Over time, levels of the hormones testosterone and estrogen can become imbalanced in men, potentially causing health problems. Medications called estrogen blockers are among the treatment options for those with low testosterone and higher estrogen.
This article discusses how estrogen functions in men and symptoms of a testosterone and estrogen imbalance. It also covers treatments that block estrogen and when to see a healthcare provider.
The terms “male” and "men" are used in this article to refer to people who identify as male and have typical reproductive organs of a cisgender male. We recognize that some people who identify as male do not have the same anatomy as depicted in this article.
Estrogen in Men
Estrogen is often thought of as a female hormone, as the ovaries produce much of the hormone. However, men also have estrogen in their bodies. About 20% of a man's estrogen is produced by the testes. The rest is produced in body fat, the brain, skin, and bones.
Estrogen in the male body impacts many functions, such as:
- Maintenance and growth of bones
- Coordination of head and eye movement to support vision
- The type and location of fat in the body and metabolism
- Sexual functioning in relation to libido (sexual drive), erectile functioning, and the creation of sperm
Age-Related Testosterone Decrease
Testosterone typically decreases in the body as men get older, referred to as late-onset hypogonadism. Though the exact prevalence is not certain, researchers believe up to 25% of men may experience a decrease in testosterone as they age.
Symptoms of Estrogen and Testosterone Imbalance
Changes to the ratio of estrogen and testosterone in the body can result in health problems for some people. For example, in people with late-onset hypogonadism, lower testosterone levels and an increase of androgens being converted to estradiol is associated with a number of health issues, including:
- Reduced sex drive
- Reduced muscle mass and energy
- Erectile dysfunction
- Hot flashes
- Decreased testicle size
- Gynecomastia (enlarged breast growth)
- Low-energy fractures (where bone fractures occur due to falling from a standing height or less)
Aromatase excess syndrome is a rare genetic condition that results in higher levels of estrogen. It can affect some young men and lead to late childhood developmental symptoms. In addition to breast growth, the associated symptoms include:
- Quicker than normal physical development that stops sooner than others
- Short stature
What Are Normal Testosterone Levels?
Estrogen blockers are a type of treatment that reduces the amount or functioning of estrogen in the body.
Several estrogen blocker medications used to treat the imbalance of testosterone to estrogen were initially developed for use in treating breast cancer in women. However, they have been prescribed for off-label use in male patients.
Off-Label Use of Medications
Prescribing drugs "off-label" means that a healthcare provider has prescribed a medication that is approved by the Food and Drug Administration (FDA) but that is not approved for the condition or purpose it is being prescribed. A provider may prescribe an approved drug to treat a condition or purpose that the drug was not approved for at their own professional discretion.
Medications used as estrogen blockers include:
- Aromatase inhibitors (AI): This medication can increase testosterone, along with other hormones, by inhibiting the ability of androgens to be converted to estradiol in the body. This decreases the overall level of estrogen in the body. The medication also acts on the hypothalamus and pituitary gland to increase luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in the body, which may support healthy sperm. Some available AI medications used for this purpose are anastrazole and letrozole.
- Selective estrogen receptor modulators (SERM): These medications bind to estrogen receptors to prevent estrogens from binding with each other. A similar function of releasing LH and FSH can also be achieved by use of SERM. Common SERM medications used to address the hormonal balance in men include tamoxifin and clomiphene citrate.
Estrogen-blocking medications have been prescribed for off-label use in those with low testosterone for some time and are often well-tolerated. However, there aren't established guidelines for their use in men. More long-term studies are needed to establish efficacy and safety of the medications for this specific purpose.
That said, some research has found these reported side effects:
- AI: In general, AI are well-tolerated by those who use them for this purpose. Side effects may include nausea, increase in liver enzymes, headaches, and hot flashes.
- SERM: Researchers have noted that clomiphene citrate has minimal side effects while being able to increase testosterone levels and improve bone mineral density and androgen deficiency. Rare side effects for clomiphene citrate include headaches, changes in vision, and gynecomastia (enlargement of male breasts). Use of tamoxifen may involve more significant side effects, including gastrointestinal upset, risk of blood clots, and cardiovascular problems.
Natural Estrogen Blockers
While there is no solid evidence supporting the following as effective estrogen blockers, some proponents believe they can be used for this purpose:
- Maca root: Maca is a cruciferous plant that is found in Peru. It has been touted as an estrogen blocker and fertility enhancer in men, but there is no scientific evidence to support these claims.
- Wild nettle root: Wild nettles are leafy shrubs that are purported to contain compounds that act as natural estrogen blockers.
- Chrysin: Chrysin is a flavonoid that can be found in passionflower, honey, and bee propolis. Some research suggests that chrysin may block estrogen, however this has not been confirmed in human studies.
- Grape seed extract: There is some evidence that grape seed extract has been shown to act as an aromatase inhibitor, or estrogen blocker, in post-menopausal women.
Are There Alternatives to Estrogen Blockers?
While research findings are mixed, there is some evidence that testosterone therapy may decrease estrogen levels in men. One 2018 study found that estrogen levels decreased in transgender men who received testosterone therapy.
Strategies to avoid estrogens in the environment (which is a healthy thing to do in general) include:
- Avoiding meat products made from animals raised with synthetic hormones
- Avoiding plastic food containers, plastic water bottles, and plastic wraps. These can leach bisphenol A (BPA), an endocrine disruptor, into food and beverages, especially when heated.
- Avoiding shampoos and other personal care products containing parabens
- Eating lower-fat foods. High-fat diets, especially high-fat dairy products, are linked to excess estrogen production.
- Eating more cruciferous vegetables, such as kale, broccoli, and Brussels sprouts. These vegetables are thought to regulate estrogen.
When to Talk to Your Healthcare Provider
If you are experiencing symptoms associated with an imbalance of testosterone and estrogen, particularly reduced sexual desire and erectile dysfunction, speak with a healthcare provider to help you determine the exact cause. To investigate whether hormones may be at the root of your symptoms, they may do a blood test to measure your hormone levels.
If your hormone levels meet the criteria for a diagnosis such as hypogonadism, they can also advise on treatment options. These can range from changing lifestyle factors (such as sleep and diet) to medications.
When estrogen levels in men are higher than testosterone levels, estrogen blockers may be needed to restore the balance of these hormones and prevent health problems caused by a rise in estrogen. Most estrogen blockers are well-tolerated, but there are some side effects. If you notice symptoms such as erectile dysfunction, gynecomastia (enlarged breasts), or hot flashes, contact your healthcare provider.
Frequently Asked Questions
Is it safe to take estrogen blockers and testosterone at the same time?
Some research supports the safe and effective use of estrogen blockers and testosterone therapy at the same time. Both may be used because testosterone therapy can increase the amount of estrogen in the body due to an increase in aromatase activity.
Aromatase is an enzyme that converts testosterone to estradiol, a type of estrogen. One study found that taking an estrogen blocker called an aromatase inhibitor while on testosterone therapy reduced estrogen and addressed low testosterone levels.
At what age do men start to lose testosterone?
In general, men begin to lose testosterone at a rate of 1%-2% each year after they turn 40. One study found that 20% of men over the age of 60 and 50% of those over the age of 80 experience lower levels of testosterone. However, not all people who experience age-related reductions in testosterone will have symptoms due to the change in testosterone levels.
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By Katie Wilkinson, MPH, MCHES
Katie Wilkinson is a public health professional with more than 10 years of experience supporting the health and well-being of people in the university setting. Her health literacy efforts have spanned many mediums in her professional career: from brochures and handouts to blogs, social media, and web content.
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