How to Stop Testosterone Aromatization in Men

Testosterone converts into estrogen

As a man, your body normally produces about 45 micrograms of estrogen (E) per day via a process called aromatization.

That’s a natural process that occurs mainly in your fat tissue but also in your bones, brain, arteries, liver, and testes.

An enzyme called aromatase resides there and it converts some of your testosterone into estrogen in order to maintain a balance between the two hormones.

This balance is key for the normal function of a man’s body, since E plays an important role in male sexual development, mood, bone mineral density, and hormonal regulation.

Therefore, both too low and too high E levels can lead to health problems and require proper treatment.

Why and when testosterone converts into estrogen?

There are several types of estrogen but E1 (estrone) and E2 (estradiol) are the main ones seen in men. The process of aromatization involves the conversion of testosterone to E2.

Estradiol is the most potent form of estrogen in the male body

The process of aromatization occurs all the time in healthy individuals since estrogen is needed for several physiological functions. For example, E2 plays a major role in increasing bone mineral density during puberty and then maintaining it throughout life.

Estradiol also acts as negative feedback for the production of gonadotropic hormones from the pituitary gland. Those are the follicle-stimulating hormone (FSH) and luteinizing hormone (LH) which regulate testosterone synthesis in the testes.

If T levels rise, more of it will be converted to E2. This increases estrogen’s suppressive effect on FSH and LH which reduces testosterone back to normal ranges.

The level of inhibition depends on whole-body E2 levels, including the amount aromatized in your fat tissues. If you have too much body fat this means you likely have higher activity of the aromatase enzyme as well.

Therefore, a higher percentage of your testosterone will be converted into estrogen. The latter will suppress FSH and LH leading to low T but normal or elevated E2 levels.

Heavy chronic alcohol consumption may also increase the activity of the enzyme and increase estrogen levels

What problems can aromatization lead to?

Normal estrogen levels in men should be in the range of 10⁠-⁠40 pg/ml. E2 above the upper range may lead to symptoms, especially if it is in combination with low T levels.

Studies reveal that high estradiol levels may cause sexual problems such as erectile dysfunction. On the other hand, too low of estrogen may result in delayed ejaculation or an inability to reach a climax at all.

In male adolescents, high estradiol may lead to premature closure of the epiphyseal plates and short stature in men.

According to researchers, maintaining estradiol within an optimal range is also important for normal spermatogenesis. If estrogen is too high it may lead to infertility.

Furthermore, estrogen that’s significantly elevated may lead to swelling or enlargement of breast tissue.

Enlargement of breast tissue

The condition is also known as gynecomastia and its initial signs develop after 3-6 months of exposure to elevated estrogen levels. Studies report that it takes 6-9 months for gynecomastia to fully develop.

At first, it develops as increased sensitivity and tenderness around the mamilla which is reversible. If left unchecked it turns into swelling and gynecomastia which is no longer completely reversible and has to be treated surgically.

Scientists report that the degree of aromatization and thus estrogen levels tend to increase with age. This may contribute to sexual problems and reduced fertility which are more common in middle-aged and older men.

Can TRT cause high estrogen?

Testosterone replacement therapy (TRT) is an FDA-approved treatment for men with low T. It requires regular application of exogenous testosterone, which has the same benefits and potential to get aromatized in your body as naturally produced T.

Legal TRT prescribed by a medical doctor may also increase your estrogen, but it is not likely to cause high E2 levels.

It aims to maintain serum T levels in the mid-normal range, which ensures that your estrogen levels will also remain within references. The rate of conversion is dose-dependent, and higher doses of TRT will also lead to higher estradiol levels.

Proper T dosing is key for preventing high estrogen levels during treatment

Always follow your doctor’s recommendations and avoid increasing your dose without medical consultation.

Over-the-counter testosterone products such as herbal extracts and supplements have unreliable hormonal effects. The majority of their ingredients may be ineffective since they lack scientific support while 10% may even reduce T levels. The effects on estrogen levels remain largely unstudied.

How SERMs and AIs stop testosterone from aromatization

If your estrogen levels are too high and you have symptoms, then your doctor may consider medications that block estradiol receptors or prevent aromatization in the first place.

How to prevent testosterone aromatization

The two main options are aromatase inhibitors (AIs) and selective estrogen receptor modulators (SERMs).

AIs work by blocking the aromatase enzyme and preventing the conversion of T into E2. Therefore, aromatase inhibitors reduce all of the effects of estrogen in the male body, including the benefits for bone mass.

On the other hand, SERMs do not prevent this conversion but modulate the receptors for estrogen instead and block its effects in areas such as breast tissue.

However, SERMs have tissue-specific action and also increase estrogen activity in other tissues such as bones. Therefore they increase bone mineral density and prevent osteoporosis.

Both SERMs and AIs can be safely taken with TRT in case of elevated estrogen levels during treatment

Besides, the medications can help you remain fertile during TRT if you have secondary hypogonadism. SERMs and AIs prevent the suppressive effect of E2 on gonadotropic hormones.

This allows for natural testosterone synthesis and spermatogenesis to continue.

Furthermore, AIs and SERMs may even elevate the levels of LH and FSH. This can help boost and sometimes even normalize testosterone in men with secondary hypogonadism.

