RESEARCH STARTER

Testosterone

Testosterone is a steroid hormone produced primarily in the testes of males and, in smaller amounts, by the ovaries in females. Males produce significantly more testosterone—about 5 to 10 times that of females—which plays a crucial role in developing male sex characteristics such as increased muscle mass, deepened voice, and facial hair during puberty. The hormone is often associated with traits like virility and physical strength, leading to a cultural fascination with its effects. In recent decades, testosterone-boosting products have surged in popularity, fueled by advertising that suggests low testosterone, or "low T," can lead to symptoms like decreased sex drive and energy levels. However, this marketing faces scrutiny from the medical community due to concerns over vague symptomatology, the accuracy of testosterone testing, and potential health risks associated with unsupervised testosterone use. It’s noted that testosterone levels fluctuate with age, physical activity, and emotional state, complicating the diagnosis of low testosterone. Additionally, studies indicate that many men seeking treatment may have normal testosterone levels, with factors like obesity affecting their perceived energy levels. Concerns about the side effects of testosterone supplements include increased risks of heart disease and prostate cancer, underscoring the importance of careful medical evaluation when considering testosterone therapy.

Full Article

Testosterone is a steroid hormone that is produced by males and females. Women produce only 5 to 10 percent as much testosterone as men. In males, the brain’s hypothalamus and pituitary gland signal the testes to manufacture testosterone, while in females, testosterone is produced in small amounts within the ovaries. In contrast to males, females produce larger quantities of estrogen. Testosterone and estrogen play important roles in the development of important biological differences between the sexes. During the embryonic stage, for example, testosterone is responsible for the development of the penis and testicles in male fetuses, and when a male reaches puberty, testosterone facilitates the onset of adult male sex characteristics, such as the development of increased muscle mass, production of sperm, deepening of the voice, the growth of facial and chest hair, and growth in the size of the penis and testicles.

Background

Given its reputation as the male sex hormone, testosterone has been associated with masculine traits such as virility, vigor, physical strength, aggression, and sexual performance in the public imagination for decades. Interest in testosterone among both the medical community and the general public can be traced to at least 1898, when French physician Charles-Edouard Brown-Sequard injected himself with liquid extracted from dog and guinea pig testicles, which he claimed increased his strength and improved his health. As medical technology advanced in the 1960s, doctors were able to determine testosterone levels through samples of an individual’s blood.

In August 1998, Major League Baseball star Mark McGwire of the St. Louis Cardinals publicly admitted that he had taken a testosterone-boosting supplement known as androstenedione for a year and a half. McGwire’s confession sparked intense media attention and controversy over the topic of testosterone enhancers, which was amplified by the fact that, at the time, McGwire was in the process of breaking Major League Baseball’s record for most home runs hit by a player in a season—thus fueling criticism from sports fans and journalists that androstenedione was essentially a diluted form of anabolic steroids. Despite being banned by the National Football League and international Olympic competition, androstenedione was at the time permitted by Major League Baseball on the grounds that the supplement did not directly build a user’s muscles, but only increased their levels of testosterone—which could only increase muscle mass and strength if a user also maintained a rigorous physical training regiment.

Also around this time, the Food and Drug Administration approved two drugs (Androderm in 1995; AndroGel in 2000) for use in the medical treatment of males with clinically low levels of testosterone, a condition known as hypogonadism. Hypogonadism can be caused by underdeveloped or damaged testicles, tumors, or the removal of a testicle during surgery for testicular cancer. Men with hypogonadism have testosterone levels lower than 250–300 nanograms per deciliter (ng/dL), which are measured by a blood test.

Overview

Since the late 1990s, the controversy surrounding testosterone-boosting supplements has intensified dramatically. Testosterone boosters or supplements are nonprescription products that do not contain testosterone. Such boosters or supplements are comprised of vitamins and minerals that supposedly help increase testosterone production but have not been evaluated by the Food and Drug Administration, may not be effective, and may cause side effects. Individuals considering supplementation should consult their healthcare provider about potential risks and benefits before taking boosters or supplements. The number of testosterone-enhancing products has considerably increased, and advertisements encouraging men to get tested to determine if they have decreased levels of testosterone, popularly referred to as "low T," have become commonplace on television, radio, and the internet. These advertisements describe symptoms of low testosterone to be a decreased sex drive, a loss of physical and/or mental energy, and feelings of lethargy, moodiness, and depression. The implication of such advertising campaigns is that such undesirable traits can be effectively treated through injections or applications of testosterone, promoting an image that testosterone supplements rejuvenate and reinvigorate middle-aged men. 

