Trade name: Arimidex

Anastrazole and male infertility

Anastrazole is an aromatase inhibitor. Aromatase is an enzyme located in the testicles, fat cells, and the liver that converts part of the testosterone in the bloodstream to estradiol. Anastrazole decreases the action of aromatase, which results in higher testosterone levels and lower estradiol levels. Anastrazole can also raise FSH and LH levels.

A common misconception is that mildly increased estradiol levels play a negative role in men’s health, and specifically that it decreases libido and sexual function. Actually, maintaining adequate estradiol appears to play several important roles in maintaining good sexual health, as recent studies have also shown that very low levels of estradiol can lead to an increased risk of low libido and sexual problems in men. The clearest role of estradiol seems to be in maintaining normal bone health (along with testosterone). When estradiol levels are low (under 20 pg/mL) over extended periods of time, there may be an increased risk of developing osteoporosis (for more information, see the “Osteoporosis” section of this website).

Short-term use of anastrazole (up to a few years) with proper monitoring and prevention strategies is typically fine in most men, but prolonged use may increase the risk of fractures.

High levels of estradiol can potentially decrease sperm production and sperm quality. Another issue is that prolonged elevation of estradiol can also lead to gynecomastia (abnormal breast development in men).


How Anastrazole Is Used

Anastrazole comes in 1 mg tablets. The typical starting dosage in men is 1 mg per day (although some clinicians have begun to use smaller doses, such as 0.25 mg daily; the smaller-dose tablets must be made by specialty compounding pharmacies). I usually recommend follow-up testing two weeks after starting anastrazole, or two weeks after any change in dosage or medications. Dosages can then be adjusted depending on the findings of the follow-up blood hormone tests.


Here is a sample range of dosages:

•          1 mg every third day

•          1 mg every other day

•          1 mg every day (typical starting dosage)


It is generally not recommended to take more than 1 mg daily because of the potential risk of liver toxicity.


Cost of Anastrazole

Anastrazole may be covered by your insurance company.  However, if you do not have insurance coverage for your medications, the price of anastrazole at some regional and fertility-specific pharmacies is reviewed in the "Fertility Medications Cost" section of this website.


Side Effects

Similar to clomiphene, most men taking anastrazole either do not have any adverse side effects at all, and may even feel better because of the higher testosterone level.

However, some uncommon adverse side effects can occur, including:

     1) Increased blood pressure

      2) Rash

      3) Paresthesias (sensations of skin tingling, pricking, or burning)

      4) Malaise

      5) Peripheral edema

      6) Glossitis (inflammation or swelling of the tongue)

      7) Anorexia (lack of appetite)

      8) Alopecia (hair loss; usually resolves spontaneously when the medication is discontinued)

      9) Decreased libido

      10) Erectile dysfunction (2 percent of men)

       11) Acne (due to increased skin gland oil production; usually subsides after a few months of treatment)


If you experience significant negative side effects, it is best to stop the medication and contact your doctor for further guidance.