Should I Use An Estrogen Blocker?


Written by Elite HRT on June 15, 2021

Medically reviewed by

Camille Freking, Regulatory Affairs Specialist, MEDICAL ADVISOR

Estrogen blockers, also called aromatase inhibitors, are medications that are given to block the formation of estrogen in the body. Using an estrogen blocker can be a useful tool for certain things such as cancer therapy and endocrine therapy. 

Estrogen blockers are used for a comprehensive approach to testosterone replacement therapy and can be helpful in keeping the body in balance. 

Keep reading to learn more about the role of estrogen in the body, what estrogen blockers are, how they work, when to use them, the benefits, side effects, and of course where to get them. 

The Role of Estrogen in the Body

Estrogen is traditionally thought of as a female hormone and is used for female cycles like the menstrual cycle. However, estrogen is also available in males and is created in small amounts by the adrenal glands. Estrogen in men is in the form of estradiol. Estradiol is important in men for sexual function and desire, bone health, and more. 

However, too much estrogen is not a great thing. When estrogen levels are too high in men it can cause issues like breast growth, erectile dysfunction, slowed growth, and even infertility. Other symptoms that may occur are low libido, fatigue, hair loss, less muscle mass, and other symptoms that are similar to those associated with low testosterone levels. 

Keeping estrogen levels in men in balance is very important and if they are not it can lead to some unwanted side effects that could have long lasting implications.  

What Are Estrogen Blockers?

Estrogen blockers are medications that prevent testosterone from transforming into estrogen, and are also known as aromatase inhibition. This helps the body to keep the levels of testosterone up and reduce the amount of estrogen. Some of the common estrogen blocker medications are Arimidex (anastrozole), Femara (letrozole), and Tamoxifen Citrate. Both of these medications help to block estrogen production in hopes of balancing the hormone levels in the body for more normal range total testosterone levels and reduced high estrogen levels. 

How Do Estrogen Blockers Work in the Body?

Estrogen blocker’s main focus is not to block the ovaries or adrenal glands from producing estrogen, instead it is blocking the process of aromatization, i.e. aromatic inhibition. Aromatization is the process of testosterone converting into estrogen. 

The structure of a testosterone molecule includes a nonaromatic ring. This nonaromatic ring can be converted to an aromatic ring during the process of aromatization and the process is sped up by the enzyme aromatase, which is a P450 enzyme.

 When estrogen blockers are taken it stops the enzyme aromatase from working and transforming the androgen testosterone into estrogen. 

Indications for Estrogen Blockers

There are two main indications for using estrogen blocking medications: testosterone replacement therapy and for cancer therapy. The medication works the same way in the body for each indication, however there are separate benefits related to the pathology that is occurring. 

During Testosterone Therapy

When thinking about testosterone replacement therapy it is common to only think about taking testosterone hormone for treatment. While some people do only take testosterone for their hormone deficiency, taking a comprehensive approach to the problem can be very beneficial. 

Comprehensive testosterone hormone therapy can include medication such as HCG and aromatase inhibitors. The use of these medications helps to diminish side effects as well as enhance the testosterone amount naturally. 

Low testosterone is only one of the problems in men that have decreasing levels of testosterone with age and other causes. Because the body naturally converts testosterone into estrogen through aromatization even with testosterone hormone replacement, you could be converting it into estrogen and not getting the benefits you are looking for. 

By utilizing an estrogen blocker you prevent this from occurring and reduce the amounts of high estrogen and low testosterone. Using these medications together make the treatment more efficient and it’s something that your doctor will likely consider when creating a personalized treatment plan for you. 

Cancer Therapies

Aromatase Inhibitors have also been used for treatment of women with hormone receptor-positive breast cancer. Reducing the amount of estrogen can help the tumor size to shrink and assist with managing the breast cancer cells. It has also been shown to reduce the risk of breast cancer developing in women. 

This benefit is mostly in women after menopause that are at an increased risk for breast cancer. While the FDA has not approved the use of aromatase inhibitors for reducing breast cancer risk, there are some research studies that have shown this effect. Further research will need to be done to determine the efficacy of reducing breast cancer risk. 

Who Should Use Estrogen Blockers?

You shouldn’t only use an estrogen blocker if it has been recommended and prescribed by your doctor. Estrogen blockers are most commonly used for testosterone replacement therapy and cancer therapy and prevention. However not everyone that is receiving these therapies will be a good fit for estrogen blockers. Talking with your doctor about your symptoms and experience is important so that you can take medication that is right for you and will give you the most benefit. 

Benefits of Estrogen Blockers

The benefits of estrogen blockers will depend on what you are taking the medication for. But, no matter what you are taking them for it is most likely going to improve your quality of life. Removing unwanted symptoms and enhancing your other treatments makes estrogen blockers a great addition to many treatment regimes. 

When taking estrogen blockers with hormone replacement therapy there are specific benefits that make the medication so useful. The first is that it works with your body chemistry to simply prevent the conversion of testosterone to estrogen. During aging you want to preserve as much testosterone as possible, so by helping to prevent the aromatization process you can help to keep the testosterone your body has worked so hard to make, increasing your “free” testosterone levels. 

The other big benefits are the physical benefits. You may see its effects in the mirror. Estrogen blockers help to prevent the formation of gynecomastia, or large breast tissue. The other location you might see a difference is the reduction of body fat. You may see less fat in the abdominal area and reduce the amount of water that is retained in the body. This can all help you to look and feel your best. 

Side Effects of Estrogen Blockers

Estrogen blockers are generally very safe when used correctly. However, there are some more serious side effects. The largest side effect is the importance of estrogen in bone health and development. If the levels of estrogen are blocked too much and for too long it could impact the bones. This can show up as joint pain or stiffness. It could eventually lead to bone fractures if the bones become too weak. To counteract this there are some medications that can help to strengthen the bones while you are on an estrogen blocker. This is also something to consider if you already have weak bones. You would need to work with your doctor carefully to determine if the benefits outweigh the risks. 

Not all estrogen blockers will affect your body the same either. So, if one medication is causing you side effects, your doctor may suggest another formulation that may work better for you. 

Where To Get Estrogen Blockers

Estrogen blockers are a medication and therefore need to be prescribed by your doctor. Your primary care provider, family medicine doctor, endocrinologist, oncologist, or hormone replacement therapist are all able to prescribe you an estrogen blocker. They may prescribe you with an estrogen blocker after assessing your symptoms and doing some hormone level testing. 

After it is determined that an estrogen blocker is right for you they can give you a prescription for an aromatase inhibitor. With this you can fill the prescription at a local pharmacy. Another option is if you are working with a hormone replacement specialist like Elite HRT, where you can have your medications ordered through your online provider and delivered straight to your home. This makes it convenient because you do not have to make a second stop at the pharmacy and you do not have to worry about remembering to fill your refill. 


Estrogen blockers are important medications that can be very helpful in a wide variety of situations. Estrogen blockers prevent the process of aromatization where the testosterone in your body is converted to estrogen. This process can result in unwanted side effects, especially in men, with things like growth of breast tissue and an increase in abdominal fat. 

Having an unbalanced hormone level can be very frustrating from the symptoms as well as knowing your body is not functioning as it should. 

Our team at Elite HRT is ready to help you set up a personalized hormone replacement therapy plan just for you.


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