In 2002, sales for testosterone-boosting drugs and supplements reached $324 million in the United States, while sales approached $2 billion nationwide in 2012, according to the New York Times. A 2013 study published in the Medical Journal of Australia claimed a sharp increase in testosterone-boosting supplements in thirty-seven countries between 2000 and 2011. As reports revealed that the number of prescriptions for testosterone therapy continued to increase—with only a certain percentage of those individuals actually diagnosed with hypogonadism or tested for low testosterone levels—in 2016, the US Food and Drug Administration announced that it had approved a change to the labeling of prescription testosterone products, mandating that they must now include a warning that covers the risks associated with the abuse of and dependence on testosterone.

However, this upsurge in testosterone marketing and sales faced criticism from others within the scientific and medical communities. Major points of criticism included the vague and ambiguous symptoms that advertisements attribute to low testosterone, the questionable method by which such marketing companies and their allies in the medical industry use to determine a man’s testosterone level, and the potential for serious health risks to develop within men who take testosterone boosters but who do not actually have hypogonadism. Feelings of lethargy and depression, for example, can stem from a variety of psychological or physiological conditions and should not be viewed as stemming exclusively or primarily from decreased testosterone.

Furthermore, testosterone levels fluctuate with age and throughout the course of the day. Testosterone levels dramatically increase once a male reaches puberty, and a natural decrease in testosterone levels by 1–2 percent per year is normal in men over forty. The normal level of testosterone in adult males ranges from 300 to 1,000 ng/dL, and these levels vary considerably from man to man. Also, testosterone levels within an individual increase and decrease regularly as a result of factors such as sleep, exercise, and emotional state of mind. Testosterone levels are generally higher in the morning than at other times throughout the day for many men. To obtain a truly accurate measure of a man’s testosterone level, it would be necessary to conduct multiple tests over a period of time—similar to measuring one’s blood pressure accurately—instead of relying solely on a single measurement from one test.

In addition, the British Medical Journal conducted its own research, titled the "European Male Ageing Study," which measured testosterone levels and found that a mere 0.1 percent of men in their forties and 0.6 percent of men in their fifties would truly be diagnosed as having low testosterone under the routine medical criteria. Even half of men in their eighties have a testosterone level in the normal range for men in their forties and fifties. These results sharply contrasted with the "low T" advertising campaign launched by the manufacturer of AndroGel in 2008, which claimed that 13 million American men over 45 have low testosterone. Importantly, being overweight (which can reduce energy levels and sexual performance) may lead otherwise relatively healthy men to assume that they are suffering from decreased testosterone and to seek supplements. Kathleen Wyne of the Methodist Hospital Research Institute in Houston, Texas, claimed that many of the men she tested for "low T" actually have relatively normal testosterone levels but are overweight. Overweight men can naturally increase their testosterone levels by exercising and losing weight, since excess body weight can cause the body to convert some testosterone to estrogen.

During the 2020s, testosterone was increasingly being prescribed to women to manage menopausal symptoms and other age-related issues, as well as to men with low testosterone levels. In late 2025, the Food and Drug Administration (FDA) called for relaxed regulations on testosterone medications. Testosterone has been classified as a controlled substance due to its association as a performance-enhancing drug. The FDA stated that the medications, also known as testosterone replacement therapy (TRT), were safe, despite previous claims of increased risk of stroke, heart disease, and prostate cancer, and that many had been deprived of the therapy because of its regulatory status. At the same time, many men began seeking out testosterone medications, also known as testosterone replacement therapy (TRT), or testing for low testosterone because of increased visibility on social media. Many influencers began promoting the use of TRT, typically to younger men, and often alongside messaging about masculinity. A study from the University of Copenhagen, published in 2026, found that 72% of the social media posts promoting TRT also resulted in monetary gain through sponsorship and links and promotional codes to tests, supplements, and other medications.


Bibliography

Andriote, John-Manuel. "Should the Modern Man Be Taking Testosterone?" The Atlantic, 5 Apr. 2013, www.theatlantic.com/health/archive/2013/04/should-the-modern-man-be-taking-testosterone/274663/. Accessed 18 Feb. 2026.

Bendix, Aria. "FDA Panel Calls to Loosen Restrictions on Testosterone Replacement Therapy." NBC News, 10 Dec. 2025, www.nbcnews.com/health/mens-health/fda-panel-testosterone-replacement-therapy-rcna248053. Accessed 18 Feb. 2026.

