A Simple Guide to Popular Aromatase Inhibitors for Men

popular aromatase inhibitors for men

Patients who have hormone problems are often prescribed to use anabolic steroids as a way to support their growth. Aside from that, fitness buffs and athletes are taking advantage of this supplement to promote muscle growth to enhance their performance. However, since this type of steroid is man-made, it does come with some side effects. One way to be able to transition smoothly into steroid use without worrying about the potential side effects is to add Aromatase Inhibitors (AI) to your cycle. This guide aims to provide you with an in-depth view of its use and the more popular brands to use.

While you are on a steroid cycle, your body’s natural hormone production will be disrupted. Among the side effects that you will encounter is higher levels of estrogen. This is a normal outcome with the use of anabolic steroids, but it also comes with some side effects. Using an Aromatase Inhibitor will help you skip the side effects but be wary. Too much of a good thing can be bad for you. Also, if your estrogen levels drop, it will also affect your gains. In order to make the most out of this medication, having proper knowledge of its use is a must.

Importance of Estrogen

Everyone knows that men have high amounts of testosterone in their bodies. This is why this hormone is typically associated with the male species. However, men do have estrogen in their system too. You might not realize this, but the female hormone does play a part in your growth and development. 

The only difference between men and women is that the amount of testosterone is usually high in men compared to estrogen. The ratio between testosterone and estrogen in men is about 10 to 1. But there are several factors that can affect the levels of these two hormones such as age, diet, the kind of lifestyle you are living, and more. 

Effects of Steroids in Your Hormones 

aromatase inhibitors are frequently used

Anabolic steroids are synthesized testosterone hormones that are used to increase muscle gains and improve performance. With such huge benefits to someone who lifts weights or is working on becoming better at what they do, they often forget that steroid use can affect their hormonal system, specifically the amount of testosterone and estrogen in their bodies. This poses two issues on someone who is using steroids: having too much or too little estrogen in the body. 

Common Symptoms of Too High or Too Low Estrogen Levels

A sudden increase in estrogen levels can trigger a host of hormonal issues in men which can lead to these all too common symptoms: 

  • Gynecomastia
  • Reduced sex drive 
  • Exhaustion
  • Hot flashes or suddenly feeling hot 
  • Difficulty in focusing
  • Mood swings 
  • Puffiness or edema 
  • Enlarged prostate
  • Balding 

Like it was mentioned before, there are also potential side effects that can be triggered when estrogen levels in your system go down. Since estrogen is an essential component in muscle growth, the lack of it will make you lose any gains that you have. Aside from that, it will also cause these side effects to appear:

  • Osteoporosis or weakening of bones
  • Depression
  • Heart problems
  • Less pumping 
  • Compromised immunity

Now that you have a better understanding on why estrogen is an important hormone in your body, you should have more respect for it especially when it comes to building gains. That said, the next thing that you should know about is the process called aromatization. 

The Process of Aromatization

Aromatization occurs when the hormone testosterone is transformed into estrogen. This process is triggered when there is an excess amount of the male hormone in your system. Once your body detects this, it starts to work on converting it into a different type of hormone, like estrogen, specifically estradiol. The aromatase is the enzyme that does the conversion and is typically present in these areas of your body:

  • Adrenals
  • Blood vessels
  • Breast
  • Fat tissue 
  • Testicles 

On a good note, this particular enzyme is not harmful to the body. It serves a purpose and that is to convert the excess testosterone into estrogen. However, this leads to the formation of man boobs which men do find embarrassing at times. You can already see why this side effect is not something that bodybuilders and athletes are looking forward to.

Factors that Affect Aromatization

It may seem that the process is pretty straightforward for some but it is not. In fact, the process varies from one person to the next. There are some who do not have any side effects while others exhibit the symptoms mentioned above. There are three factors that may play a part on how aromatization works for them. These are:

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Did you know that as you age, the estrogen levels in your body goes up? This is because your testicles are aging. Though the female hormone is not directly contributing to the aging process, it still has a part in it.


Your genes play a part in the aromatization process in your body. This is because no two people are the same. Our genetic makeup varies even if we just come from the same bloodline. Even the smallest change in our hormonal system and how our body responds to this can have a different result. Basically, your genes can contribute to whether you will be experiencing side effects for a medication you are taking or not. Yes, the basic functions in our body work the same way with others, but there are differences too. This is why no two people will experience the same reaction when taking steroids. 

