Aromatase inhibitors

Aromatase inhibitors – drugs used to lower the amount of estrogen in the blood and increase the concentration of testosterone. In sports, aromatase blockers are mainly used during the AS program, performing the following tasks:

  • promote the accelerated recovery of hormonal system during the use of AS;
  • prevention of gynecomastia;
  • increasing the amount of gonadotropin.

Aromatase blockers

Do not forget that estradiol is necessary for the normal functioning of the body, that is why athletes need to monitor its concentration in the blood, especially during AS programs. It is worth noting that a moderate amount of estrogens is useful for muscle growth. Aromatase inhibitors help to keep normal level, to balance the hormonal system.

Please note that during the taking AI, it is necessary to systematically monitor the concentration of estrogens in the blood, because in case of an excessive drop in the level of this hormone, muscle and bone tissues are destroying, the nervous and cardiovascular systems suffering. These processes can be accompanied by mood swings, insomnia, memory impairment, depression, falling libido, joint pain and other unpleasant side effects.

Attention! Aromatase inhibitors are not used on PCT, it is advisable to use them only during the program and after the end of the AS program (before PCT). During post-program therapy estrogen receptor blockers (Tamoxifen, Clomid) are used.

Aromatase inhibitors drugs

Ones of the most popular AI are Anastrozole, Letrozole and Exemestane. They can be purchased at the pharmacy. Separately should be mentioned Proviron, which is a weak blocker of aromatase.

Anastrozole is the leader among the above mentioned drugs. It works effectively by lowering estrogen levels in the blood, and it is well tolerated by the body. It is worth noting that Anastrozole is available in tablet form at a dosage of 1 mg. In sport, for preventive purposes, athletes use this drug in a dosage of 0.5 mg a day, and in case symptoms of gynecomastia 1 mg until a day of their disappearance. Then it is necessary to lower the dosage to 0.5 mg a day. Anastrozole should preferably be taken after meals, drinking plenty of water.

Letrozole and Exemestane are also highly effective drugs. Besides, their cost is much lower than Anastrozole. Their drawbacks are quite strongly inhibiting estrogen levels (as you remember, an excessive drop in estrogen levels is fraught with unpleasant consequences), that is why the action of these drugs is hard to control. Besides, it is necessary to note that letrozole is manufactured tableted dosage at 2.5 mg per tablet. Preventive dose is 0.5 mg. For the prevention it is necessary to divide the pill into 5 equal parts, which is extremely inconvenient.

Intake of aromatase inhibitors

As you already know, aromatase blockers are not used during PCT. They should be used during the program of anabolic steroids. However, when it is necessary to start taking aromatase inhibitors? In the world of sports there are many tactics of its taking. The most popular of them:

  • start taking 2 weeks after the start of the program;
  • start taking from the moment of manifestation of the first signs of gynecomastia;
  • after 2-4 weeks (2 for drugs with a short half-life, 4 with a long one) carry out tests for the amount of estrogens in the blood. If their level is not satisfactory, you should to start taking a preventive dosage of AI. After 2 weeks after the beginning of the use of AI, you need to carry out a control analysis on the number of estrogens. And depending on the results further dosage should be corrected.

The last (3rd) option is recognized as the most optimal. However, due to the fact that it is the most expensive both in time and in finance, many athletes neglect the delivery of tests, which is the wrong approach and ultimately can have a negative impact on the health of the athlete.

The website of provides information only for informational purposes. "IronSet" does not sell and does not call for use of potent substances, including anabolic steroids. This information is collected from public sources and can not serve as a basis for deciding on the use of certain drugs. The information presented on the website does not call for the use or distribution of potent substances.


Andrey is a coach, sports writer and editor. He is mainly involved in weightlifting. He also edits and writes articles for the IronSet blog where he shares his experiences. Andrey knows everything from warm-up to hard workout.

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