Increased physical stamina. “Facility of intellectual labour.” A longer jet of urine. These were some of the effects that Charles-Édouard Brown-Séquard, a French physiologist, reported to a Société de Biologie of Paris meeting in 1889. He had been injecting himself with a liquid made of pulverized animal testicles in an attempt to reverse “the most troublesome miseries of advanced life.” He took 10 injections over three weeks, and experienced “radical change” for about a month after.
“It is hardly possible to explain the effects I have observed on myself otherwise than by admitting that the liquid injected possesses the power of increasing the strength of many parts of the human organism,” he told the gathering.
A large number of physicians followed his lead, injecting patients with animal testicular fluids, and the so-called Brown-Séquard Elixir became a sensation. Thousands of men, including Pittsburgh baseball pitcher James “Pud” Galvin, an early dabbler in performance-enhancing drugs, felt their virility was restored. Newspapers reported on patients getting rid of their crutches immediately after injections, and in one case a man of 70, suffering from rheumatism, started “dancing and jumping about like a boy since the treatment.”
Sounds a lot like testosterone therapy. Except, there was barely any testosterone — in fact, barely anything at all — in the injections. The results, studies have confirmed, were placebo.
But there is good reason for Brown-Séquard’s injections to make one think of the mushrooming industry of male health clinics trumpeting testosterone therapy. They, too, promise men results including “increased stamina and endurance,” “improved cognitive abilities,” and “increased sense of well-being” — for many men, they appear to embody the latest iteration of the elusive fountain of male youth.
Unlike Brown-Séquard’s elixir though, testosterone is not nothing. And the millions of men who report great benefits from testosterone supplementation, powering a market projected to reach $2.5 billion, can’t all be experiencing placebo effects. While the hormone is sometimes prescribed to men who don’t need it, there’s more to the proliferation of prescription-happy men’s health clinics than reckless medical practices and influencer hype, say physicians who understand its value for some men. It’s also a sign of the health care system’s lack of regard for male sexual hormones and their role in health; many primary care doctors learned little about hormone therapy in medical school and haven’t kept up with the research on testosterone.
That research shows that when the symptoms patients complain about — be it fatigue, low libido, or mood disorders — are caused by low testosterone, replacement therapy through gels, pellets, or more often, injections is typically successful in alleviating their symptoms. And with medical guidance and monitoring, side effects, which include testicular shrinkage, reduced sperm production, and breast tissue enlargement, can be controlled.
“We tend to talk about the lengths that men go to as if this is worthy of ridicule, that men would undergo procedures or take elixirs or whatever it is, all seeking to preserve their youth,” said Abraham Morgentaler, a urologist who has been studying testosterone deficiency since the 1970s, and is currently a Blavatnik faculty fellow in health and longevity at Harvard Medical School.
Men who are feeling fatigued, depressed, and generally unwell may find that mainstream medical practices often don’t as much as acknowledge their symptoms as worthy of investigation, let alone engage with the hypothesis low testosterone may be at play. Major physician groups also give conflicting guidance on when testosterone levels are low and therapy is warranted. And so, men look elsewhere.
Where mainstream medicine falls short
Peek into any of the online forums dedicated to testosterone replacement — typically, rabbit hole after rabbit hole of studies, lab results, injection routines, treatment protocols — and you will easily find patients questioning their primary care physicians’ knowledge of testosterone therapy, and ready to bypass their advice for the tempting lure of a testosterone clinic.
“Doctors didn’t dive into this at all — and this includes endocrinologists,” said Garrett Soames, a physician assistant and co-founder and chief medical officer of Alpha MD, an online clinic providing testosterone therapy as a monthly subscription. Soames is proud to be on testosterone himself.
Morgentaler said “the online comments that the doctors don’t know anything about [testosterone] are accurate, and I can’t tell you how often in my career I’ve had patients come see me who’ve gone from doctor to doctor and [they] have been told that testosterone deficiency and testosterone therapy represent fringe medicine … Many of those patients are deficient in testosterone and respond very nicely to treatment.”
Several patients who eventually started testosterone therapy told STAT they felt that their doctors weren’t familiar with testosterone replacement, or were unwilling to support them and monitor their results. “My primary care doctors — I had two because I moved — both said the same thing: ‘You don’t really need to test that, you’re fine’,” said Dan B., 43, who had complained about feeling lethargic and in a low mood. (Like many of the men interviewed for this article, he asked STAT not to use his full name to protect his privacy.)
One physician told him the absence of erectile dysfunction was proof he was not testosterone deficient, though that isn’t a diagnostic criteria. He eventually got his total testosterone tested anyway, finding levels around 300 nanograms per deciliter — barely above the cutoff for hypogonadism (testosterone deficiency, in endocrinology-speak), and at a level that, combined with symptoms of fatigue, could justify testosterone therapy.
