10 Effects Testosterone Has on Your Health

December 08, 2021

Written by Andrea Vale

Historically, testosterone has been associated with masculinity and traditionally “manly” traits. Having high levels of testosterone was shorthand for perceived aggression, strength, and libido. But testosterone plays a significant role in everyone’s general health and function, men and women alike. Indeed, testosterone plays just as important a role in ovarian function as it does in male reproductive development.

Having abnormally high levels of testosterone is not particularly common, and it most typically occurs in athletes who have taken steroids or hormones to boost athleticism. Low levels of testosterone, however, are a natural side effect of aging, with approximately 20% of men over 60, to 50% of men over 80, dealing with low testosterone. Additionally, injuries, radiation-focused medical treatments, and changes to the pituitary gland can all cause testosterone levels to drop.

Need a testosterone solution?

Elevate your vitality and supercharge your life with Rex MD.

Get Started

What is a "normal" testosterone level?

For men, testosterone generally lands between 300 and 1050 ng/dL (nanograms per deciliter), and anything less than 300 is considered a sign of hypogonadism. For women, testosterone is generally around 25-60 ng/dL through her adult life.

Compare this to men's roughly 2-5 ng/dL of estrogen through adulthood, and women's estrogen levels of around 20 ng/dL.

"Interestingly, women in fact have 'more' testosterone than estrogen in their blood at any given time," says Dr. Banita Sehgal. "This apples to oranges comparison leaves out the complexity of our hormonal make-up, of course, and it's the ratio that differentiates men and women here. Estrogen is just so powerful."

Transmasculine nonbinary people and transgender men may use testosterone to help promote traditionally masculine traits and body types too. In addition to the other effects testosterone has on the body, trans individuals who supplement the hormone have a decreased risk of gender dysphoria, depression, and anxiety as hormone replacement therapy (HRT) helps them feel more like themselves. Taking testosterone consistently can lead to facial and body hair growth, lowered vocal pitch, increased muscle-to-fat ratio, diminished or an end to menstruation, and other health conditions cisgender men experience.

Overall, testosterone levels vary widely from year to year — and even from hour to hour. This can affect a broad range of internal and external physiological functions. Testosterone manipulates everything from metabolism and weight, to hair and skin quality, concentration, and mood. Over time, testosterone abnormalities can have serious effects on one's bones and heart too.

Rex MD compiled a list of 10 effects that testosterone has on your health, using research from scientific journals and health publications. Read on to find out the detriments — and occasional benefits — of having too much or too little testosterone flowing through your body.

Your Likeliness To Build Muscle

Testosterone can significantly affect the body’s ability to gain or lose muscle due to particular biological reactions. Once testosterone is present throughout the body, it naturally binds to triggers on muscle cells, which catalyze those cells to increase protein production. It also promotes the spread of neurotransmitters throughout the body, which stimulate tissue growth and growth hormones. This results in increased muscle mass. Consequently, low testosterone is associated with muscle loss, while high testosterone generally causes the opposite.

Behaviors, from Competition to Aggression

Variations in energy, mood, and confidence are all affected by testosterone levels. Although testosterone levels can cause some behaviors, testosterone levels can also increase as a result of certain activities. For instance, sexual or competitive activities can lower or raise testosterone levels, while high testosterone may result in abnormally high aggression, irritability, libido, and mood swings, as well as impaired decision-making abilities. 

Inversely, low testosterone can cause low confidence, listlessness, a lack of concentration, low energy, and depression. This is particularly the case for transmasculine people and transgender men who may also experience gender dysphoria on top of the other symptoms associated with lower testosterone levels.

Notably, it’s difficult to separate these behavioral phenomena from the multiple biological and environmental influences simultaneously at play, so one should be cautious about attributing a behavioral change exclusively to testosterone levels.

Bone Density

Testosterone’s effects on bone density are due to its interactions with bone marrow, during which it can spur marrow to produce red blood cells at higher rates. Low testosterone levels can weaken bone density, causing bones to be brittle and weak. This puts those with testosterone deficiencies at higher risk of fractures and breaks. Consequently, bone strength can sometimes be increased through raising testosterone. For instance, someone suffering from osteoporosis may take a testosterone replacement alongside other treatments.

Libido

Testosterone’s relationship to libido is a two-way street: while testosterone can affect sexual performance, sexual activity can also affect testosterone levels. Low testosterone is associated with low libido and erectile dysfunction—however, extended periods of sexual inactivity can also lead to lowered testosterone. Higher levels of testosterone can increase libido, though (somewhat counterintuitively) also lower sperm counts. Changes in libido are not exclusive to men: women with a testosterone deficiency can also suffer from low sexual desire. The effects of testosterone on libido in women becomes less clear once women have been through menopause. About 70% of trans men reported an increase in sexual desire after beginning to supplement testosterone, while about 30% rarely or never felt sexual desire.

