Arimidex (Adex) Explained


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Arimidex is a prescription grade drug designed for post menopausal women to lower estrogen levels in relation to cancerous tumors, primarily breast cancer. As the tumors grow larger they require estrogen to grow therefore Arimidex can be prescribed to lower estrogen levels during these circumstances. For short, Adex, is an aromatize inhibitor just like its brother aromasin, but with a few slight differences.

Mechanism of Action

In the bodybuilding world one generally uses adex to control estrogen levels when taking anabolic steroids. It works primarily by inhibiting the synthesis of estrogen, not destroying it. Adex binds reversibly to the aromatize enzyme so that estrogen cannot bind and therefore keeps estrogen levels from rising.


When on an anabolic steroid cycle and using aromatizing compounds such as testosterone, dianabol, and deca-durabolin to name a few, estrogen levels will rise in the body via the binding of the aromatize enzyme. Hence the name: aromatize inhibitor, a user does not want estrogen to bind and increase in the body, which is why we use compounds such as adex when running an anabolic steroid cycle. High estrogen levels can lead to a list of serious side effects for males when cycling; therefore it is imperative to incorporate compounds such as adex on cycle.

When experiencing gynecomastia (enlargement of male breast tissue) like symptoms, many will resort to the use of adex and or increasing their current dosage of it. Although this might temporary lower estrogen levels especially in the breast tissue, there are better alternatives for this estrogenic side effect. A stronger suicidal AI such as aromasin or letrozole would much better suffice coupled with the use of nolvadex, a selective estrogen receptor modulator.



When dosing an aromatize inhibitor there is no one size fits all, it’s a trial and error process with numerous variables just like anything in the bodybuilding world. The general guideline when using adex on cycle is .5mg every other day due to the longer half life it possesses, about 45 hours.  For those a little more prone to estrogenic side effects, 1mg EoD (every other day) can be a suitable starting point.



After 24 hours of administrating 1mg of arimidex, estradiol (estrogen) levels can be reduced up to 70% and up to 80% after 10-14 days.  Although adex has a long half life it enters the bloodstream and begins to work within a matter of hours and is generally well tolerated by the intestinal tract.

As a prescription drug Anastrozole is FDA approved for the treatment of breast cancer in post menopausal women and is being research in other types of cancer remedies. Thousands of clinical studies have been done requiring the certified FDA approval in the medical industry.


Choosing an Aromatize Inhibitor

The three most popular aromatize inhibitors used today are: Adex, aromasin, and letrozole. As a beginner to the AAS world the choice usually comes down to adex vs. aromasin, where letro is excluded because it’s for advanced users in certain scenarios.

Adex was the most popular AI over the last 20 years or so which is why it is recommended from “vets” to “noobs” in the AAS community. However, aromasin has made itself extremely popular over the last decade because it not only blocks estrogen but destroys it, meaning aromasin is a suicidal AI while adex simply blocks the aromatize enzyme.

So what is the right choice between adex and aromasin? There is no clear cut winner here because they are both very good at controlling estrogen levels on cycle. Everyone responds differently to nearly every compound just like with diet and training; it really comes down to a trial and error process to know and understand how you respond and feel. It is an absolute must to get blood work taken pre, mid, and post cycle to make sure everything is in check, especially estrogen levels mid cycle. From here is where a user can adjust their given AI dosages.

Side Effects

Side effects when using adex is typically mild for most, but there is always a chance of some side effects from user to user.

-Negative impact on cholesterol

-Mood swings and depression

-Joint pain / stiffness

-Blurred vision

-Loss of libido

-Hot flashes / headaches

-Bone mass decrease / low estrogen sides

-Lower back pain

-Loss of energy


Things to consider

Since adex only inhibits the conversion of estrogen, once use is discontinued there is a chance estrogen levels can begin to rise again. This is why it’s recommended to use adex from day 1 of your anabolic steroid cycle all the way up until post cycle therapy.

It is essential to get blood work done to make sure estrogen and other hormones and enzymes in the body are in check. Ultimately it will always come down to the individual on what products work best for them and in what dosages and protocols. Nonetheless, adex has been proven to be a very useful and effective aromatize inhibitor for those considering an anabolic steroid cycle.



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