Letrozole (Femara) and Arimidex are the two most popular of the top three aromatase inhibitors, with Letrozole being the second most popular.

Letrozole has demonstrated remarkable efficiency in reducing estrogen, more so than the other two major aromatase inhibitors.

When compared to Arimidex, Letrozole has been found to be 10 to 20 times as strong as Arimidex, and while the dosage of Letrozole is the same as Aromasin, it works through a different pathway, making it highly effective in its own right[1].

However, the medical and clinical use of letrozole or any aromatase inhibitor by an athlete or bodybuilder using anabolic steroids is a little different, and that's why we're going to discuss the top questions every anabolic steroid user has: the proper letrozole dose for estrogen control, how to utilize letrozole doses, and the different ways in which letrozole doses can be used.

First, it's important to understand that letrozole is an aromatase inhibitor and has many applications in terms of estrogen control.

As an aromatase inhibitor, it has the ability to literally control all of the potential estrogenic side effects that anabolic steroid users are trying to avoid or eliminate.

The standard protocol (or general rule) for the use of all aromatase inhibitors should be the following

Avoid the use of aromatase inhibitors unless absolutely necessary.

If you must use an aromatase inhibitor, use it only when absolutely necessary and use the lowest dose possible, with the goal of controlling estrogen, not eliminating it.

This is very important and should be kept in mind by all readers considering the use of aromatase inhibitors.

The bottom line is that aromatase inhibitors, whether they are the three main AIs (Arimidex, Aromasin, Letrozole) or any other, can have negative effects on the body if used at unnecessary times or if the dose of Letrozole is too high.

Remember that aromatase inhibitors should always be used to control estrogen rather than eliminate it, as completely reducing all estrogen levels in the body can and does have harmful effects on the body.

This is discussed in more detail in the side effects section of this profile, but in general, these compounds (aromatase inhibitors) can be described as depriving the body of a very important hormone (estrogen) that is important for a variety of essential bodily functions at normal physiological levels.

Medical Letrozole Dosage

Letro is approved by the FDA as an adjuvant treatment for postmenopausal female breast cancer patients who have failed first-line treatments (such as Nolvadex).

It is also approved as an extension treatment for postmenopausal women with breast cancer 5 years after Nolvadex.

Letrozole is also approved for the treatment of postmenopausal women with breast cancer who have symptoms of estrogen receptor-unknown breast cancer.

This is a breast cancer condition in which the diagnosis does not indicate whether estrogen is the cause or whether the breast cancer has been made worse by estrogen.

Finally, it is also approved for the treatment of postmenopausal female breast cancer patients for whom all other anti-estrogenic compounds (including SERMs and all other AIs) have been ineffective.

Letrozole is often tried as a last resort and final treatment for breast cancer patients when all other treatments have failed.

The dose of letrozole for the treatment of breast cancer in all cases is 2.5 mg daily.

Letrozole dosage during anabolic steroid use

Notably, letrozole cannot be categorized into three user tiers (beginner, intermediate, and advanced) as is commonly described and listed in the common profiles of other compounds and drugs.

This is due to the fact that letrozole is not specifically used for performance enhancement purposes, but rather as an ancillary drug used to prevent or mitigate various estrogen-related side effects when using aromatizing anabolic steroids.

In some cases, letrozole may be used to increase endogenous testosterone secretion in men, and the compound may be used as an ancillary drug during the post cycle therapy (PCT) phase after the end of an anabolic steroid cycle, but its use alone for this purpose is uncommon and is unlikely to produce any noticeable performance enhancing effects.

The use of letrozole as an endogenous testosterone stimulant will be covered in more detail shortly.

For the purpose of estrogen control during a cycle:

Letrozole is the most effective aromatase inhibitor used to lower circulating estrogen levels in the body during cycles using aromatizable androgens (anabolic steroids that have an affinity to bind to the aromatase enzyme and aromatize into estrogen).

This was discussed earlier in the introduction.

