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Letrozole (Femara) PCT 101: The Bodybuilder’s Guide

Discover the benefits and side effects of using Letrozole (Femara) for PCT, including dosing recommendations, buying options, and more.
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Disclaimer: The following guide is based on my personal experience and does NOT promote the illegal use of PEDs.

If you thought all aromatase inhibitors were created equal, Letrozole would have you thinking again! Yes, all AIs work similarly in their primary action, but no other AI is quite like Letrozole.

So, what is it that makes Letrozole so feared in the bodybuilding world? Is this AI really one you should be using at all? And how does it compare to our other aromatase inhibitor options? I’m here to reveal everything about Letrozole that’s relevant to us as bodybuilders.

Buckle up and dive in!

What is Letrozole?

Letrozole is a non-steroidal aromatase inhibitor (AI). Femara is the most well-known brand name that Letrozole is sold under worldwide.

Letrozole Aromatase Inhibitor
Letrozole Aromatase Inhibitor

Out of all the AIs, this would have to be the least used among steroid-using bodybuilders to control estrogenic side effects. It’s an AI with a reputation for being unpleasant to use for us guys – and for some good reasons.

History and Overview

Like most AIs, Letrozole’s primary purpose is to be used as a medical treatment for breast cancer in postmenopausal women following traditional cancer treatments like radiation or after a 5-year treatment of Nolvadex.

This AI didn’t get its medical approval by the FDA until 1996, despite being developed in the 1980s. The only FDA approval it currently has is for breast cancer treatment. But like many medicines, Letrozole is also sometimes prescribed off-label for other conditions, including:

  • Gynecomastia in males
  • Female infertility
  • Endometriosis

With studies finding that Letrozole is the only aromatase inhibitor with the ability to be more effective when used as a pre-surgical early breast cancer treatment (even more so than Nolvadex), some countries have approved Letro for this specific use[1]. This fact gives us a good idea of how powerful Letrozole is compared to other AIs.

Mechanism of Action

Letrozole decreases the level of estrogen in the body. In terms of its medical use, this is critical in halting the growth and spread of breast cancer tumors, which can be stimulated by estrogen.

As a non-steroidal AI, it has some benefits over older types of aromatase inhibitors because its actions won’t affect other hormones like:

  • Cortisol
  • Thyroxine
  • Aldosterone

At its core, Letrozole’s most important mechanism of action is to act as an inhibitor to stop androgens from being converted into estrogen. It does this by binding (reversibly) to the aromatase enzyme. This makes it what’s known as a “non-suicidal AI.” And it’s this action that appeals to any male using anabolic steroids, which are capable of aromatizing.

Effects of Letrozole (Benefits) for Men

Letrozole’s benefits for men will revolve around estrogen control. Suppose you’re using aromatizing steroids (like testosterone) at higher doses. In that case, it’s very likely you’re going to suffer from problems of high estrogen, and these are both physical AND mental side effects.

Men will see a notable improvement in both physical and mental health when they get their estrogen under control with careful use of Letrozole. Here are the main benefits of using this AI:

Gynecomastia Control

Reversing gyno is the number one reason you will want to use Letrozole. You might have tried and failed with one or more other anti-gyno ancillaries with no success.

Letro is not likely to reverse your gynecomastia if you’ve been suffering the symptoms for a period of years. It’s primarily useful for immediate gyno control once you start noticing those early signs of:

  • Nipple tingling
  • Puffiness
  • A small lump developing

Letrozole should be started if these signs appear and then stopped once you’ve successfully reversed the gyno symptoms.

Mental and Sexual Health

Although not talked about as much as gyno, if you’ve let your estrogen get too high, you’re at high risk of severe libido issues, erectile dysfunction, and poor mood, including depression and brain fog. Simply rebalancing your estrogen can have you feeling like a different person – but you’ll need to get your Letro dosage on point to prevent an estrogen crash.

What are Aromatase Inhibitors (AI)?

Aromatase inhibitors are one of the two classes of drugs that are the most critical ancillaries for anabolic steroid users (the other being SERMs). However, AIs were not developed for the benefit or use of male bodybuilders.

These are essentially anti-estrogen drugs that have been developed as a medication for female breast cancer sufferers – importantly, AIs are for women who are post-menopause because the activity of an AI is to reduce estrogen levels drastically. As post-menopausal women no longer produce estrogen from the ovaries, AIs are typically only utilized in these older women.

