Think Twice: The Downsides of Using Anastrozole to Boost Testosterone

Men's sexual health is influenced by sex hormones. Contrary to popular belief, this includes both testosterone (T) and estrogen, even though the latter is known as the “female sex hormone.” As you age, testosterone levels naturally decline. This can lead to reduced sex drive, fatigue, erectile dysfunction (ED), and loss of lean muscle mass. 

Neither clomiphene (Clomid) nor anastrozole carries FDA approval for treating low testosterone in men. A physician weighs TRT eligibility, fertility goals, and side-effect risk before recommending either one. If clinically indicated, the go-to treatment for male hypogonadism (low T) is testosterone replacement therapy (TRT). However, TRT may be contraindicated in certain cases. This is why some healthcare professionals turn to alternative (off-label) treatments such as clomiphene (Clomid) and less frequently, anastrozole (Arimidex).

• Anastrozole inhibits the enzyme aromatase, thereby reducing estrogen levels. It is primarily used to treat breast cancer in women. Using anastrozole for men with low T is an off-label application that has not received regulatory approval in the U.S.(and might sound good in theory but is not an effective option) 
• The evidence regarding the efficacy of anastrozole for men with low T is mixed, and it is unclear whether this treatment provides significant benefits. 
• There may be other ways to increase testosterone production. Consider comprehensive solutions that address the underlying causes of low T. 

Anastrozole: What is it? 

Anastrozole is a prescription medication that belongs to a class of drugs called “nonsteroidal aromatase inhibitors.” It works by blocking the enzyme aromatase,  which is responsible for converting testosterone into estrogen, particularly its most potent form—estradiol. Although the net result is lower estrogen levels, this does not necessarily translate into higher testosterone. The relationship between testosterone and estrogen is a little more complicated than that.  

So, what is anastrozole used for? Healthcare professionals typically prescribe anastrozole and other aromatase inhibitors to women with breast cancer. The drug is approved by the Food and Drug Administration (FDA) for the treatment of hormone-receptive breast cancer in postmenopausal women.¹

Can Men Use Anastrozole? 

You may have heard that anastrozole is sometimes prescribed to men with low testosterone, particularly in cases where estrogen levels are high. However, this is an off-label use, which means it has not been approved by regulatory agencies. 

You may be wondering, why consider an alternative to TRT? Despite its efficacy, this first-line treatment can sometimes be contraindicated or have adverse effects that limit its use. One such effect is the suppression of sperm production (spermatogenesis), which can harm reproductive function. This side effect may limit the use of testosterone in younger men who wish to maintain fertility. To circumvent these issues, healthcare professionals may prescribe off-label medications that work differently from TRT. 

Studies report conflicting results about the efficacy of anastrozole for male hypogonadism (low T) and low fertility. Some studies have found that the drug significantly reduces estradiol levels, leading to increased follicle-stimulating hormone (FSH) production and in some cases, increased T concentration.^2,3 

Yet, some researchers point out that despite the effect on sex hormone concentrations, actual clinical improvements are often lacking. Indicators such as metabolic and psychological health, insulin sensitivity, body composition, and exercise capacity do not always show significant improvement.^4,5

What's the Difference Between Anastrozole and Clomid for Men?

Anastrozole and clomiphene (Clomid) work through different mechanisms. Anastrozole blocks the enzyme that converts testosterone into estrogen, while Clomid blocks estrogen receptors in the brain, which signals the pituitary gland to release more luteinizing hormone and, in turn, more testosterone.² Neither drug carries FDA approval for treating low testosterone in men, and a physician weighs fertility goals and side-effect risk before recommending either one.

Anastrozole and Male Fertility

Unlike testosterone replacement therapy, which halts endogenous sperm production by suppressing pituitary gonadotropins, anastrozole promotes follicle-stimulating hormone release by lowering circulating estradiol. The medication has been specifically evaluated as an intervention for male infertility, as outlined in the previously cited Human Reproduction Update review. Studies report conflicting results on actual fertility outcomes, meaning aromatase inhibition does not reliably restore fertility for every individual. For men prioritizing reproductive potential, this preservation of gonadotropin signaling provides a clear rationale to discuss anastrozole with a physician alongside a comprehensive diagnostic fertility workup.

How Does Anastrozole Work In Men? 

Anastrozole, like other aromatase inhibitors, blocks the enzyme aromatase. This enzyme is present in both men and women and is necessary for the conversion of testosterone into estrogen. 