The dosage of letrozole for this purpose is very broad, and how much letrozole is needed (and how often) is highly dependent on the dose of aromatizable anabolic steroid used, the individual's sensitivity to aromatase inhibitors, and the rate of aromatization of the anabolic steroid used.

Therefore, a typical dosage of letrozole is approximately 1.25 mg to 2.5 mg daily.

There is a great deal of room for adjustment when it comes to letrozole dosage and user preference, as each individual should slowly adjust their dosage based on how their body responds.

This is especially true for letrozole, the strongest and most potent AI of the three. For many anabolic steroid users, even 1.25mg daily is too much, and in fact, the recommended dosage is often 1.25mg every other day, and often even less, especially considering letrozole's half-life of 2-4 days.

These letrozole doses can be easily adjusted if the user feels they are not working well enough or if estrogen levels are decreasing too much.

Always remember that the purpose of using an aromatase inhibitor is not to completely reduce or eliminate estrogen levels and cause problems in the body, but to control estrogen levels and return them to normal physiological levels.

It is intended to reverse/eliminate gynecomastia:

Clinical data in rats and anecdotal evidence have shown that letrozole can actually reverse and eliminate the progression of gynecomastia.

This is one of the unique effects of letrozole.

Other aromatase inhibitors can have this effect, but if gynecomastia has progressed beyond a certain point, it is irreversible and must be surgically removed.

While letrozole does not have the ability to eliminate fully developed gynecomastia, it has demonstrated the ability to potentially reverse gynecomastia at a stage of development far beyond the reversibility of aromasin (Exemestane) or arimidex (Anastrozole).

Notably, studies in mice have shown that receptor overexpression (caused by estrogen) that induces breast changes is abolished by even low doses of letrozole [2].

Although these studies were conducted in mice, there are many anecdotal reports of patients with gynecomastia who have had all other treatment attempts fail and have effectively reduced and eliminated ongoing gynecomastia using letrozole in combination with a SERM (such as Nolvadex).

While reversal of gynecomastia is not guaranteed (especially as it depends on your situation), it is worth a try, especially if you are someone who has recently developed gynecomastia (the sooner you treat after developing gynecomastia, the better).

Female Letrozole Dosage

Female anabolic steroid users rarely have to worry about elevated estrogen levels, but competitive bodybuilders who need to eliminate estrogen-related water retention that causes unwanted bloating may need to use an aromatase inhibitor such as Letrozole (Femara).

However, due to the strong effects of letrozole, it is recommended that women try one of the other two major aromatase inhibitors first before using letrozole.

This is because it has been medically proven that aromatase inhibitors actually have a much greater effect on estrogen reduction in women than in men.

It's important to remember that medically, letrozole is only approved for use in postmenopausal women, whose hormone levels are very different from premenopausal women.

Among postmenopausal women with breast cancer, letrozole is used as an absolute last line of defense against breast cancer after all other treatments and medications have failed.

Because medical data shows that aromatase inhibitors are much more effective in women than in men (depending on the aromatase inhibitor used), a letrozole dose of 1.25 mg every other day or every two days is sufficient, and in fact, it is often too high a dose, in which case individuals may feel the need to adjust to a lower dose or fewer doses.

Letrozole dosage for increased endogenous testosterone secretion and post cycle therapy (PCT)

We have previously mentioned that letrozole has the potential to increase endogenous testosterone levels in men.

This is accomplished through a negative feedback loop in the hypothalamic-pituitary-testicular axis (HPTA), where excess estrogen in men can and has been found to suppress the production of endogenous testosterone, leading to hypogonadism.[3] In particular, studies have shown that letrozole has the potential to increase estrogen levels in men.

Letrozole, in particular, has been shown in many studies to increase testosterone levels through estrogen reduction.

One study concluded that when letrozole was administered to elderly men with sexual dysfunction due to decreased endogenous androgen production, testosterone levels returned to normal physiologic levels and sexual function was restored[4].

The study found that LH (luteinizing hormone) and FSH (follicle stimulating hormone) increased, while SHBG (sex hormone binding globulin) decreased.

