The Testosterone Revolution: Why the Science Has Changed

Testosterone is Making a Comeback— And the Research Explains Why

For decades, testosterone replacement therapy (TRT) carried a reputation that caused hesitation among patients and healthcare providers alike. Many men were told that testosterone would increase their risk of heart attack, stroke, or prostate disease. Women were often told testosterone was simply a “male hormone” with little relevance to their own health.

The science has changed.

Over the past decade, some of the largest and highest-quality studies ever performed on testosterone therapy have challenged many of the beliefs that shaped medical practice for years. Today, evidence increasingly suggests that low testosterone may represent a marker of poor overall health, while appropriately prescribed testosterone therapy appears considerably safer than once believed.  

Testosterone Is More Than a Sex Hormone

Testosterone influences nearly every organ system.

Healthy testosterone concentrations help regulate:

• Energy production

• Muscle protein synthesis

• Bone density

• Body fat distribution

• Insulin sensitivity

• Red blood cell production

• Cognitive performance

• Mood and motivation

• Sexual function

• Physical performance and recovery

Women also produce testosterone—primarily from the ovaries and adrenal glands—and it contributes to libido, lean body mass, bone health, energy, and overall well-being. Although evidence for TRT in women is strongest for carefully selected postmenopausal women with hypoactive sexual desire disorder, testosterone remains an important physiologic hormone in both sexes.  

The Old Heart-Risk Narrative

Beginning around 2013–2015, several observational studies suggested testosterone therapy might increase cardiovascular risk.

These reports received tremendous media attention.

The FDA responded by requiring manufacturers to conduct a large randomized cardiovascular outcomes trial.

That study became the landmark TRAVERSE Trial.

The Study That Changed the Conversation

TRAVERSE enrolled more than 5,200 men with documented hypogonadism who either had cardiovascular disease or multiple cardiovascular risk factors.

Patients received testosterone replacement or placebo and were followed for major cardiovascular outcomes.

The primary endpoint included:

• Heart attack

• Stroke

• Cardiovascular death

The findings were striking.

Major cardiovascular events occurred at essentially identical rates between testosterone-treated patients and placebo.

Testosterone was shown to be noninferior to placebo for major adverse cardiovascular events.  

The FDA Responded

Following review of TRAVERSE, the FDA updated testosterone labeling.

The agency removed earlier boxed warning language suggesting testosterone increased major cardiovascular risk and instead incorporated the TRAVERSE findings into product labeling. The FDA also emphasized monitoring for increases in blood pressure, which has been observed across testosterone formulations.  

This represented one of the most significant regulatory shifts in testosterone therapy in years.

Low Testosterone May Be the Greater Risk

Numerous observational studies have associated low endogenous testosterone with:

• Obesity

• Type 2 diabetes

• Metabolic syndrome

• Coronary artery disease

• Increased visceral fat

• Higher inflammatory burden

• Increased all-cause mortality

Association does not prove causation, but these consistent findings suggest that testosterone deficiency often accompanies poorer metabolic and cardiovascular health rather than protecting against disease.

Testosterone Improves Important Cardiometabolic Markers

Across randomized trials and meta-analyses, appropriately prescribed TRT has been associated with improvements in many risk factors that matter to long-term health, including:

• Increased lean muscle mass

• Reduced visceral adiposity

• Improved insulin sensitivity

• Improved glycemic control in many men with diabetes or metabolic syndrome

• Improved physical function

• Increased bone density

• Improved quality of life

• Improved sexual health

• These improvements do not prove TRT prevents heart attacks or strokes, but they support the idea that restoring physiologic testosterone can improve overall metabolic health.

Testosterone Is Not a Fountain of Youth

Responsible physicians should avoid promising longevity or cardiovascular protection.

Current evidence supports something more nuanced:

For appropriately selected patients with documented testosterone deficiency, restoring testosterone to physiologic levels appears to improve symptoms and many markers of metabolic health without demonstrating an increased risk of major cardiovascular events in contemporary randomized trials.  

What About Women?

Testosterone is not exclusively a male hormone.

Women produce testosterone throughout life.

Declining testosterone may contribute to:

• Reduced libido

• Fatigue

• Reduced exercise performance

• Loss of lean muscle

• Reduced motivation

Professional societies support testosterone therapy primarily for carefully selected postmenopausal women with hypoactive sexual desire disorder. Research into broader applications—such as energy, cognition, and body composition—is ongoing, and treatment should be individualized.

The Future of Testosterone Medicine

The scientific conversation has shifted dramatically.

Rather than asking whether testosterone is inherently dangerous, researchers are increasingly asking:

• Which patients benefit most?

• What is the optimal physiologic range?

• How can therapy be individualized?

• Which monitoring strategies maximize safety?

Regulatory agencies have begun updating labeling to better reflect contemporary evidence, signaling a move away from assumptions based on older data.  

The Bottom Line

Testosterone is one of the body’s most important hormones.

When true testosterone deficiency is identified through appropriate evaluation, replacement therapy can improve energy, body composition, sexual health, bone health, mood, and quality of life.

Current high-quality evidence no longer supports the longstanding belief that appropriately prescribed TRT increases the risk of heart attack or stroke. At the same time, TRT is not risk-free: monitoring blood pressure, hematocrit, symptoms, and overall cardiovascular health remains essential.  

At Morrell Wellness, we believe hormone optimization should be individualized, evidence-based, and physician-guided. Our goal is not to create supraphysiologic hormone levels, but to restore healthy physiology while carefully monitoring safety and long-term health.

Selected References

Snyder PJ, et al. Cardiovascular Safety of Testosterone-Replacement Therapy. New England Journal of Medicine. 2023.

Hudson J, et al. Adverse cardiovascular events and mortality in men during testosterone treatment: an individual patient and aggregate data meta-analysis. The Lancet Healthy Longevity. 2022.

FDA. FDA issues class-wide labeling changes for testosterone products. 2025.  

FDA. Testosterone Information. Updated 2026.  

FDA/HHS. Requested updates to testosterone therapy product labels. 2026.