However, the effect is unreliable and the medications are not FDA-approved for treating low T in hypogonadism. Nevertheless, off-label use of AIs and SERMs, mainly for the treatment of low T related to obesity.

Keep in mind that AIs and SERMs are available only after a medical prescription. Purchasing them without one is illegal.


Raloxifene is a prescription medication, which modulates the estrogen receptors in the body. It’s more popular as the brand name Evista.

Evista (raloxifene)

Raloxifene is a SERM that can help reduce the negative effects of elevated estrogen by blocking some of its receptors. Furthermore, medication can increase testosterone and improve fertility in men with idiopathic oligozoospermia.

Similar to other SERMs, it blocks the E2 activity on breast tissue and effectively reduces the risk of gynecomastia.

Also, it is highly effective in treating pubertal gynecomastia – even more so than other SERMs. Raloxifene at a dosage of 60 mg/day taken for 3 to 9 months was sufficient for significantly reducing breast size.

On the other hand, it stimulates the estrogen receptors in bone tissue, which leads to increased bone mineral density and reduced risk of osteoporosis.

The majority of trials do not report any side effects in men. Raloxifene is contraindicated in men and women with a history of thrombosis.


Anastrozole is a prescription medication sold under the brand name Arimidex. It is an aromatase inhibitor (AI) and as such, it can effectively suppress the conversion of T to E2.

Arimidex (anastrozole)

Studies report that 1mg Anastrozole daily led to a 35% reduction in E2 levels as soon as the 4th week after starting the therapy with a maximum effect at the 8th week. The medication also led to a 100% increase in testosterone levels, in older adults with low T.

However, long-term use of Anastrozole may increase the risk of low bone mineral density and osteoporosis, since it prevents the beneficial effects of estradiol on these issues.

Furthermore, unlike SERMs, anastrozole and other AIs are not effective in treating gynecomastia.

Side effects related to the therapy may include bone and joint pain, bone fractures, hypertension, and allergic reaction.


Letrozole is another AI sold under the brand name Femara. The medication is available only with a medical prescription and its standard dosage is 2.5 mg per day.

Femara (letrozole)

Trials reveal that Letrozole can lead to up to a 62% reduction of estradiol levels in older men after 4 weeks of therapy. T levels also increased by 99%.

In comparison, the medication led to a 42% reduction in estrogen and a 146% increase in testosterone in younger men.

Side effects are similar to that of other AIs.


Tamoxifen is a prescription drug, sold under the brand name Nolvadex. It is a SERM, and as such it does not block the aromatization of testosterone to estradiol. The standard dose is 20 mg per day.

Nolvadex (tamoxifen)

Nevertheless, it is effective in preventing and treating the effects of high estrogen in the male body, especially in the management of breast tenderness and swelling.

Tamoxifen is significantly more effective than anastrozole or other AIs in preventing and treating gynecomastia. Besides, it does not increase the risk of bone loss and osteoporosis.

On the other hand, tamoxifen leads to a lower increase in T levels compared to AIs – about 60% according to studies.

The rare but serious adverse reactions that may occur in men using tamoxifen include an increased risk of thrombi formation and liver toxicity.


Clomid is the brand name of the SERM called clomiphene. It is a prescription medication that’s usually taken daily at a dose of 25 mg.

Clomid citrate

Clomiphene citrate can raise T levels similarly to other SERMs. Compared to AIs such as Anastrozole, the increase is less significant, but it doesn’t increase the risk of low bone density and bone fractures.

Clomid is generally well tolerated. Rare but serious side effects may include an increased risk for thrombosis and liver damage.

Contraindications for clomiphene use include an allergy to the medication, history of thrombi, liver diseases, thyroid dysfunction, and pituitary problems.

What are the best natural aromatase inhibitors (estrogen blockers)?

There are several natural ways to decrease the activity of the aromatase enzyme and prevent T conversion into estrogen in men.

Natural ways to decrease the activity of the aromatase

For example, some foods such as white button mushrooms contain natural inhibitors for this enzyme.

The studies proving these effects are performed on breast cancer cells as inhibiting the enzyme also inhibits the proliferation of that malignant tumor. Mushrooms contain either multiple inhibitors or more than one inhibitory mechanism which makes them very effective in blocking aromatase.

Another powerful inhibitor of T aromatization is a compound called Indole-3-carbinol (I3C). It is found in relatively large quantities in all cruciferous vegetables, such as broccoli, cabbage, cauliflower, brussels sprouts, collard greens, and kale.

Furthermore, I3C converts estrogen into less potent hormones and increases its excretion through urine which further lowers estradiol levels.

The polyphenols (antioxidants) in pomegranates called ellagitannins are also a candidate for natural aromatase inhibitors. Experiments reveal that the compounds can effectively block the conversion of T in vitro.

Yet, one of the most effective methods to reduce the aromatase activity in your body is to reduce your body fat percentage

This means that if you are overweight or obese, your best option to lower estrogen and boost testosterone is to lose weight. The most effective way to do that is by improving your diet and increasing your physical activity.

Get a free consultation with our medical expert for any questions about hormone replacement therapy

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