Davey, Melissa. "‘Manosphere’ Influencers Pushing Testosterone Tests are Convincing Healthy Young Men There is Something Wrong with Them, Study Finds." The Guardian, 22 Jan. 2026, www.theguardian.com/society/2026/jan/22/manosphere-influencers-testosterone-tests-young-men. Accessed 18 Feb. 2026.

Dubowitz, Nicole, and Adriane Fugh-Berman. "Outside Opinion: Testosterone Treatments Are Dangerous for Men." Chicago Tribune, 24 Aug. 2021, www.chicagotribune.com/2013/09/15/outside-opinion-testosterone-treatments-are-dangerous-for-men/. Accessed 18 Feb. 2026.

"FDA Approves New Changes to Testosterone Labeling Regarding the Risks Associated with Abuse and Dependence of Testosterone and Other Anabolic Androgenic Steroids (AAS)." US Food and Drug Administration, 25 Oct. 2016, www.fda.gov/Drugs/DrugSafety/ucm526206.htm. Accessed 18 Feb. 2026.

Jones, Hugh. Testosterone Deficiency in Men. Oxford UP, 2013.

LeWine, Howard E. "Is Testosterone Therapy Safe? Take a Breath Before You Take the Plunge." Harvard Health Publishing, Harvard Medical School, 3 Apr. 2024, www.health.harvard.edu/mens-health/is-testosterone-therapy-safe-take-a-breath-before-you-take-the-plunge. Accessed 18 Feb. 2026.

"Mark McGwire’s Pep Pills." The New York Times, 27 Aug. 1998, www.nytimes.com/1998/08/27/opinion/mark-mcgwire-s-pep-pills.html. Accessed 18 Feb. 2026.

Rettner, Rachel. "What Is Testosterone?" LiveScience.com, 22 June 2017, www.livescience.com/38963-testosterone.html. Accessed 18 Feb. 2026.

Sellers, Alisha D. and Sian Ferguson. "Can Testosterone Supplements Improve Your Sex Drive?" Healthline, 13 Feb. 2023, www.healthline.com/health/low-testosterone/do-testosterone-supplements-work. Accessed 18 Feb. 2026.

Singer, Natasha. "Selling That New-Man Feeling." The New York Times, 23 Nov. 2013, www.nytimes.com/2013/11/24/business/selling-that-new-man-feeling.html. Accessed 18 Feb. 2026.

"Testosterone." MedlinePlus, NIH National Library of Medicine, 15 May 2025, medlineplus.gov/druginfo/meds/a619028.html. Accessed 18 Feb. 2026.

Thomas, Ian. "With Demand from Women for the Hormone Surging, Midi Health Introduces Testosterone Therapy." CNBC, 8 Dec. 2025, www.cnbc.com/2025/10/30/midi-health-to-offer-testosterone-therapy-as-demand-from-women-spikes.html. Accessed 18 Feb. 2026.

Vergel, Nelson. Testosterone: A Man’s Guide. Milestones, 2011.

Full Article

Testosterone is a steroid hormone that is produced by males and females. Women produce only 5 to 10 percent as much testosterone as men. In males, the brain’s hypothalamus and pituitary gland signal the testes to manufacture testosterone, while in females, testosterone is produced in small amounts within the ovaries. In contrast to males, females produce larger quantities of estrogen. Testosterone and estrogen play important roles in the development of important biological differences between the sexes. During the embryonic stage, for example, testosterone is responsible for the development of the penis and testicles in male fetuses, and when a male reaches puberty, testosterone facilitates the onset of adult male sex characteristics, such as the development of increased muscle mass, production of sperm, deepening of the voice, the growth of facial and chest hair, and growth in the size of the penis and testicles.

Background

Given its reputation as the male sex hormone, testosterone has been associated with masculine traits such as virility, vigor, physical strength, aggression, and sexual performance in the public imagination for decades. Interest in testosterone among both the medical community and the general public can be traced to at least 1898, when French physician Charles-Edouard Brown-Sequard injected himself with liquid extracted from dog and guinea pig testicles, which he claimed increased his strength and improved his health. As medical technology advanced in the 1960s, doctors were able to determine testosterone levels through samples of an individual’s blood.

In August 1998, Major League Baseball star Mark McGwire of the St. Louis Cardinals publicly admitted that he had taken a testosterone-boosting supplement known as androstenedione for a year and a half. McGwire’s confession sparked intense media attention and controversy over the topic of testosterone enhancers, which was amplified by the fact that, at the time, McGwire was in the process of breaking Major League Baseball’s record for most home runs hit by a player in a season—thus fueling criticism from sports fans and journalists that androstenedione was essentially a diluted form of anabolic steroids. Despite being banned by the National Football League and international Olympic competition, androstenedione was at the time permitted by Major League Baseball on the grounds that the supplement did not directly build a user’s muscles, but only increased their levels of testosterone—which could only increase muscle mass and strength if a user also maintained a rigorous physical training regiment.

