If you are a man considering testosterone replacement therapy, the most important thing to know is this: TRT is not a casual medication you start and stop like a course of antibiotics. It is, for most men, a lifelong commitment that will shut down your body’s natural testosterone production within months, potentially cause infertility, and require ongoing monitoring for cardiovascular and blood-related side effects. That does not mean it is the wrong choice — for men with confirmed hypogonadism, the benefits to muscle mass, bone density, and metabolic health are well documented — but it does mean the decision deserves far more deliberation than many men give it. Consider a 58-year-old man with Type 2 diabetes who has been feeling fatigued, struggling with concentration, and losing interest in activities he once enjoyed. His doctor orders two morning blood draws — the clinical standard — and both come back with testosterone levels well below the normal range.
For this man, TRT could meaningfully improve his insulin sensitivity, reduce his fasting blood sugar, and restore some physical vitality. But if that same man still hopes to have children, or has a history of atrial fibrillation, the calculus changes dramatically. The drug itself is not the whole story. What matters is whether it fits your specific medical picture. This article walks through everything men need to weigh before starting testosterone therapy: the available drug forms and how they differ, what the largest clinical trial in TRT history actually found about heart risk, the side effects your doctor may not emphasize enough, alternatives that preserve fertility, and the latest FDA regulatory changes that are reshaping access to these treatments in 2025 and 2026.
Table of Contents
- What Exactly Is Low Testosterone, and How Common Is It Among Men?
- What Testosterone Drug Options Are Available, and How Do They Compare?
- What Did the Landmark TRAVERSE Trial Reveal About Heart Risk?
- How Should Men Weigh the Benefits Against the Risks Before Starting TRT?
- Why Fertility Risks Are the Most Underemphasized Side Effect of Testosterone Drugs
- What the Latest FDA Regulatory Changes Mean for Men Considering TRT
- TRT, Brain Health, and What the Coming Years May Clarify
- Conclusion
- Frequently Asked Questions
What Exactly Is Low Testosterone, and How Common Is It Among Men?
Clinically low testosterone — known as hypogonadism — affects about 2.1 percent of men, roughly one in fifty, according to data compiled by SingleCare and the Cleveland Clinic. The condition becomes far more prevalent with age: approximately 35 percent of men in their seventies have low testosterone, per the American Urological Association. Symptoms include reduced energy, decreased libido, erectile dysfunction, difficulty sleeping, loss of muscle mass, and mood changes that can overlap significantly with depression and early cognitive decline — which is why this topic matters on a brain health site. What many men do not realize is how tightly low testosterone is linked to metabolic health. About 30 percent of overweight men have low-T, compared to only 6.4 percent of men at a normal weight.
Diabetes and obesity are among the strongest risk factors, creating a feedback loop: low testosterone worsens insulin resistance, which promotes weight gain, which further suppresses testosterone. This is worth understanding because it means that for some men, addressing weight and metabolic dysfunction may raise testosterone levels without drugs at all. For others, the hormonal deficit is primary — caused by problems with the testes or pituitary gland — and medication becomes necessary. The distinction matters because TRT treats the symptom, not the cause. A man whose testosterone is low because of untreated sleep apnea or a thyroid disorder may see little benefit from testosterone drugs while the underlying condition persists. The Mayo Clinic recommends that healthcare providers rule out thyroid issues, depression, sleep apnea, and medication side effects before attributing symptoms to low testosterone alone.
What Testosterone Drug Options Are Available, and How Do They Compare?
Testosterone replacement therapy comes in several forms, and the differences between them go beyond convenience. The most commonly prescribed form is injectable testosterone cypionate or enanthate, typically given weekly, biweekly, or monthly. Injections are inexpensive and effective but produce peaks and valleys in hormone levels that some men experience as mood swings or energy fluctuations between doses. Topical gels such as AndroGel and Testim are applied daily to the skin and provide more stable testosterone levels, though they carry a risk of transferring the hormone to partners or children through skin contact. Transdermal patches, also applied daily, offer another steady-delivery option but frequently cause skin irritation at the application site.
For men who prefer less frequent dosing, subcutaneous pellets — marketed as Testopel — are implanted under the skin every three to six months. On the oral side, Jatenzo is an FDA-approved testosterone capsule taken twice daily with food, which eliminates the need for injections or topical application entirely. However, if you are a man who wants to preserve the option of having children, one form deserves special attention: Natesto, a nasal gel applied three times daily inside the nose. Research from UT Southwestern Medical Center suggests Natesto may carry less risk of fertility loss than other TRT forms, because its rapid absorption and clearance may not suppress the pituitary signals that drive sperm production as aggressively as injections or gels. This is a critical distinction that most discussions of TRT forms overlook. No testosterone formulation is truly fertility-neutral, but Natesto appears to be the least disruptive among approved options.
