Letros (active agent – letrozole) is an oral non-steroidal aromatase inhibitor. In bodybuilding letrozol is used by males to reduce estradiol levels in blood by eliminating the production of estradiol through binding to and disabling the aromatase enzyme, which is responsible for the conversion (or aromatization) of androgens into estradiol.

Letros is the strongest and most potent of the three most popular aromatase inhibitors by far. Only one standard tablet dose of 2.5mg is effective enough to reduce circulating estrogen levels by up to 98%.

In some cases, letrozole can be used as a treatment for gynecomastia, although it is probably most effective at this if caught in an early stage.

Letrozole also carries the ability to increase natural testosterone production through an increase of the luteinizing hormone (LH) and the follicle stimulating hormone (FSH), but this is normally not the preferred method of treatment.

Warning: Do not exceed recommended dosages! For bodybuilding purposes as aromatase inhibitor even with the use of anabolic steroids, a 2.5mg dosing will normally be too high and could potentially drain the individual of energy; in fact, it’s almost guaranteed. For standard estrogenic related protection 0.5-1 mg every other day will be more than enough.

• Chemical name4-[(4-cyanophenyl)-(1,2,4-triazol-1-yl)methyl]benzonitrile
• FormulaC17H11N5
• Anabolic activity indexnot a steroid
• Androgenic activity indexnot a steroid