aromatase inhibitors (AIs) are an effective means of controlling oestrogen levels in men who can’t manage them through other means, or who are genetically disposed to having higher levels. It may also be a short term measure for men with higher body fat levels.

In all instances, body fat levels and lifestyle measures should be encouraged to reduce oestrogen levels and reduce the need for an aromatase inhibitor. However, this may not always be possible.

Are all aromatase inhibitors the same?

Not all AIs are the same. They have different potencies, slightly different methods of action – mainly due to how they bind to the aromatase enzyme, and different half-lives.

The two most commonly used in men are anastrozole and exemestane. This is because they are less potent than other AIs that may commonly be used in women for their licensed use – to treat breast cancer.


Letrozole is the most potent non-suicidal/steroidal aromatase inhibitor. It is considered too potent for use as an AI in most men on or off TRT. The risk of completely blocking aromatase activity and ‘crashing’ oestrogen levels is too high with this medication.


Anastrozole is a non-suicidal(steroidal) inhibitor. This means that it attaches to the aromatase enzyme temporarily, and then disengages. This can lead to a ‘rebound’ of oestrogen levels if it is not dosed correctly or the protocol is not optimal.


Exemestane is a suicidal(steroidal) inhibitor. This means that it connects to aromatase and is then ‘locked’ to it, preventing the enzyme from converting any more testosterone into oestrogen. This means that there is no rebound in oestrogen levels, but it can make crashing oestrogen more likely or slower to recover.

What is the best AI for Men?

What is the best AI to control oestrogen levels in men?

In general, exemestane is considered the best option. This is not only because it does not cause rebound, but because of other desirable attributes.

Exemestane does not affect a patient’s lipids as severely as anastrozole. This means it is safer for long term use.

Exemestane tends to allow for more even oestrogen levels, as it can be dosed less frequently and with no risk of a significant rebound. This means that you can consistently control the reduction in aromatase activity to give even oestrogen levels.


Oestrogen is extremely important for a man’s health and wellbeing. Doctors and patients should be very careful about controlling oestrogen levels and should always look to do it naturally in the long term, even if pharmaceutical means are used short term to reduce problematic oestrogen levels.

Exemestane is the AI of preference in most situations. A low dose of this, with frequent administration, leads to even levels of oestrogen and great results without crashing oestrogen levels.

Oestrogen levels should be carefully monitored on TRT to ensure that they are optimal, but oestrogen should be left alone if a patient is not seeing negative side effects despite slightly raised levels.

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