Percentage of Body Fat

The amount of body fat in your body is heaven for estrogen production. This is why those who are overweight or obese are more at risk of suffering from hormonal problems in the long run. This can even lead to chronic obesity which is difficult to reverse.

Which Steroids Aromatize More or Less?

Aside from the factors mentioned above, another thing that you should know about aromatase is that some steroids tend to aromatize more compared to the others. Take a look below. 

Most Aromatizing Steroids

These steroids are designed to help you bulk up, but it can also lead to the formation of man boobs due to water retention. Some do take these steroids but in order to minimize the side effects, they pair it with Aromatase Inhibitors.

  • Dianabol or Methandrostenolone
  • Testosterone esters like Propionate, Enanthate, and Cypionate
  • Anadrol 
  • Methyltestosterone 

Less Aromatizing Steroids

The good news is that taking Trenbolone will not lead to developing man boobs not unless you are sensitive to it. This is because it can affect your prolactin. High amounts of prolactin in your system can lead to the development of bigger breasts in men. However, this happens rarely but this is one option to consider if you want to bulk up minus the man boob. 

  • Trenbolone 
  • Anavar
  • Stanozolol
  • Nandrolone

Take note that you will not be using Anavar solo. You will need to complete the stack using testosterone to avoid shutdown.

The Dangers of Boldenone 

There is one particular type of steroid that stands out in relation to its use with Aromatase Inhibitors which is Boldenone. Boldenone is a type of steroid that is designed to be a derivative of testosterone. Athletes sometimes use it to enhance their performance as well as muscle strength. 

Although it may seem like a useful type of steroid, you should never use it together with an AI. This puts you at high risk since Boldenone has been found to reduce estrogen levels while you are on a cycle. Since AI is used to reduce estrogen levels the compound effect can cause many unpleasant side effects that you could have easily avoided. 

The combination of this synthetic steroid and AI can lead to weakening of your bones, deteriorating nervous system, and affect your liver function too. What’s worse is that once these side effects have been triggered, it is difficult to go back to your normal state. This is why you should NEVER take these two together.

SERMs and AI – What’s the Difference?

One of the most common misconceptions that people make with SERMS or Selective Estrogen Receptor Modulators and AI is that they are the same. This may be due to the use of the concept of anti-estrogens that is being bandied about. But what exactly are these two? 

SERMs are designed to stop estrogen receptors in the body in order to prevent more of this hormone to be produced especially when the amount of estrogen in your system is way too high. This is one of the reasons why Clomid or even Nolva is recommended during the PCT stage to speed up the recovery phase. In fact, two to three decades ago, athletes had been using Nolva on their cycle. Though some have reported that they had positive results with it, their gains were a different matter. 

Aromatase Inhibitors, on the other hand, focuses more on preventing the aromatase enzymes instead. This medication is designed to prevent your body from producing high amounts of estrogen. Instead, a trickle of estrogen will be released in your system. Another plus to the use of AIs is that their effects occur faster compared to SERMs since the latter requires more time to take effect. For AI, it will only take up to 2 hours for you to feel its effects. This is one of the reasons why it is better to use SERMs for the PCT phase and AI for your mid-cycle to get the best results for you. 

Classification of Aromatase Inhibitors

Aromatase Inhibitors are typically classified into steroidal and non-steroidal which can be tricky at times. Here’s how these two differ: 

Steroidal Aromatase Inhibitors 

This type of AI changes the enzymes completely to the point that they can no longer function the way they are supposed to. When this happens, the effects are irreversible. Among the AIs that fall under this category are: 

  • Testolactone and Formestane – These are 1st and 2nd generation AIs. Formestane was first used for breast cancer treatment but it is no longer in circulation. 
  • Exemestane – This is the only 3rd generation AI and is more potent compared to Formestane. Another plus to using this medication is that it can be taken orally. 
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Non-Steroidal Aromatase Inhibitors

Non-steroidal AIs are designed to bind themselves to the aromatase enzymes via non-covalent interactions. Unlike SAIs, NSAIs are reversible so you don’t have to worry about experiencing spikes in your estrogen levels. Examples of NSAIs are: 

  • Anastrozole and Letrozole – These two are typically the first line of treatment for metastatic type of breast cancer. They are also considered as adjuvant treatments. 
  • Rivizor – This is an example of third generation NSAI that is highly potent in treating advanced breast cancer compared to the early generations. 

