Aromasin aka Exemestane is an essential medication for your cycle. It’s an aromatase inhibitor that will help you keep your Test high and your Estrogen low (because this is how you get gains). Here's an in-depth look at the drug, its properties, uses, and potential side effects.


  • Drug class: Aromatase Inhibitor
  • Ative: 24-30 hours
  • Chemical type: Steroidal suicide aromatase inhibitor
  • Why you need it: to prevent excessive conversion of Testosterone into Estradiol

Aromasin and Estrogen Reduction

Simply put, exemestane lowers estrogen production in the body. 

To get more info on AI’s in general, read our guide to Aromatase Inhibitors and aromatising steroids. Here, we’ll focus on Aromasin alone.

Originally, it’s a breast cancer treatment compound. Yet, in the fitness community, Aromasin's properties offer several advantages:

Estrogen Reduction

Exemestane reportedly lowers estrogen by an average of 85% [1]. It helps in preventing estrogen-related side effects often caused by aromatizing steroids.

Other Benefits

Aromasin destroys aromatase, which lowers Test, and also raises testosterone levels [2].

At the same time, Aromasin might increase levels of insulin growth factor (IGF-1) [3]. The exact compound you get from HGH. 

Aromasin Dosing and Usage

Aromasin is one powerful drug, and you definitely don’t want to risk taking too much of it: 

  • Recommended starting dosage: Begin with 12.5mg once or twice per week.
  • Continue adjusting the dose upward accordingly until you reduce high E2 sides.

Peak Concentration

Exemestane reaches its highest levels in the blood 2 hours after taking a 25 mg pill [4]. This rapid onset is something you should factor in. It is notably shorter than that for non-steroidal inhibitors.


The active life of Aromasin ranges between 24 and 30 hours.

Taking one 25mg pill lowers estrogen in the body for a few days. The biggest drop is 2 to 3 days after taking the pill. This suppression persists for about 4 to 5 days.

Effective Dosing

Research has shown that 25 mg Is more than enough. Using only 25 milligrams of Exemestane works just as well as 50 milligrams. It helps lower estrogen, boost testosterone, and increase IGF levels. 

No need for higher doses: It's unnecessary to go higher than 25 mg ED.

Achieving Steady Plasma Levels

When deciding how much to take, remember that Aromasin needs about a week to work well in your body. 

However, it’s not a real problem: just start Exemestane a week prior to the moment you really need it.

Aromasin Toxicity and Side Effects

Aromasin has no significant drug toxicity at doses up to 600 milligrams per day. Most people can handle it without problems. We don't know the highest safe dose yet.

While generally mild, the negative side effects related to Exemestane use may include:

  • Gastrointestinal effects;
  • Hot flashes;
  • Nausea and fatigue;
  • Erectile dysfunction, though relatively rare.

In addition, it may or may not affect your lipids. The studies that we have are inconclusive and conflicting [5]. Still, consider it if you have reasons to be concerned about your lipid profile.

Conclusion: A Relatively Safe Choice

Aromasin is a safe aromatase inhibitor with mild side effects and high potency.

But, it's important to control your dosage. Low Estrogen has similar side effects as low Testosterone. Those are not the effects you need (including erection issues, mood swings, and limited performance).

Don’t take more than you’re supposed to, find your sweet spot and maintain balance.

Aromasin FAQ

What does Aromasin do to men?

Aromasin lowers estrogen levels in men and can increase testosterone levels. Bodybuilders and athletes often use it to control estrogen-related side effects.

Does Aromasin permanently block estrogen?

No, Aromasin does not permanently block estrogen. If you keep taking the medication, its effects will last. After you stop taking it, estrogen levels usually go back to normal.

Is Aromasin better than Arimidex?

Aromasin and Arimidex both work well to inhibit aromatase, so it's not fair to compare them. Instead, we can say that Aromasin is definitely a safer choice than Arimidex.

Does Aromasin lower estrogen?

Yes, it's the only function. Aromasin reduces estrogen by blocking the enzyme that makes it called aromatase. When blocked, aromatase can't convert anything. And since Aromasin is a suicide inhibitor, each enzyme it contacts has no chances to perform its functions.

Does Aromasin remove gyno?

Aromasin can reduce gynecomastia by controlling estrogen, but it can't cure existing gyno. Treatment for existing gyno often requires surgery or other medical interventions.

Is Aromasin liver toxic?

Aromasin is usually well-tolerated. It doesn't usually cause serious liver problems at normal doses.

Who should not take Aromasin?

Those allergic to Exemestane or who have certain health conditions should avoid it. Also, people with Estrogen issues. Mostly, though, it's OK for the majority of bodybuilders.

Is Aromasin bad for your heart?

We don't know how Aromasin affects heart health due to conflicting research. Monitoring and consultation with your doc is a MUST if you have reasons to worry about your heart.

Can Aromasin cause blood clots?

There's no strong evidence to suggest that Aromasin directly causes blood clots. Always discuss potential risks and side effects with your healthcare provider.