What Did the Landmark TRAVERSE Trial Reveal About Heart Risk?
For years, the biggest concern hanging over testosterone therapy was cardiovascular safety. Earlier observational studies had raised alarms about increased heart attack and stroke risk, leading the FDA to mandate a black-box warning on all testosterone products. Then came the TRAVERSE trial, published in the New England Journal of Medicine in 2023 — the largest randomized controlled trial ever conducted on TRT, enrolling 5,246 men aged 45 to 80 who already had preexisting cardiovascular disease or were at high risk for it. The headline finding was reassuring: TRT was not associated with a higher rate of heart attack or stroke compared to placebo. This was significant enough that in February 2025, the FDA recommended removing the cardiovascular black-box warning from TRT labels. But the full picture is more nuanced than the headlines suggested.
The TRAVERSE trial also identified higher rates of atrial fibrillation and pulmonary embolism in men receiving testosterone. A 2025 meta-analysis went further, finding a greater than 50 percent increase in arrhythmia risk among men aged 40 and older on TRT compared to placebo — a finding that drew pointed commentary from Public Citizen in FDA panel discussions. For men with a brain health focus, this matters directly. Atrial fibrillation is one of the strongest modifiable risk factors for stroke and vascular dementia. A man who starts TRT to improve his energy and cognitive sharpness could, paradoxically, be increasing his risk of the very cerebrovascular events that damage cognition over time. This does not mean TRT is unsafe for everyone, but it does mean that men with existing heart rhythm issues or a family history of atrial fibrillation should have a frank conversation with their cardiologist, not just their urologist or endocrinologist, before starting treatment.
How Should Men Weigh the Benefits Against the Risks Before Starting TRT?
The documented benefits of TRT are real but more modest than many men expect. The therapy consistently increases muscle mass and strength and improves bone mineral density, according to the Mayo Clinic. For men with Type 2 diabetes and confirmed low testosterone, a 2021 study published in PMC found that TRT can reduce fasting blood sugar, total cholesterol, and triglycerides — meaningful metabolic improvements. The Cleveland Clinic notes that TRT can improve insulin sensitivity and reduce HbA1c in diabetic men. Where expectations often collide with reality is in the areas of energy and sexual function. The American College of Physicians found that TRT “might improve sexual function somewhat” but found little evidence that it meaningfully improves vitality or energy. That gap between marketing promises and clinical findings is worth sitting with.
Many men come to TRT hoping it will restore the drive and stamina of their thirties, and while some do experience subjective improvement, the clinical data suggests the effect on overall vitality is modest at best. On the risk side, the tradeoffs are concrete. TRT shuts down natural testosterone production and sperm production within months, potentially causing infertility and testicular atrophy. Recovery of natural production after stopping can take months to years, and some men never fully recover. The FDA now requires labels to warn about blood pressure increases, based on post-market ambulatory monitoring studies showing statistically significant elevations in men on TRT versus placebo. There is also the risk of polycythemia — an elevated red blood cell count that increases clotting risk and requires regular blood monitoring. The most common side effects of injectable forms include injection site redness, reported in about 26 percent of men, and injection site reactions in roughly 4 percent.
Why Fertility Risks Are the Most Underemphasized Side Effect of Testosterone Drugs
Among all the risks of TRT, fertility suppression is arguably the most consequential and the least discussed in initial consultations. When a man takes exogenous testosterone, his brain detects the elevated hormone levels and signals the pituitary gland to stop producing luteinizing hormone and follicle-stimulating hormone — the two hormones that drive sperm production in the testes. Within a few months, sperm counts can drop to zero. The testes themselves shrink because they are no longer being stimulated to function. This is particularly problematic for men in their thirties and forties who may not have completed their families. A man diagnosed with low-T at 38 might start injections without fully understanding that he is effectively choosing a form of male contraception.
While fertility can recover after stopping TRT, the timeline is unpredictable — months to years, according to clinical sources — and some men require additional medical intervention to restore sperm production. Cleveland Clinic and UT Southwestern both flag this as a critical counseling point. For men who want to treat low testosterone symptoms while preserving fertility, alternatives exist. Clomiphene citrate, a selective estrogen receptor modulator originally developed for female infertility, is emerging as the most promising non-testosterone alternative. Rather than replacing testosterone from outside the body, clomiphene stimulates the brain’s own signaling pathways to increase testosterone production naturally, without suppressing sperm output. It is used off-label for this purpose, and while it does not produce testosterone levels as high as direct replacement, it offers a meaningful option for men who are not ready to close the door on fatherhood. Nasal testosterone with Natesto, as mentioned earlier, is another option worth discussing with a fertility-aware urologist.