Now that his testosterone is higher, he says he has more energy and feels sharper: “I feel more focused when I’m doing things, and you just have an overall better sense of well-being. You feel like your emotional state is more even-keeled.”
Similarly, when his online research prompted J.S., a 72-year-old man living in Seattle, to ask his primary care physician about testosterone testing because of fatigue, “his follow-up questions proved to me that he had no idea whatsoever about testosterone therapy,” he said. He eventually did find he had low levels of testosterone, and has been in treatment for about a year. “To simply say that my strength and endurance have improved considerably does not communicate the extent of the difference,” he said. “I simply feel like a younger version of myself.”
It’s T time: why testosterone has become so popular
The amount of online chatter about testosterone is echoed in doctors’ offices. Providers report seeing many more patients who are inquiring about their testosterone levels, and diagnosing more with hypogonadism. And though the overall number of prescriptions for testosterone remains small — about 2 in 100,000 prescriptions, according to data from GoodRx — the scripts for testosterone cypionate, the injectable form, doubled between 2019 and 2025.
The rise in patients presenting with low testosterone is due to many factors, said John Mulhall, director of sexual and reproductive medicine at Memorial Sloan Kettering Cancer Center and chair of the American Urology Association testosterone guidelines committee, including more awareness of hypogonadism symptoms and an established decline in testosterone levels in men that’s yet to be attributed to a clear cause.
Plus in the U.S., “there is incredible availability of testosterone products,” he said, noting there are 17 on his hospital’s list. “So the utilization of testosterone therapy in America is far greater than in other places in the world, including continental Europe.”
This isn’t the first time testosterone treatment has hit the zeitgeist. The recent trend mirrors the sudden popularity testosterone in the aughts after the launch of AndroGel, the first testosterone product to receive Food and Drug Administration approval, in 2000. In 2002, Solvay Pharmaceuticals, the company behind AndroGel (which was later sold to AbbVie), struck marketing gold: It rebranded andropause (the decline of testosterone due to age) with a grabbier label — “low T” — and invested in direct-to-consumer advertising and awareness campaigns.
Sales skyrocketed despite the FDA calling for caution and asking that all testosterone products carry a warning about increased risk of cardiovascular events. (The warning was removed earlier this year after the large TRAVERSE trial provided evidence that there is no added risk of those conditions, even as there can be other concerning side effects, especially for younger people, such as infertility.)
Things cooled down with T for a few years, until something else pushed the market beyond any previous records: Covid. Or rather, the widespread adoption of telemedicine. Testosterone is a controlled substance, though the limitations on who can prescribe it in person are pretty loose: Most health care professionals, including mid-level practitioners such as midwives or physician assistants, can do so, as long as they’re licensed by the Drug Enforcement Administration.
Remote prescriptions are subject to stricter rules, and are allowed only after at least one in-person visit, but those restrictions have been relaxed since the pandemic, and exceptions have been renewed four times since the end of the emergency period. Currently, they are set to expire in December 2026.
And the internet isn’t just the place to get testosterone: It is also where an army of male health influencers tout its benefits. Podcaster Joe Rogan has been broadcasting the “big difference” it made in his life to his millions of followers for years. Health secretary Robert F. Kennedy Jr. has listed testosterone shots as part of his anti-aging protocol, and celebrities including Robbie Williams, Josh Duhamel, and Alan Ritchson have discussed their use of testosterone treatment.
A toe dip into TikTok or other social media will surface a long list of influencer accounts discussing testosterone benefits and testosterone boosting techniques of various levels of scientific substance: “Low testosterone is the cause of 99% of male problems,” says one influencer in a popular video. “Up your egg intake, however many eggs you’re eating now, times ten.”
“Men are looking for answers to why they have fatigue, why they have low libido, why they have erectile dysfunction, and the narrative has become that testosterone is the root cause of all of these symptoms, which it usually isn’t,” said Michael Irwig, an endocrinologist at Beth Israel Deaconess Medical Center who specializes in androgens.
But if the people going viral with their T content may be misguided and misguiding, the effects of their presence is being felt in the number of men who have become aware of testosterone treatment.
Diagnosing testosterone deficiency: It’s complicated
For men who are testosterone curious — because they experience some of the symptoms of low testosterone, or have encountered online content promoting T — learning their testosterone levels, and potentially starting treatment, is not straightforward.
The diagnosis and treatment of testosterone deficiency requires two elements: the presence of symptoms, and low blood values of the hormone. This is where some of the trouble begins. The symptoms can be plentiful — fatigue, lack of libido, brain fog, low mood, erectile dysfunction — but they are hard to irrefutably attribute to lack of testosterone.