Lowering estrogen levels in men can sometimes result in higher testosterone. This is because estrogen and testosterone are part of a hormonal balance, and reducing estrogen can decrease the feedback inhibition on the hypothalamus and pituitary gland. This can lead to an increase in hormones such as follicle stimulating hormone (FSH), luteinizing hormone (LH), and subsequently testosterone. 

However, the relationship between estrogen and testosterone is complex. While some estrogen blockers can increase testosterone levels by limiting the amount of estrogen present or active in the body, this doesn't always translate into significant clinical benefits. It's important to approach this under medical supervision, as both hormones play crucial roles in overall health and well-being

Anastrozole's potential therapeutic benefits are narrow and studied for specific situations, listed below. However, these benefits come with potential costs, particularly when used to boost testosterone. 

Anastrozole for Men: Potential Benefits

• May raise FSH and LH, and in some men testosterone, by reducing the feedback inhibition estrogen places on the hypothalamus and pituitary gland.^2,3
• Used off-label to delay puberty in boys with precocious puberty.¹
• Studied as an option for men whose testosterone has declined with aging or obesity.¹

These are the drug's studied mechanisms. They are not guaranteed outcomes, and higher hormone levels on a blood test do not always translate into a felt clinical benefit. The trade-off is a set of side effects a physician weighs before considering it. In the next section, we'll explore the side effects of anastrozole. 

Fat loss is not among anastrozole's studied benefits, contrary to common bodybuilding forum claims that aromatase inhibitors burn body fat. The medication's documented actions focus on increasing luteinizing hormone, follicle-stimulating hormone, and serum testosterone, while clinical data shows no reliable improvement in body composition and lists altered fat metabolism as a reported risk. For men seeking body composition changes, a physician-guided hormonal evaluation and the targeted strategies outlined in the Other Ways to Increase T section below provide the constructive path forward.

How Quickly Does Anastrozole Work for TRT?

Anastrozole has no established onset window for men, because most trials measuring its effect on testosterone and estradiol run only a few weeks to months and report inconsistent results.^4,5 A hormone shift shows up on a follow-up blood test rather than in how a man feels, since symptom changes and lab values don't always move together.⁴

Side Effects of Anastrozole 

Most of the safety data behind anastrozole's side effects in men comes from women treated for breast cancer rather than from men. The most common side effects include: 

• Hot flashes
• Joint pain
• Bone thinning (osteoporosis) and subsequent fractures
• Erectile dysfunction (ED)
• Sleep disturbances
• Problems with fat metabolism. Estrogen regulates fat distribution in men, so suppressing estradiol provides a plausible mechanism for fat redistribution toward the abdomen. Direct clinical data on male abdominal fat changes is limited because most safety data is extrapolated from women treated for breast cancer, and the medication produces no reliable fat-loss or body-composition benefit. A physician monitors estradiol levels alongside metabolic markers on regular blood panels to prevent over-suppression and manage changes in body composition.
• Problems with the heart and blood vessels. 

In rare cases, patients may develop the following side effects:

• Ulcers and blisters on the skin
• Allergic reactions
• Liver damage
• Bone loss 

Anastrozole can be stopped, but that decision should be made with the prescribing physician, since discontinuing it can shift hormone balance again. Joint problems are the most common reason men and their physicians decide to stop treatment.¹ These issues arise from reduced bone mineral density caused by prolonged low estrogen levels, and they typically begin as pain and swelling.

Having your estrogen levels drop too low can also affect sexual function and cause ED. Although evidence linking anastrozole to ED is limited, maintaining healthy levels of sex hormones is crucial during hormone treatment. 

Who Shouldn't Take Anastrozole?

Men with a history of osteoporosis, low bone density, or bone fractures are generally not good candidates for anastrozole, since prolonged low estrogen further reduces bone mineral density and raises fracture risk.¹ The same caution applies to men with cardiovascular disease or liver problems. Anastrozole's most serious reported side effects include cardiovascular events and liver damage, and it carries no FDA approval for any use in men.¹ A physician reviews bone health, heart history, liver function, and current medications before considering it for low testosterone.

Given the bone-thinning and cardiovascular risks described above, a physician overseeing anastrozole treatment typically monitors with periodic bone density scanning and follow-up hormone bloodwork. That bloodwork tracks estradiol and total testosterone together, so treatment can be adjusted before estrogen suppression goes too far in either direction. This proactive monitoring allows a physician to catch and manage these risks early, so you do not have to watch for warning signs alone.

