The US FDA approved letrozole as a prescription drug in 1997. Since then it has been sold by the pharmaceutical company Novartis under Femara trade name. Novartis expanded the trade over more than 70 countries, which approved the drug as well. Today, Femara takes predominant position in the global market.

Chemical Structure

Letrozole (FEMARA®) is a nonspecific competitive aromatase inhibitor. By its chemical structure letrozole is a nonsteroidal triazole derivative 4, 4'-[(1H-1,`2, 4-triazol-1-yl)-methylene] –  bis-benzonitrile. Its structure and mechanism of action are very similar to the ones of Arimidex, which is used in the USA for the same purpose.

Athletes and bodybuilders use letrozole to prevent estrogenic side effects, such as gynecomastia, obesity, overhydration. Letrozole is one of the latest drugs in a great range of aromatase inhibitors. It works more effectively and selectively than first-generation drugs, such as Teslac and Cytadren.


  • It is used along with a course of steroids to reduce estrogen level and to slightly boost testosterone.
  • It is considered one of the best drugs in this domain, that’s why letrozole is quite popular among bodybuilders.
  • The drug can reduce estrogen concentration by 97 %.
  • Low estrogen level means fewer side effects during the course, which is very important for athletes.
  • In bodybuilding letrozole enhances the production of certain hormones (luteinizing hormone, follicle-stimulating hormone, globulin), which, in turn, increase testosterone production.


  • Prevention of side effects caused by estrogen (water retention, acne, fat depot, gynecomastia).
  • Elimination of gynecomastia early in the course.
  • The product helps to maintain muscle tissue after anti-catabolic treatment. (In bodybuilding there is a widespread notion, such as catabolic failure, which occurs after taking steroids).

Letrozole would be very appropriate if taken in the course along with anabolic steroids and androgens.

Side effects

Possible side effects include:

  • headache;
  • joint pain;
  • fever;
  • fatigue;
  • nausea;
  • high blood pressure;
  • dizziness;
  • hair loss.

It should be noted that side effects can be caused by overdose only. To avoid such reactions, stick to the recommendations for use.

Dosages and Uses

In bodybuilding the recommended dose of letrozole is 1-3 mg per day (can be taken at any time of a day). Studies revealed that daily dose of even 100 mcg inhibits aromatase enzyme quite effectively. Overdose can lead to the problem of decreased libido. 

Daily dose for every athlete is different, depending on age, experience and the length of course. However, it should remain within the range of 1-3 mg per day.

Cycles (Courses)

You can check your individual dose with a specialist. Before taking any drugs, you should better consult with your doctor.

After a long course of letrozole you can switch to a different scheme, taking the drug on alternate days instead of every day.

In bodybuilding letrozole can be used by almost everybody. There are no special contraindications. However, those athletes with intolerance to any ingredient of the product or liver problems are recommended to take letrozole under the care of a physician. In case you feel bad during the course, you should better replace the drug with some other one, which would be more appropriate.

If you develop gynecomastia, take 2.5 mg of letrozole every day until the symptoms are relieved. After that, reduce the dosage to the preventative 0.5 mg every other day.