Also around this time, the Food and Drug Administration approved two drugs (Androderm in 1995; AndroGel in 2000) for use in the medical treatment of males with clinically low levels of testosterone, a condition known as hypogonadism. Hypogonadism can be caused by underdeveloped or damaged testicles, tumors, or the removal of a testicle during surgery for testicular cancer. Men with hypogonadism have testosterone levels lower than 250–300 nanograms per deciliter (ng/dL), which are measured by a blood test.

Overview

Since the late 1990s, the controversy surrounding testosterone-boosting supplements has intensified dramatically. Testosterone boosters or supplements are nonprescription products that do not contain testosterone. Such boosters or supplements are comprised of vitamins and minerals that supposedly help increase testosterone production but have not been evaluated by the Food and Drug Administration, may not be effective, and may cause side effects. Individuals considering supplementation should consult their healthcare provider about potential risks and benefits before taking boosters or supplements. The number of testosterone-enhancing products has considerably increased, and advertisements encouraging men to get tested to determine if they have decreased levels of testosterone, popularly referred to as "low T," have become commonplace on television, radio, and the internet. These advertisements describe symptoms of low testosterone to be a decreased sex drive, a loss of physical and/or mental energy, and feelings of lethargy, moodiness, and depression. The implication of such advertising campaigns is that such undesirable traits can be effectively treated through injections or applications of testosterone, promoting an image that testosterone supplements rejuvenate and reinvigorate middle-aged men. 

In 2002, sales for testosterone-boosting drugs and supplements reached $324 million in the United States, while sales approached $2 billion nationwide in 2012, according to the New York Times. A 2013 study published in the Medical Journal of Australia claimed a sharp increase in testosterone-boosting supplements in thirty-seven countries between 2000 and 2011. As reports revealed that the number of prescriptions for testosterone therapy continued to increase—with only a certain percentage of those individuals actually diagnosed with hypogonadism or tested for low testosterone levels—in 2016, the US Food and Drug Administration announced that it had approved a change to the labeling of prescription testosterone products, mandating that they must now include a warning that covers the risks associated with the abuse of and dependence on testosterone.

However, this upsurge in testosterone marketing and sales faced criticism from others within the scientific and medical communities. Major points of criticism included the vague and ambiguous symptoms that advertisements attribute to low testosterone, the questionable method by which such marketing companies and their allies in the medical industry use to determine a man’s testosterone level, and the potential for serious health risks to develop within men who take testosterone boosters but who do not actually have hypogonadism. Feelings of lethargy and depression, for example, can stem from a variety of psychological or physiological conditions and should not be viewed as stemming exclusively or primarily from decreased testosterone.

Furthermore, testosterone levels fluctuate with age and throughout the course of the day. Testosterone levels dramatically increase once a male reaches puberty, and a natural decrease in testosterone levels by 1–2 percent per year is normal in men over forty. The normal level of testosterone in adult males ranges from 300 to 1,000 ng/dL, and these levels vary considerably from man to man. Also, testosterone levels within an individual increase and decrease regularly as a result of factors such as sleep, exercise, and emotional state of mind. Testosterone levels are generally higher in the morning than at other times throughout the day for many men. To obtain a truly accurate measure of a man’s testosterone level, it would be necessary to conduct multiple tests over a period of time—similar to measuring one’s blood pressure accurately—instead of relying solely on a single measurement from one test.

In addition, the British Medical Journal conducted its own research, titled the "European Male Ageing Study," which measured testosterone levels and found that a mere 0.1 percent of men in their forties and 0.6 percent of men in their fifties would truly be diagnosed as having low testosterone under the routine medical criteria. Even half of men in their eighties have a testosterone level in the normal range for men in their forties and fifties. These results sharply contrasted with the "low T" advertising campaign launched by the manufacturer of AndroGel in 2008, which claimed that 13 million American men over 45 have low testosterone. Importantly, being overweight (which can reduce energy levels and sexual performance) may lead otherwise relatively healthy men to assume that they are suffering from decreased testosterone and to seek supplements. Kathleen Wyne of the Methodist Hospital Research Institute in Houston, Texas, claimed that many of the men she tested for "low T" actually have relatively normal testosterone levels but are overweight. Overweight men can naturally increase their testosterone levels by exercising and losing weight, since excess body weight can cause the body to convert some testosterone to estrogen.