What the Latest FDA Regulatory Changes Mean for Men Considering TRT
The regulatory landscape around testosterone therapy shifted significantly in 2025 and into 2026. After the TRAVERSE trial data showed no increase in heart attack or stroke risk, the FDA in February 2025 recommended removing the longstanding cardiovascular black-box warning — a move that effectively lowered the perceived risk profile of these drugs. At the same time, the agency added new label requirements warning about blood pressure increases, based on post-market ambulatory blood pressure studies that showed statistically significant elevations in men on TRT versus placebo.
Then in December 2025, an FDA Expert Panel on testosterone replacement therapy went further, urging the agency to loosen restrictions and expand access to TRT. The panel cited accumulating evidence that testosterone therapy does not raise heart attack, stroke, or prostate cancer risk in appropriately selected men — a conclusion reported by NBC News and documented in Federal Register filing 2025-22466. For men who have struggled to get insurance coverage or prescriptions for TRT, these regulatory changes may eventually translate into easier access. But easier access also means more men may start treatment without the thorough workup the therapy demands — two confirmed morning blood tests, exclusion of other causes, and a clear discussion of the lifelong nature of the commitment.
TRT, Brain Health, and What the Coming Years May Clarify
The relationship between testosterone and cognitive health remains one of the most intriguing open questions in men’s brain aging research. Low testosterone has been associated in observational studies with increased risk of cognitive decline and Alzheimer’s disease, but whether TRT can prevent or slow that decline has not been established in large randomized trials. The TRAVERSE trial was not designed to answer cognitive questions, and the existing evidence is too preliminary to recommend TRT as a brain-protective strategy.
What is clearer is that the metabolic benefits of TRT in appropriate candidates — improved insulin sensitivity, reduced blood sugar, better lipid profiles — align with known protective factors against vascular dementia and age-related cognitive decline. As the FDA loosens access restrictions and more men receive treatment, longer-term data on cognitive outcomes should emerge. For now, the honest answer is that TRT may indirectly support brain health through metabolic improvement, but anyone framing it as a cognitive enhancement drug is getting ahead of the science.
Conclusion
Testosterone replacement therapy is a legitimate and effective treatment for men with confirmed hypogonadism, offering meaningful improvements in muscle mass, bone density, and metabolic markers — particularly for men with Type 2 diabetes and obesity. The TRAVERSE trial put to rest the most acute cardiovascular fears, and recent FDA actions have begun removing regulatory barriers that limited access. But the therapy is not without serious tradeoffs: fertility suppression, testicular atrophy, increased arrhythmia risk, blood pressure elevation, and the reality that stopping treatment may not restore natural hormone production for months or years, if ever.
Before starting any testosterone drug, men should insist on at least two morning blood tests to confirm low levels, a thorough evaluation for other causes of their symptoms, and an honest conversation with their provider about fertility goals, heart rhythm history, and long-term monitoring requirements. For men who want to preserve fertility, clomiphene citrate and nasal testosterone offer alternatives worth exploring. TRT can be the right choice — but only when it is a fully informed one.
Frequently Asked Questions
How is low testosterone officially diagnosed?
Diagnosis requires at least two blood tests drawn in the morning, when testosterone levels peak, both showing levels below the normal range. The Cleveland Clinic and Urology Care Foundation both consider this the standard of care before any treatment begins.
Will TRT make me infertile?
TRT suppresses sperm production, often to zero, within a few months of starting treatment. This effect is usually reversible after stopping, but recovery can take months to years, and full recovery is not guaranteed. Men who want children should discuss alternatives like clomiphene citrate or Natesto nasal gel with their doctor before starting standard TRT.
Does testosterone therapy increase heart attack risk?
The TRAVERSE trial — the largest randomized controlled trial on TRT, with 5,246 men — found no increase in heart attack or stroke risk compared to placebo. However, the trial did find higher rates of atrial fibrillation and pulmonary embolism, and a 2025 meta-analysis identified a greater than 50 percent increase in arrhythmia risk in men on TRT.
What is the most common form of testosterone replacement therapy?
Injectable testosterone cypionate or enanthate is the most commonly prescribed form, typically given weekly or biweekly. Other options include daily topical gels, transdermal patches, subcutaneous pellets implanted every three to six months, nasal gel applied three times daily, and oral capsules taken twice daily with food.
Can I stop TRT once I start?
You can stop, but recovery of natural testosterone production is slow and uncertain. Because TRT shuts down your body’s own hormone production, it can take months to years for the testes to resume normal function after discontinuation. Some men require additional medical treatment to restart natural production, and a small number may not fully recover.
Are there alternatives to TRT that do not cause infertility?
Clomiphene citrate, a selective estrogen receptor modulator used off-label, stimulates the body’s own testosterone production without suppressing sperm output. Natesto, a nasal testosterone gel, may also carry less fertility risk than other TRT forms, according to research from UT Southwestern Medical Center.