These classifications are usually enough for those who have been studying these compounds and their effects in regular TRT as well as cancer prevention. But this is quite different when pairing it with your anabolic steroids. It is important that you are aware of how to range these AIs based on their dosage and power. The most powerful Aromatase Inhibitor at the moment is Letrozole (Femara). This is just one type of AI in the market, but to understand it better, we should compare it to two more AIs that are quite popular recently.

A Look at Popular Aromatase Inhibitors

Understanding the effects of Aromatase Inhibitors in terms of using them in conjunction with anabolic steroids is important. This way, you will be able to decide which is better for your gear and when to use them. Here are the top three Aromatase Inhibitors that are currently in the market. 

Letrozole (Femara)

Like it was mentioned before, this is currently the most powerful non-steroidal Aromatase Inhibitor in the market. Studies have shown that this NSAI can block up to 98.4% of aromatase cytochromes and even bring down the amount of the estrogen estradiol in the blood. In fact, health experts as well as fitness gurus recommend that this AI should be taken once every three days because of its potency. 
Another plus as to why Letrozole ranks high in the list of NSAIs is that it doesn’t have any effect on other hormones. You can use it together with the current gear or anabolic steroids that you are using but make sure that you are not experiencing negative effects with it. Take note that you should not use this during PCT since it may have an adverse effect with your use of SERMs. The danger here is that it can cause your estrogen production to completely shut down. If you want to know more about Letrozole, its uses and side effects, read this Letrozole guide.

Arimidex (Anastrozole)

Arimidex or Anastrozole is one the rivals of Letrozole and with good reason. Though Letrozole is best known for its better inhibition of aromatase enzymes, these two are similar in some ways. For starters, both fall under the non-steroidal AI category. Second, their effects are reversible. In terms of differences, Arimidex has been found to cause side effects like bone pain, spike in blood pressure, as well mental issues. Letrozole, on the other hand, has been found to cause sleep problems, upset stomach, as well as depression. With regards to dosage, you can purchase Arimidex in 1mg pills while Letrozole can be bought at 2.5 mg pills.

Which one is better? The medical community is of two minds on which of these NSAIs is better than the other. There are some specialists that put Letrozole at the top with numerous studies backing up their findings, but the same goes true to those who champion Arimidex. Even recent studies on 45,000 patients within 65 months who are using these two NSAIs show minimal differences. Basically, you are the one who will decide which is better for your current condition.

Aromasin (Exemestane)

Aromasin lists Exemestane as its active ingredient which is classified as a steroid. This puts this AI in a different category altogether. Like it was mentioned before, steroidal AIs bind to the enzyme and alter its design to the point that it no longer works like before. Unlike Letrozole and Anastrozole, the effects of Aromasin are irreversible. That said, this drug is often referred to as the “suicide inhibitor”. However, people are still using it as part of their cycle. 

A word of caution for those who are using this steroidal AI. There is a possibility that the estrogen levels in your body can spike after your course finishes. Though it is rare in athletes, you still need to pay attention to any effects to your body. While on cycle, you don’t need to go beyond 12 5mg pills every other day. Healthcare specialists may require 25 mg for those who have gynecomastia. When taking higher dosage, you only need to use it one week as opposed to the lower dosage which can be taken up to 2 to 3 weeks. You can read more about Aromasin in this guide

Side Effects to Watch Out For when Using AIs

side effects to watch out

Using Aromatase Inhibitors can affect your hormonal system severely unless you know how to use them properly. Among the areas that are affected by this medication are: 

Central Nervous System 

This is usually the first one that is affected with the use of Aromatase Inhibitors. Extensive use or taking higher dosage of AIs can result in aggressive behavior or excessive nervousness. Some athletes have taken note of sleep issues wherein they feel that they haven’t slept for an entire week or they have a hard time falling asleep. These side effects are not unusual for those who are using AIs but it can be managed by reducing one’s dosage. However, you should not counter the sleepy feeling with uppers like coffee and other caffeinated products because they can tire out your nervous system even more. 