The most essential things to know about aromatase inhibitors as they relate to our needs are:

  • AIs block the enzyme aromatase, which prevents the aromatization (conversion) of androgens (testosterone) into estrogen
  • AIs can help prevent and/or reverse estrogenic AAS side effects, including gynecomastia and water retention
  • Some AIs can stimulate the release of luteinizing hormone and follicle-stimulating hormone to promote testosterone production

AIs are possibly the safest and most well-researched drugs that we can ever use as gear users, thanks to the extensive amount of clinical study they’ve undergone over decades.

And the good news?

A little goes a long way with an AI. You generally only need a low dose and use it for a short period of time to get what you need out of it. However, one common newbie assumption that must be put to rest is this: Every AI differs from the next. They are not created equal, and you will tolerate some MUCH better than others. Some AIs are also better at addressing specific estrogenic symptoms than others. Letrozole is one AI that is considered the toughest to use and least tolerable for just about anyone.

Letrozole for PCT

Even though Letrozole has been shown to increase follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in female patients, this is not an AI we would typically want to use for post-cycle therapy. There’s only one AI that I’d consider for PCT, and that’s Aromasin – otherwise, SERMs are always going to give you the best results.


Medical use of Letrozole for women usually is 2.5mg per day. This would be at the high end of the dosage spectrum for us men using Letro on-cycle. As I want to keep making clear, Letrozole really is an extreme AI in terms of its adverse effects.

What does this mean?

It means firstly taking a low dosage, and I mean really low – you want to evaluate your response to this AI in the first few days. Also, you won’t necessarily need to take a higher dose because it’s often very effective at a minimal dosage for gyno reversal. Here’s what I recommend:

Letrozole Dosage On-cycle

Letrozole is going to be a very harsh ancillary to use on-cycle. Rarely would anyone want to use it as the primary anti-estrogenic because of its potency. Instead, Letrozole is best utilized specifically for gyno reversal.

A very low dose can still crush your estrogen levels and have you feeling horrendous! But if you’re not able to control your gyno symptoms with other more tolerable AIs and/or SERMs, then I recommend this: A VERY LOW dose of Letro, at least to start with.

  • Many guys will start as low as 0.5mg or even just 0.25mg daily. This dosage can be all you need to reverse early gyno.
  • 1.25mg per day can be enough to get rid of more advanced gynecomastia symptoms.
  • 2.5mg will kill gyno in its tracks if 1.25mg isn’t enough for you, but at that point, you’re looking at maximum estrogen suppression, and you’ll undoubtedly feel absolutely terrible.

Letrozole needs to be tapered down in dosage as you come off it so you don’t suffer an estrogen rebound.

Letrozole Dosage for PCT

Of all the AIs, I would put Letrozole as the most unsuitable for PCT use. Simply using Letrozole for on-cycle anti-estrogen purposes can be taxing enough, and this is typically shorter-lived than a PCT cycle that needs to run for several weeks.

Although Letrozole has been shown to increase LH and FSH potentially, this AI is unlikely to be effective at giving you any beneficial testosterone-stimulating effects during PCT, and a SERM (or even Aromasin) is an infinitely better option. If you are insistent on using Letrozole for PCT, consider it for the first one to two weeks only at a low dose of under 1mg every three days and accompany its use with a SERM for another 2-4 weeks.

Dosing Schedule, Half-life, and PCT Length

Letrozole’s half-life is anywhere from 2 to 4 days[2]. I prefer to take it once every three days. Most guys would only want to take Letrozole on a daily basis when there’s a lot of gear being taken; otherwise, every 2-3 days is adequate.

As it would be highly unusual (and not recommended) to use Letrozole for PCT, I can only say that if you DO decide to include this AI in your PCT cycle, then limit its use to two weeks at the most, followed by Nolvadex.

Proper Administration and Timing

If you’ve bought Letrozole in tablet form (pharmaceutical grade or from an underground lab), it’s a simple once-daily administration. The official medical guidelines state that it can be taken with or without food – but it should be taken at the same time each day so you’re able to maintain consistent levels of the drug in your system.

Buying pharma-grade Letro makes it easy to pop a simple tablet as needed every two or three days. Liquid research chemical Letro is best taken under the tongue for proper absorption or as directed by your supplier.