LH and FSH are two important gonadotropins that signal the testes to start producing testosterone, and SHBG is a protein that binds to androgens and inactivates them (in much the same way that aromatase inhibitors bind to and inactivate the aromatase enzyme).

In the same study, Letrozole was found to be so effective at reducing estrogen in men that the test subjects' estrogen levels were virtually undetectable.

Based on the data provided, it is easy to conclude that Letrozole will be effective in providing the testosterone boost needed in the weeks following discontinuation of anabolic steroid use.

There is one problem with adding Letrozole to a PCT program that includes the use of SERMs such as Nolvadex and Clomid, which are known to be absolutely essential components of a PCT program.

This same issue is evident with Arimidex, but not with Aromasin (Exemestane).

The problem is that letrozole and nolvadex (Arimidex and Nolvadex) directly cancel each other out.

One study showed that when Letrozole and Nolvadex are used together, Nolvadex decreases the plasma concentration of Letrozole (and Arimidex, another commonly used aromatase inhibitor) [5].

The bottom line is that it is a very bad idea to use Letrozole and Nolvadex together.

Therefore, if Letrozole is used with Nolvadex, its use as a PCT ingredient is very limited.

Instead, it may be more beneficial to stack it with HCG, but it suffers from the lack of an essential ingredient in a SERM aimed at stimulating endogenous testosterone.

Therefore, a better aromatase inhibitor for PCT instead of Arimidex would be Aromasin (Exemestane), as unlike Letrozole, Aromasin has been shown in studies to not have its effects removed or reduced by Nolvadex [6].

The right dose of letrozole and when to take it

There are no special considerations when taking letrozole, and it can be taken at any time of day (morning, evening, before, during, or after meals).

One important thing to keep in mind when taking letrozole is that although the half-life of letrozole is approximately 2-4 days[7], it actually takes 60 days for plasma blood levels to reach optimal peak levels.

Letrozole has the longest time required to reach optimal peak plasma blood levels of the three aromatase inhibitors (in contrast, Arimidex and Aromasin take 7 days to reach optimal peak plasma levels).

Expected effects and consequences of taking letrozole

Since Letrozole is the most effective aromatase inhibitor at lowering estrogen levels to undetectable levels, users should be careful not to let their estrogen levels get too low to be considered healthy.

Lowered estrogen levels can cause the physique to appear harder and more 'ripped' due to the loss of water retention provided by estrogen.

This results in little to no subcutaneous fat, making muscles appear more prominent.

One exception to the problem of completely eliminating estrogen is in the case of competitive bodybuilders who need to almost completely eliminate water retention on competition days.

In this situation, Letrozole may be the best aromatase inhibitor over all other aromatase inhibitors used at full doses by competitive athletes days before a competition for the aforementioned physique changes.

The almost total reduction of estrogen should not be maintained for more than 48 hours for health reasons.

Medical references

[1] Pharmacology and pharmacokinetics of the new generation of aromatase inhibitors. Buzdar AU. 2003 Jan;9(1 Pt 2):468S-72S.

[2] A transgenic mouse model of aromatase overexpression: cell type-specific expression and use of letrozole to abolish mammary hyperplasia without affecting normal physiology. Mandava U, Kirma N, Tekmal RR. 2001 Dec;79(1-5):27-34.

[3] “The dangers of excess estrogen in aging men”. Faloon, William. Life Extension Magazine, November 2008.

[4] Aromatase Inhibition, Testosterone, and Seizures. Harden C, McLuskey NJ. Epilepsy Behav. 2004 Apr;5(2):260-3.

[5] Comparative clinical pharmacology and pharmacokinetic interactions of aromatase inhibitors. 2001 Dec;79(1-5):85-91, Boeddinghaus IM, Dowsett M. J Steroid Biochem Mol Biol.

[6] Inhibitory effects of combined treatment with the aromatase inhibitors exemestane and tamoxifen on DMBA-induced mammary tumors in rats.

[7] Pharmacology and pharmacokinetics of the new generation of aromatase inhibitors. Buzdar AU. 2003 Jan;9(1 Pt 2):468S-72S.