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How do I take Arimidex on a cycle and how much?

Medically reviewed by Carmen Pope, BPharm. Last updated on May 17, 2023.

Official answer

  • When used to treat or prevent hormone receptor-positive breast cancer in postmenopausal women, Arimidex is usually taken once a day.
  • Illegally, Arimidex may be used by bodybuilders to block estrogen.
  • Arimidex may help prevent side effects such as gynecomastia (male breast enlargement) from developing due to the aromatization of anabolic steroids.
  • When used for this purpose, Arimidex is typically introduced in week two of the cycle and taken for the entire length of the cycle at 0.5mg twice a week.
  • Arimidex is only approved by the Food and Drug Administration (FDA) for use in breast cancer treatment. Taking Arimidex for bodybuilding is not recommended and many high estrogen side effects of anabolic steroids go away once they are stopped.

Arimidex (anastrozole) is a medication that is used to treat hormone receptor-positive breast cancer in postmenopausal women. In most cases, Arimidex is taken daily for five years, although some women may take it for a shorter period. Arimidex is usually taken in addition to other medications.

Arimidex may also be used illegally by bodybuilders to reduce side effects caused by high estrogen levels that occur from the aromatization of anabolic steroids. The usual dosage is 0.5mg twice a week starting from week two of the anabolic steroid cycle.

The Food and Drug Administration (FDA) has only approved Arimidex for use in cancer treatment. There are no formal guidelines for its use in bodybuilding.

What is aromatization?

Aromatization is a natural process and it is a way to keep testosterone and estrogen in balance.

Even though testosterone is referred to as the male hormone and estrogen is referred to as a female hormone, this is not entirely correct as both are present in male and female bodies.

Although testosterone is the most significant hormone for male sexual development and function, a particular form of estrogen, called estradiol, is crucial to male sexuality. If estradiol is not in balance with testosterone, problems will start to be noticed with sex drive, the ability to have an erection, and the production of sperm. High estrogen levels in males also increase your risk of other conditions such as diabetes and cancer.

Naturally in males, testosterone levels decline with age, and estrogen levels increase. When large fluctuations of testosterone production occur, such as when anabolic steroids are injected, this creates an imbalance of hormones in the body, and aromatization will occur in an attempt to balance the new testosterone with a higher amount of estrogen.

What are normal estrogen levels in men?

There are two main forms of estrogen present in adult males, estradiol and estrone. These are often undetectable in prepubescent and pubescent males (although can be as high as 60 picogram/mL [estrone] or 40 picogram/mL [estradiol]). In adult males, normal values are as follows:

  • Estrone: 10-60 picogram/mL
  • Estradiol: 10-40 picogram/mL.

For bodybuilders, estradiol levels of between 20-30 picogram/ml are desired.

What are the symptoms of high estrogen levels in men?

Symptoms of high estrogen levels in men include:

  • Decreased muscle mass
  • Difficulty focusing
  • Erectile dysfunction
  • Fluid retention
  • Gynecomastia (more breast tissue develops than normal leading to breast enlargement)
  • Hair loss
  • Hot flashes
  • Infertility
  • Osteoporosis (reduced bone density)
  • Reduced sex drive and sperm count
  • Slowed growth and short stature
  • Tiredness.

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