Hair Growth

Testosterone initially affects hair growth via its role at the onset of reproductive development, causing hair to sprout on the face, underarms, and genitals of puberty-age males. In transmaculine people and transgender men taking testosterone, the distribution of hair growth shifts, leading to increased facial and body hair growth and increased risk of male pattern baldness. Transfeminine people and transgender women on HRT, conversely, experience less facial and body hair growth and density due to increased estrogen levels, in addition to blocking the production of testosterone. Later in life, these effects continue to be noticeable. As men approach old age and their testosterone levels naturally fall, they may experience hair loss on both the head and body. Women who experience abnormally high testosterone levels may notice hair growing on their faces. This is particularly true of women with polycystic ovary syndrome (PCOS), which results in spiked testosterone levels.

How You Burn Fat

Metabolism can speed up or slow down due to testosterone levels. Testosterone regulates metabolism, and a healthy testosterone balance allows the body to avoid burning too much or too little fat. Those with high testosterone levels may notice weight gain, and trans individuals on HRT typically gain weight as well. This is due to a variety of factors that may not actually indicate an accumulation of fat, including fluid retention and increased muscle mass. Because testosterone increases muscle mass, however, it may result in fat loss, as muscle-building increase one’s metabolic rate, both at rest and during exercise.

Red Blood Cell Production

Generally, higher levels of testosterone cause an increase in the production of red blood cells. During a 2014 study, sixty 60-year-old men received either testosterone treatments or a placebo, with their resulting iron metabolism and red blood cell levels compared. Results indicated that increased testosterone levels spurred the production of red blood cells, with hemoglobin levels in treatment recipients increasing by 8%. Consequently, testosterone replacement therapy may have benefits for the heart, cholesterol, and blood pressure, though these effects are still being confirmed. Results of HRT's impact on transgender individuals' cardiovascular health—either blocking or increasing the production of testosterone—is also inconclusive.

Skin Conditions

Testosterone can cause skin to be quite reactive, depending on levels. Those with high levels of testosterone may experience acne breakouts. In some cases, testosterone-deficient individuals may receive replacements via patches or creams, in which case testosterone’s direct application may result in irritated skin. Cisgender women with abnormally high levels of testosterone may develop dark patches of skin. In these cases, hormone-blocking diuretics may be able to mitigate symptoms. Transmasculine people and trans men also face these health risks when on HRT, and transfeminine people and trans women may also need to change up their skincare routines when on HRT.

Reproductive System Growth and Development

Testosterone is directly linked to reproductive development in cisgender men. Testosterone levels begin to affect an embryo while it is still in the uterus, triggering the initial formation of male genitals. At the onset of puberty, levels of the hormone rise, causing the growth of the testicles and penis and the production of sperm. Cisgender men with a testosterone deficiency around this age may not experience these developments. 

Despite connotations as an indicator of masculinization, testosterone also plays an important role in female development. The right levels of estrogen and testosterone ensure that the ovaries function properly.

For some trans individuals, taking puberty blockers may help them better understand their gender identity whether they may want to pursue HRT in the future. This will make transitioning easier later in life as they do not have to reverse the effects the body goes through during adolescence, namely to their reproductive system. If a person decides to go through with HRT at any stage in life, decreasing testosterone will result in lower sperm count; however, HRT does not block sperm count entirely, meaning trans people with increasing estrogen can still be fertile. For transmasculine people and trans men, testosterone supplements can end menstruation and similarly decrease fertility. One recent study found that trans masculine people and trans men can stop supplementing testosterone for four months and still see similar egg yields to cisgender women. For the sake of fertility, it’s recommended that trans people either freeze their sperm or eggs to better guarantee the possibility of having their own children in the future.

Sleep Patterns

Both irregularly high and low levels of testosterone can upset the quality and quantity of hours spent sleeping. Conversely, regular uninterrupted sleep is necessary to maintain healthy levels of testosterone in the body. Those with irregular levels of testosterone may be more vulnerable to sleep-related disorders. During a 2003 study, 17 men over 60 years old were observed after receiving regular injections of testosterone. Among other effects, it was found that the hormone disrupted sleep, resulting in spells of sleep apnea, disturbed breathing patterns, and fewer hours slept overall.

How Can Rex MD Help?

Balanced testosterone levels are a key factor in men’s health. If you are struggling with fatigue, low libido, decreased muscle mass, or a decline in overall mood, Rex MD is here to help.

With the Rex MD TestoRX program, you’ll have access to testosterone replacement therapies and other testosterone solutions that can help restore your vitality and get you back to feeling like yourself again.

To find out if the program is right for you, just answer some about your symptoms and medical history. Your provider will order lab work for you to help determine if you’re eligible for testosterone injections or another treatment option.

Then, you’ll be able to schedule a virtual call with the Rex MD care team to further discuss your results, eligibility, and which treatment option would be most suitable for you, if any.

Get started today to feel good again, both physically and emotionally.