For one, the cut-off levels for blood tests vary: For the American Urological Association, total testosterone values below 300 ng/dL indicate testosterone deficiency; for the American Endocrine Society, hypogonadism is defined by total testosterone values below 264 ng/dL; and for the European Association of Urology, the cut-off is 350 ng/dL (although there isn’t consensus in Europe, either).
To complicate things, testosterone levels can vary dramatically during the course of a day, or from one day to the next. And even someone who does not suffer from testosterone deficiency may dip below the threshold from time to time.
So, if someone has symptoms that could be attributed to low testosterone, when are they a good candidate for testosterone treatment? Is someone whose testosterone hovers just above the cut-off, with levels that would not be considered sufficient had they been the result of testosterone treatment, a good candidate? Are aging men, who lose about 1% of total testosterone every year after 30, fatigued by decades of life or in need of a testosterone top up? Is a man whose relative testosterone level has gone down significantly, while staying within the normal range, going to benefit from testosterone injections?
“I very much am against treating lab values,” said Larry Lipshultz, professor of urology at Baylor College of Medicine in Houston. By way of illustration, he mentioned a patient of his who is an athlete and in treatment for low testosterone. Due to regulation, he is only allowed a limited dose, even though it is not sufficient to ease his symptoms, and while his levels are fine based on lab results alone, as a 6-foot-8, 350-pound man, Lipshultz believes he would greatly benefit from higher testosterone supplementation. “A good physician is going to evaluate not only the lab values but the patient’s symptoms,” he said.
There is yet another tricky aspect to interpreting test results. Two testosterone metrics are typically measured in the blood: total testosterone, which includes all testosterone bound to proteins, which isn’t available to the body until it is released; and free testosterone, the active form.
“The endocrinology community has not yet fully embraced this idea that free testosterone is more important than total testosterone, and yet the evidence, both clinically and scientifically, is clear,” said Morgentaler, pointing to published literature on the subject, including studies finding hypogonadism in men with sufficient total testosterone, and that symptoms of low testosterone correlate more with low free than low total testosterone.
This isn’t beyond debate, however. “Free testosterone can be useful in certain scenarios but most of the time if a serum total testosterone is normal, this is a good rule-out test,” said Raul Herrera Pena, an endocrinologist at the University of Minnesota. Further, said Irwig, “some of the assays for free testosterone are not that accurate.”
Between different measures of testosterone, and a wide variety of assays, identifying who would benefit from testosterone treatment can be challenging, and primary care physicians may not feel comfortable making the diagnosis or prescribing treatment. There are, too, lingering misconceptions about the safety of testosterone therapy, including now-dispelled fears of cardiovascular events and testicular and prostate cancer, as well as hesitancy to prescribe controlled substances.
Urologists and endocrinologists are better positioned to identify and treat patients who could benefit, but approaches vary there, too. For instance, urologists may be more inclined than endocrinologists to try testosterone even when the test results don’t meet the exact cut-off levels, because “we treat often symptoms that may not have an associated blood test,” such as erectile dysfunction, said Morgentaler, himself a urologist. Endocrinologists, on the other hand, may be more focused on balancing hormonal levels, and less inclined to prescribe medication.
Different doctors may have different philosophies of treatment, too, which comes into play especially when low testosterone is more of a symptom. For instance, if a man who has obesity feels fatigued, or has low libido, his doctor may well find that his testosterone levels are low. But they may want to address the obesity first — which is likely the cause of low testosterone — rather than immediately prescribe testosterone.
“If it’s something that is treated with weight loss, that should be done first,” said Adrian Dobs, an endocrinologist and professor of medicine and oncology at Johns Hopkins University. “There may be a reason to give with testosterone, but I think you just have to be careful not to jump on it.”
Others have a different approach. “I don’t want to be a purist about saying no, I won’t give you testosterone because you’re overweight and that’s the cause,” said Lipshultz. Morgenthaler said it’s moralizing to not give patients testosterone until they make lifestyle changes. “I will treat men even if they are obese and not working out,” he said. “Everyone who’s overweight knows he’s overweight and is supposed to diet and exercise. There’s no value in my being the 27th person to tell them this.”
It’s no wonder, then, that many men are embracing a simpler alternative.
‘Click here for testosterone’
Enter testosterone clinics — providers focused on male health, often with evocative names such as DudeMeds, MaleExcel, Maximus, Titan — where the pendulum has swung all the way to the other side. Their patients typically can bypass traditional physician or specialist visits. A potential customer may get their testosterone levels tested through at-home tests, or sometimes not at all, and are often offered a prescription even if their lab values don’t align with established diagnostic criteria. Testosterone is then delivered to their home — for a monthly fee ranging from under $100 to several hundred dollars a month.
Alpha MD, one such clinic, serves many thousands of patients around the country through about 10 providers, who Soames says all take testosterone themselves. “We all kind of have been through the runaround. We’ve all experienced being denied by our doctors,” he said. Typically, Alpha MD patients, too, have been turned away from their physicians, who either didn’t think they needed their testosterone levels tested, or found them to be sufficient.