Letrozole vs. Other PCT Options

Letrozole isn’t an AI you’ll want to use for PCT. As you know, this AI is more than capable of destroying your estrogen levels (almost completely to 100%), and that’s not what we need during PCT – you want your estrogen to be at a healthy level and in balance with the natural testosterone you need to recover after using steroids.

When it comes to gyno control and reversal, we have plenty of other options to consider alongside Letrozole. How do they stack up, and when would you choose Letrozole over other AIs or SERMs?

Letrozole vs. Clomid

Clomid is a SERM, which is a very different type of drug from Letro (an AI). A common misunderstanding is that Clomid will reduce your estrogen levels. SERMs do not reduce total estrogen! Instead, Clomid will bind to specific estrogen receptors while leaving your circulating estrogen untouched.

Clomid SERM
Clomid SERM

When it comes to our usage of Clomid and Letrozole, they really are like chalk and cheese: Clomid is one of the best PCT compounds we can use to restore testosterone function. Letrozole, on the other hand? I would strongly advise against using it for PCT. However, Letrozole can be exceptional at zapping gynecomastia quickly.

Clomid is not a great on-cycle ancillary and won’t be your first choice for controlling estrogenic side effects. Still, unlike Clomid, Letrozole can and will crush your estrogen to dangerously low levels. In short? These are two very different ancillaries for different purposes: Clomid for PCT and Letro for gyno control.

Letrozole vs. Arimidex

Of all the AIs, Arimidex is closest to Letrozole in terms of its mechanisms of action as they’re both nonsteroidal AIs. This means they both bind reversibly to the aromatase enzyme. Despite this, Letrozole is still a more potent AI than Arimidex, and almost everyone will find it a less tolerable AI to use compared to the more popular Arimidex.

Arimidex Aromatase Inhibitor
Arimidex Aromatase Inhibitor

I would very rarely choose to use Letro over Arimidex! Arimidex is excellent at reducing water retention. Although technically, Letro should also reduce fluid retention, we don’t use it for this purpose because it would require use over most of your cycle. And as we know, Letrozole is far too harsh to be running for weeks on end.

It’s well known that Letrozole reduces estrogen more strongly than Arimidex[3], making Letro the more difficult AI to use. The risk of crushing your estrogen is that much higher compared to using Arimidex.

Letrozole vs. Aromasin

Aromasin is the only AI that is reasonable to consider for PCT because it can effectively stimulate LH and FSH (although you’ll still need to use Nolvadex with it). On the other hand, would you want to use Letrozole for PCT? I would say no: Letro isn’t really suitable for PCT use.

Aromasin Aromatase Inhibitor
Aromasin Aromatase Inhibitor

So what about gyno – is Aromasin or Letrozole better? Aromasin is an all-round anti-estrogen that helps with gyno and water retention, and it’s a much more tolerable drug to take than Letro. I would only ever use Letrozole over Aromasin if I badly need it to get rid of worsening gyno because I know it’s going to destroy my estrogen levels if I’m not extremely careful with the dosage.

Letrozole Side Effects in Men

There are a few significant differences in the way that female medical patients take Letrozole and how we will use it for our on-cycle needs. Most importantly, when it comes to side effects, women will often be prescribed Letrozole for several years. In comparison, we will typically use Letrozole only for a matter of days!

Unfortunately, that doesn’t mean we get away with zero side effects with this AI because it is VERY powerful, and that’s a good reason to limit its use to only when you really need it. Virtually all the side effect risks relate to estrogen deficiency as a result of Letro’s potent anti-estrogenic effects. Here are the side effects that you could potentially experience when taking Letrozole:

Loss of libido and sexual function

Possibly the most complained about adverse effect of Letro is the way it can kill your libido and do so quickly and fully. It’s also played havoc with sexual function in a lot of men, resulting in complete erectile dysfunction in the worst cases. This is a direct result of you nuking your estrogen levels and possibly taking too high of a dose of Letrozole.

If ED and loss of libido are distressing you and you still want to keep using Letro, then you’ll want to get at least bloodwork done to check your estrogen levels to rule out any other causes.


Extreme fatigue can develop if you’ve crushed your estrogen on Letro. At the more extreme end are guys who feel the need to nap all day long. This is a clear sign that you either need to taper off Letro and stop using it or drop the dosage in half. Your estrogen will need to be within normal range to prevent debilitating fatigue.