During the 2020s, testosterone was increasingly being prescribed to women to manage menopausal symptoms and other age-related issues, as well as to men with low testosterone levels. In late 2025, the Food and Drug Administration (FDA) called for relaxed regulations on testosterone medications. Testosterone has been classified as a controlled substance due to its association as a performance-enhancing drug. The FDA stated that the medications, also known as testosterone replacement therapy (TRT), were safe, despite previous claims of increased risk of stroke, heart disease, and prostate cancer, and that many had been deprived of the therapy because of its regulatory status. At the same time, many men began seeking out testosterone medications, also known as testosterone replacement therapy (TRT), or testing for low testosterone because of increased visibility on social media. Many influencers began promoting the use of TRT, typically to younger men, and often alongside messaging about masculinity. A study from the University of Copenhagen, published in 2026, found that 72% of the social media posts promoting TRT also resulted in monetary gain through sponsorship and links and promotional codes to tests, supplements, and other medications.


Bibliography

Andriote, John-Manuel. "Should the Modern Man Be Taking Testosterone?" The Atlantic, 5 Apr. 2013, www.theatlantic.com/health/archive/2013/04/should-the-modern-man-be-taking-testosterone/274663/. Accessed 18 Feb. 2026.

Bendix, Aria. "FDA Panel Calls to Loosen Restrictions on Testosterone Replacement Therapy." NBC News, 10 Dec. 2025, www.nbcnews.com/health/mens-health/fda-panel-testosterone-replacement-therapy-rcna248053. Accessed 18 Feb. 2026.

Davey, Melissa. "‘Manosphere’ Influencers Pushing Testosterone Tests are Convincing Healthy Young Men There is Something Wrong with Them, Study Finds." The Guardian, 22 Jan. 2026, www.theguardian.com/society/2026/jan/22/manosphere-influencers-testosterone-tests-young-men. Accessed 18 Feb. 2026.

Dubowitz, Nicole, and Adriane Fugh-Berman. "Outside Opinion: Testosterone Treatments Are Dangerous for Men." Chicago Tribune, 24 Aug. 2021, www.chicagotribune.com/2013/09/15/outside-opinion-testosterone-treatments-are-dangerous-for-men/. Accessed 18 Feb. 2026.

"FDA Approves New Changes to Testosterone Labeling Regarding the Risks Associated with Abuse and Dependence of Testosterone and Other Anabolic Androgenic Steroids (AAS)." US Food and Drug Administration, 25 Oct. 2016, www.fda.gov/Drugs/DrugSafety/ucm526206.htm. Accessed 18 Feb. 2026.

Jones, Hugh. Testosterone Deficiency in Men. Oxford UP, 2013.

LeWine, Howard E. "Is Testosterone Therapy Safe? Take a Breath Before You Take the Plunge." Harvard Health Publishing, Harvard Medical School, 3 Apr. 2024, www.health.harvard.edu/mens-health/is-testosterone-therapy-safe-take-a-breath-before-you-take-the-plunge. Accessed 18 Feb. 2026.

"Mark McGwire’s Pep Pills." The New York Times, 27 Aug. 1998, www.nytimes.com/1998/08/27/opinion/mark-mcgwire-s-pep-pills.html. Accessed 18 Feb. 2026.

Rettner, Rachel. "What Is Testosterone?" LiveScience.com, 22 June 2017, www.livescience.com/38963-testosterone.html. Accessed 18 Feb. 2026.

Sellers, Alisha D. and Sian Ferguson. "Can Testosterone Supplements Improve Your Sex Drive?" Healthline, 13 Feb. 2023, www.healthline.com/health/low-testosterone/do-testosterone-supplements-work. Accessed 18 Feb. 2026.

Singer, Natasha. "Selling That New-Man Feeling." The New York Times, 23 Nov. 2013, www.nytimes.com/2013/11/24/business/selling-that-new-man-feeling.html. Accessed 18 Feb. 2026.

"Testosterone." MedlinePlus, NIH National Library of Medicine, 15 May 2025, medlineplus.gov/druginfo/meds/a619028.html. Accessed 18 Feb. 2026.

Thomas, Ian. "With Demand from Women for the Hormone Surging, Midi Health Introduces Testosterone Therapy." CNBC, 8 Dec. 2025, www.cnbc.com/2025/10/30/midi-health-to-offer-testosterone-therapy-as-demand-from-women-spikes.html. Accessed 18 Feb. 2026.

Vergel, Nelson. Testosterone: A Man’s Guide. Milestones, 2011.

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