“In our practice, we turn away or deny about 10% of patients,” he said, usually ones whose testosterone levels are already at the high end of the range and are more likely to experience concerning side effects of excess testosterone, in particular erythrocytosis — increased red cell count.
Their business is booming, and so is their industry overall. A 2023 study of men’s online health clinics providing testosterone therapy identified 223 online clinics, of which a third had multiple physical locations, too. The numbers have only gone up. A reported 325 new clinics with several locations and online presence have opened since early 2024, and although there is no unified registry of clinics offering testosterone, the total number may well be in the thousands. And now, some of the bigger players in telehealth prescribing — Ro, Hims, Hone — have entered the field, or are planning to.
To be sure, online clinics aren’t the ideal solution to the challenges of getting testosterone. Lack of proper oversight, a bias toward prescribing (as it’s the basis of the business model), even to men who may not need it, and inadequate education about possible side effects worry experts and make many patients uneasy, though they are willing to take the risk to find treatment.
Soames says his clinic is changing lives, the way testosterone changed his, and claims its providers — who are primarily not physicians — have better knowledge and understanding of the workings of testosterone than most doctors. For instance, he said, one criteria they use to decide whether a patient would benefit from testosterone is “relative hypogonadism,” which means someone’s testosterone is in the normal range, but lower than what it used to be.
Many experts in hormonal health are skeptical of such an approach because testosterone levels fluctuate greatly even in a single day, so it would be hard to establish a baseline. Unsurprisingly, these experts are more broadly critical of online testosterone clinics.
“There are a lot of clinics that are just out to make money,” said Irwig. “They’re not taking good histories, they’re often not even doing physical exams, they’re not even counseling patients about possible side effects … they’re just eager to enroll them in programs where they’re selling them testosterone.” He added that he knows of clinics that tell men a testosterone level of 400 or 500 ng/dL is low when it’s not. Men with such levels who report feeling better after testosterone therapy are probably experiencing the placebo effect, he said.
Patients also lament the minimal oversight at some clinics. As one wrote in an online review: “My only phone call with the physician to begin my TRT last[ed] about 20 seconds. It went like this: ‘I’ve seen your blood work and you qualify for TRT. You can go online and place your order. Any questions?’ Not the experience I was hoping for.”
Herrera Pena, the Minnesota endocrinologist, said he is especially worried by the lack of thorough lab workup to carefully diagnose testosterone deficiency, as well as identify any underlying cause of such deficiency. Further, he said, when patients who have been going to online clinics come to him, they often use higher doses than recommended in standard medical practice. “I always tell people, be careful when you’re going to a cash pay clinic, just be careful on what they’re selling to you.”
There are significant health risks, too, beyond red cell count. They include infertility, which is especially concerning for younger men. External testosterone reduces the body’s own production of the hormone, which can lead to low sperm count. Reversing these effects can take several months to more than a year.
Asima Ahmad, a reproductive endocrinologist at the Reproductive Medicine Institute in Chicago, and the chief medical officer and co-founder of fertility platform Carrot Fertility, says she is seeing an increase in infertile men as a consequence of unnecessary testosterone therapy. “It’s not like it’s a random occurrence, it happens very frequently,” she said.
Another side effect, gynecomastia, or enlarged breasts, can subside with time or medications, but in some cases surgery is required.
In forums about testosterone, men also complain of anxiety and insomnia, irritability, hypertension, and acne, and even mention being scared of getting off T for fear of a rebound. Indeed, when the body gets used to unnaturally high levels of testosterone, said Irwig, “when they try to come off, they can have a lot of symptoms … and then they go back on the substances and it’s kind of a vicious cycle.”
Still, while some patients would prefer to get care from their own physicians, they feel they have little choice. “If this kind of treatment was available through my regular doctor, I would change clinics in a second, because it would make me feel safer,” said Luca Candela, 47, who said he only receives “perfunctory” control visits from his clinic. “But I can’t, and the improvement of my quality of life has been so substantial that I don’t want to stop.”
Physicians such as Mulhall, the Memorial Sloan Kettering urologist, have a similar view. “There is a population that could benefit from testosterone treatment and it’s still not encouraged to do it,” he said. “I would say that number is far larger than the men who are inappropriately on testosterone.”
Morgentaler agrees. “My concern is that there are a lot of men who are getting [testosterone] who don’t need it, but tragically, there’s more of the men who actually need it [who] aren’t getting treated at all.”
STAT’s coverage of health challenges facing men and boys is supported by Rise Together, a donor advised fund sponsored and administered by National Philanthropic Trust and established by Richard Reeves, founding president of the American Institute for Boys and Men; and by the Boston Foundation. Our financial supporters are not involved in any decisions about our journalism.