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GI System

Your digestive system will not be able to escape the effects of Aromatase Inhibitors, especially when taking them orally. It is highly likely that you will experience the following:

  • Vomiting
  • Diarrhea
  • Flatulence
  • Nausea
  • Lack of appetite


Taking AIs can have an effect on your blood work which can put a strain on your heart. Although there are some instances when your blood pressure can go up when taking AIs, there are no reports of heart attacks happening. Even if this means that it is less likely to happen, it is best that you monitor your condition and avoid drinking alcoholic beverages in the meantime. 


Another area that AI can affect is your liver. Though the toxicity levels are not as bad compared to taking 17-alpha-alkylated steroids, it can still affect its function. In severe cases, athletes have taken note that their HDL levels dropped considerably.

Aside from these general areas, Aromatase Inhibitors can also induce the following side effects: 

  • DVT
  • Compromised immunity
  • Dry or ruptured tendons
  • Allergic reaction
  • Increase in creatinine levels 

On a good note, these side effects will vary in severity based on the dose that you are taking as well as your body composition. Like it was mentioned before, people have different reactions when it comes to taking Aromatase Inhibitors.

Tips to Avoid the Side Effects when Taking Aromatase Inhibitors

tips to avoid the side effects

You might be wondering if there are ways to avoid the known side effects associated with Aromatase Inhibitors. As much as we all want to enjoy a medication without dealing with the side effects, there will always be an instance where you will experience some. This includes the use of AIs. That said, there are a few tips on how you can reduce the effects somewhat by doing the following: 

  • Avoid taking any recreational drugs and alcoholic beverages. 
  • Focus on having a healthy diet. Skip junk food. 
  • Pay attention to what your body is telling you while using AI such as your mental and physical state. 

Any side effects that you are feeling can be minimized by lowering the dosage that you are taking. If not, it is possible to use a different Aromatase Inhibitor. There should be some improvements within 2 to 3 days. If you are still experiencing side effects, stop the course entirely. 

How to Monitor Effects of AI

If you are planning on using Aromatase Inhibitors along with your Anabolic steroids, but don’t want to experience severe side effects, there is one thing to do and that is to take tests. This means that you will have to take three blood works at strategic times. Here’s what you need to know: 

Test 1 – 1 Month Prior to Cycle

Getting a blood work a month before you start your cycle will give you an idea on what your current estrogen level is. This is the time when your blood is still clean.

Test 2 – 2 to 3 Weeks into Your Cycle on Short Gear/ 3 to 4 Weeks on Long-Acting Compounds

Your second test will give you insight on what your current estrogen levels are while on gear. The results will also show the speed in which your body processes AI so that you will be able to adjust your intake accordingly. 

Test 3 – One Week After Taking the Last AI Pill 

The final test is to determine whether your testosterone and estrogen levels are back to normal just like in the first test.  

Just to give you an idea, the normal estrogen levels in males is around 160. During the second test, many have noticed that theirs has gone up by 20 points. There are some who may not feel any changes to their bodies while others feel the effects. Again, the results will vary depending on your body composition. 

Should You Avoid Testing While on AI?

There is simply no reason why you should avoid getting tested when you plan on adding Aromatase Inhibitors to your gear. Keep in mind that balancing your estrogen levels while taking anabolic steroids for your fitness goal is important. This way, you will not suffer from severe effects like gynecomastia which will be more expensive down the road. 

Is Using Aromatase Inhibitors Worth It?

People are more inclined to try out performance enhancement drugs in the bodybuilding world. This is because they want to experience gains quickly to give their performance a boost. That said, Aromatase Inhibitors are frequently used but they should not be taken lightly. After all, they are designed to inhibit your body’s estrogen production which, when taken in large doses, can cause severe side effects. 

However, for those who are willing to take the risk, it is not that easy to determine which of the three AIs you should use. But if it is for a long-term TRT, Anastrozole is a good option to start with. You can opt for Letrozole if your liver is reacting to other Aromatase Inhibitors. Regular doses of TRT usually range from 50 to 150 mg each week. However, in the case of athletes and bodybuilders, the dosage can go up to 750 mg per week. You can actually see the difference between the two. This is why it is important that you select the right option for your gear because using one is better than not having it especially when using anabolic steroids.

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