Letrozole Doubles Mens Testosterone Levels

Letrozole Doubles Mens Testosterone Levels

Blog Entry #48

By Admin – Steroidal.com

Letrozole, or also commonly referred to as Femera, is an anti-estrogen. To be more precise it’s actually an aromatase inhibitor (AI) and lowers estrogen levels by binding to the aromatase enzyme. Estrogen is produced in men mainly by the skin and adipose tissue, but also by the adrenals, liver, mammary glands, hair and in the male gonads. Estrogen levels are important in men and are used for a variety of functions in the body. These include, bone density, lipid metabolism, growth and sexual maturation.  Unfortuneatly, its not all good and when estrogen is left to climb side effects can arise some of these are; water retention, gynecomastia, acne, cholesterol problems, cardiovascular issues, loss of sex drive, energy, prostate issues, cardiovascular problems, cancers and aggression or mood swings. These side effects can be apparent during puberty, but also when testosterone based anabolic steroids are used as they can aromatase and push estrogen up. Which is why AIs are used to ward off these nasty side effects, some permanent. AI use has risen in recent years because these side effects are more understood and AIs have been more widely available now often sold for “research”.

A compound that blocks estrogen, much like a selective estrogen receptor modulator (SERM), or lowers circulating estrogen levels has the ability to raise natural levels of testosterone. These work by different mechanisms, but essentially anything anti-estrogenic can raise total testosterone in healthy men. A SERM does this by blocking the estrogen receptor in the hypothalamus and an AIs mode of action is changing the androgen:estrogen ratio. The human body is a fantastic and clever biological machine, and when it senses a low estrogen level, it compensates by increasing testosterone output to balance testosterone and estrogen. But how much can it raise natural testosterone levels?

In 2010 Urologists at the University of Mersin in Turkey, conducted a study on 27 infertile men [1]. The men were given the 2.5mg for six months, half of which suffered from Azospermia (no sperm).

The figure below shows that the men given 2.5mg every day of Letro had doubled their testosterone levels in six months. Estrogen levels also fell 45%. In another study done in Canada in 2009, Letro again doubled a male subject’s testosterone levels [2].







On many steroid and bodybuilding forums across the internet you’ll see Letrozole dosages far lower advised. Although this is mostly based on “bro-science” 2.5mg per day of Letro will not lower you estrogen levels by 90-95%. The effectiveness of Letrozole is less in men, then women, and can also change again in elderly patients. If you want to raise testosterone levels by this above method, we’d first suggest you explore using SERMs, various over the counter herbal products, such as Fenugreek, Tongkat Ali and Ginger and not begin Letro self treatment at 2.5mg per day. At this dosage, you can cause sexual side effects and cause serious cholesterol issues. Letro has a long active life, so we’d recommend starting on 2.5mg every 4-5 days and get testosterone levels checked by a physician after 3-4 weeks of use.


[1]. Fertil Steril. 2010 Oct 8. [Epub ahead of print]

[2]. Fertil Steril. 2009 Aug;92(2)