What to Avoid While Taking Anastrozole?

Anastrozole should not be combined with tamoxifen or other estrogen-containing products, including hormone replacement therapy, estrogen creams, or hormonal birth control, since these can lower how well it works.¹ Certain herbal supplements marketed for menopause symptoms carry the same caution, according to a review of anastrozole drug interactions. Tell your prescriber about every medication and supplement you take before starting anastrozole, and again before adding anything new.

Is Anastrozole Safer Than TRT?

Anastrozole and TRT are not interchangeable. They treat different problems and carry different risk profiles, so there is no simple answer to which one is safer. TRT is FDA-approved for diagnosed hypogonadism, and its main fertility-related side effect, suppressed sperm production, is reversible for most men after stopping. Anastrozole carries no FDA approval for men, and its studied risks, including bone loss and cardiovascular effects, mostly come from long-term use in women.¹ A physician who has reviewed your labs, fertility goals, and overall health can say which option, if either, fits your case.

Co-Prescribing Anastrozole Alongside Testosterone Replacement Therapy

Beyond its role as an alternative to testosterone replacement therapy, anastrozole is commonly co-prescribed alongside active TRT to manage estradiol that rises when the body converts supplemental testosterone through the aromatase enzyme. Because individual conversion rates vary, a prescribing physician evaluates blood panels alongside clinical symptoms to determine whether introducing an aromatase inhibitor is appropriate. A physician manages this adjustment directly as part of ongoing TRT care to keep biomarkers within an optimal range. Routine lab reviews provide continuous clinical oversight so you never have to navigate estrogen management on your own.

Other Ways to Increase T

It's easy to miss the bigger picture when relying solely on medication to address low testosterone levels. Changing your everyday habits can make a significant difference and lead to more lasting results. 

• Exercise regularly. Men weren't meant to sit at a desk or on the couch all day. Boost your T levels with consistent training, including both high-intensity and strength exercises. However, avoid overtraining, as too much exercise can also reduce T levels. 
• Eat a nutritious diet. Your food should contain adequate amounts of protein, carbohydrates, and fats, and be rich in vitamins and minerals. A diverse and clean approach to nutrition is the best strategy.
• Maintain a healthy weight. Excess body fat is metabolically active and may disrupt your T production. Shedding the extra pounds can naturally enhance your hormonal health. 
• Get quality sleep. Focus on getting enough deep, restorative sleep to balance your hormones. 
• Manage stress. Learn to relax and reduce your stress levels, as stress hormones can negatively impact testosterone production. 
• Stay away from alcohol and drugs. Heavy drinking, recreational drug use, and anabolic steroids can all negatively impact your T levels. 
• Finally, try TRT. TRT is highly effective and safe when used correctly and under medical supervision, and TRT cost varies by provider and plan. 

Opt Health physicians have helped countless men balance their sex hormones. We go beyond anastrozole or any other single drug. Our strategy involves taking an in-depth look at your health condition, understanding the underlying causes, and developing a comprehensive treatment plan. We believe the best approach combines lifestyle interventions with effective treatments.

How Much Does Anastrozole for Men Cost?

The cost of anastrozole for men is not standardized because prescribing the medication for low testosterone is an off-label use instead of an FDA-approved indication. Off-label prescribing like this faces inconsistent insurance coverage and is often not covered at all. Consulting with a physician gives you an accurate, current price for your situation, since your actual cost depends on your pharmacy, assigned dose, and insurance benefits. That initial consultation also confirms whether anastrozole is the right clinical fit for your hormone levels before out-of-pocket expense becomes the deciding factor.

The Bottom Line 

While anastrozole may seem like a quick fix for symptoms associated with low T levels, consider whether you want fast or lasting solutions. Remember that treating hypogonadism (low T) with aromatase inhibitors is not FDA-approved and comes with serious side effects, such as bone loss. 

There may be better ways to manage your low T, such as undergoing a detailed health evaluation with a trusted healthcare provider. At Opt Health, we’ll ask ourselves, what is the underlying cause of this patient’s low T? Regular exercise, quality sleep, and a healthy diet might do wonders to improve your hormonal balance. With a personalized care plan that addresses your overall health, you can regain your energy, vigor, and stamina for years to come. 

The reference interval itself, and what it does and does not tell you, is set out in estradiol levels in men.

For a mechanism that raises testosterone without blocking aromatization, see how enclomiphene raises testosterone.