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Letrozole (Femara)

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Letrozole (trade name Femara) is an oral aromatase inhibitor (AI) used in the treatment of hormonally responsive breast cancer after surgery. The FDA approved its use in post menopausal women who show hormone receptor positive types of breast cancer. It was banned in India in 2011 due to potential risk to infants when used in women who are pregnant; however, a Canadian study done by the American Society of Reproductive Medicine showed no evidence of birth defects. As a result, it remains legal in the rest of the world.

Table of Contents

Off-Label Use

Letrozole (letro) has many uses which have recently been discovered. Aside from its female breast cancer use (typical of all AI's), letro has off-label uses in medicine. Since 2001, the main off label usage has been as a fertility drug because of its ability to stimulate ovaries. Another use, because of its strong anti-estrogen properties, is to use in a stack with misoprostal for early pregnancy termination. It also has off label use as a treatment for gynecomastia, and it's used in a stack with growth hormone to help adolescent boys grow taller. It even promotes spermatogenesis in male patients (boosting sperm count). Femara is fairly inexpensive, which makes it a unique and versatile drug.

How does it work?

Similar to all aromatase inhibitors (AIs), letrozole, by binding to the aromatase enzyme, prevents estrogen from being released. It is known as a type II aromatase inhibitor.

It is the most powerful AI available; in fact, studies have shown it to drops estrogen levels in women by up to 98%. In men, clinical studies have shown a drastic reduction in estrogen levels very quickly of up to 65%. The main reason may be because it has the ability to crush estrogen through competitive/reversible binding to the heme of the relevant cytochrome P450 unit (protein enzyme).

Use in Bodybuilding

Since letrozole is such a powerful AI, it can be a great weapon to combat emergency situations, where estrogen related sides get out of control. When an anabolic steroid user uses compound such as testosterone, dianabol, deca durabolin, equipoise etc; they will aromatize in the body and convert to estrogen. This can result in multiple estrogen side effects such as water retention, which has a domino effect and can effect your libido, sleep, blood pressure, and energy. Another dangerous estrogen side effect is gynecomastia (bitch tits), which, if left untreated, can require expensive and invasive surgery. For this reason, it is crucial to run an aromatase inhibitor if you use aromatizing steroids during your cycle.

Gynecomastia Treatment

As I said earlier in the article, letro is perhaps the most powerful AI in the world, as it has been shown in studies to reduce estrogen levels quickly and sharply. Many users have commented on how effective letro was to stamp out their gyno while on cycle, when other AI's just weren't strong enough.

If a user neglects to use an AI from day 1 of a cycle and finds themselves in desperate shape, they can turn to letro as a quick gynecomastia cure. In fact, in a recent study on rodents letrozole destroyed breast tissue tumors, which gives a glimpse how effective it can be in treating human gynecomastia.

When it comes to treating bitch tits (gyno), there is nothing that's more effective than letrozole. Literally, nothing. That's why letro is part of every anti-gynecomastia cure stack in bodybuilding. It's the only AI that can save you from surgery!

Letrozole vs. Aromasin-Arimidex

Letrozole is not a suicide aromatase inhibitor, meaning it will not permanently disable the aromatase enzyme, so it is not the same as aromasin. The other difference is letro is far more powerful at crushing estrogen levels than either aromasin or arimidex. I would use it in emergency situations over the others, but I wouldn't abuse it.

Negative Side Effects

There is such a thing as too much in the bodybuilding world, and, when it comes to AI's, letrozole definitely fits that bill. Although, as males, we view estrogen as a female hormone, that does not mean we don't need it in our system to properly function. After all, estrogen helps males grow muscles! Low estrogen can cause depression, effect mood, hurt the immune system and lower libido. Since letro is so powerful at dropping estrogen levels, you must be careful not to abuse this drug. You should always keep it on hand for emergencies; in fact, always have it on hand before running a cycle. View it as a rainy day fund. When the gyno tits hit the fan, it might be too late, so don't risk it guys.

Dosages and Half Life

The half life is approximately 2-4 days. Dosages vary quite a bit, 0.25mg up to 1mg every day or every other day is a good starting dose. It's best to be conservative with the dosage because if you overdose the sides can be harsh.


Informational Video:


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Geneza GP Letrozole

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Accord Letrozole


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Written by
Steve Smi (Also known as Steve Smith), has over 12 years of experience in the bodybuilding and fitness industry. He's the co-Host of the popular Evolutionary Radio Podcast - over 500,000 listens! He has been a personal trainer and writer for the last 10 years with over 1000 articles written. He's been a moderator on forums for over 10 years. Steve holds the following certifications and records: NASM Personal Trainer NASM Fitness Nutrition Specialist Florida Local Powerlifting champion Top writer for 2019 Fitness rated

1 Comment

  1. Avatar photo

    Hello there,

    I have bitch tits since high school. Not too much but noticable with white t-shirts.
    I workout a lot , i have a decent healthy body.
    I am wondering to try femara but i wanna ask if it has any complications with cipralex dosage 10mg

    thank u

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