Joint Pain

Estrogen plays a vital role in bone and joint health, so once again, once your levels drop drastically (and Letro can drop estrogen levels by 90% or more), your bone strength reduces due to decreased bone mineral density. On the upside, some of the AAS we use will actually increase bone mineral density, and this can help offset this adverse Letrozole effect.

It’s well known that osteoporosis is a risk factor for long-term use of Letrozole. We shouldn’t have to worry about any permanent damage to the bones or joints when using Letro short term, and your pain should disappear once you’ve stopped taking Letrozole and your estrogen levels have bounced back to within the normal range.


Letrozole can increase both cholesterol and blood pressure. Studies on female patients found a significant increase in total cholesterol levels and LDL when measured after two months and again at four months[4].

Again: while an increase in cholesterol is always unwanted for those of us using steroids that already cause their own negative impact on cholesterol (and blood pressure), short-term use is unlikely to result in permanent health concerns.

With numerous clinical trials involving female breast cancer patients, other side effects that were reported include mostly temporary issues like:

  • Hot flashes
  • Excess sweating
  • Nausea
  • Headaches

Where to Buy Letrozole?

We’ll often turn to Letrozole as a desperate last attempt to get rid of gynecomastia symptoms. But what if you can’t find any? What if it takes weeks to arrive? If you don’t already have a reliable source for Letrozole, then this is what I do: My answer is to go straight for the research chemical suppliers if you need Letro ASAP.

Availability of Letrozole

Letrozole is a very commonly prescribed prescription drug in the US and many other countries, but that doesn’t mean it will be easy to buy without a prescription.

  • Black market sellers are one option, but many are less inclined to advertise their prescription medications for sale thanks to the legal issues other suppliers have faced.
  • Underground labs won’t stock Letrozole as commonly as the more popular AIs, but you will find some suppliers with Letro in tablet form.

So where does that leave us?

Research chemical suppliers provide us with a reliable option, even if a little inconvenience is that you’ll usually buy Letrozole in liquid form from these sources rather than tablets. For most of us, the research chemical path is the quickest and most reliable way to get Letrozole, and if you have a reputable supplier, then quality should not be an issue.

In most major countries, Letrozole is only legal to purchase and use if you have a legitimate doctor’s prescription. And with Letrozole only being prescribed for breast cancer treatment (and occasionally off-label for gynecomastia and infertility), the chances of you obtaining a prescription are probably very low.

Buying black market (which typically means unauthorized imports) Letrozole is technically illegal. However, it will be the importer and supplier of black market Letrozole who will have the attention of authorities. Wherever you’ve managed to get your Letrozole from, you’re unlucky to face any legal complications if you’re possessing a small amount without a prescription.

There is an exception here: Research chemical Letrozole (typically sold in liquid vials) is currently legal to sell and buy – technically for research purposes only. Still, for those looking for the most legal way of getting Letrozole without a prescription, research chemicals are the way to go.

Typical Pricing

Femara tablets are available throughout most of the world, and if you can find this brand, you’re getting the best possible quality of Letrozole, but it will also be the most expensive. Generic pharmaceutical Letrozole is also available, and as long as they’re legitimate generics, the quality should be just as good as genuine Femara and at a lower cost.

Compared to some other AIs that we use, Letro is actually one of the more affordable products.

  • Some online pharmacies (prescription required) sell 30 tablets of 2.5mg at a little over $100.
  • Peptide and SARMs suppliers (which are usually research chemical suppliers) provide 30ml vials of 2.5mg/ml for under $40.

Keep this in mind: We use very low quantities of Letrozole, and even a single 30-tablet box is likely to last you over several cycles.

Final Thoughts

Letrozole is a last resort option for me for estrogen/gyno control. This is not an AI you want to jump on to “just in case.” And anyone who uses it (or even is just thinking about using it) should already know this: You SHOULD expect to feel like crap on Letro. It’s the trade-off for getting rid of gyno, but it’s up to you if you think it’s worth it.

Guys so distressed by gynecomastia and not seeing results from other AIs will turn to Letrozole in desperation. There’s nothing wrong with doing that – as long as you know what you’re getting yourself into with this amazingly powerful AI.


— Furious Joe

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Joe Robles a.k.a Furious Joe

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What I talk about here is something I've done. From anabolic steroids to SARMs to peptides and ancillary drugs, I've done it at some point in my life, and I can relate.

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