What Is TRT?
Testosterone Replacement Therapy is exactly what it sounds like — replacing the testosterone your body isn't producing enough of. It's a prescribed medical treatment, not a supplement or booster. TRT brings your levels back into the normal range (typically 450-700 ng/dL), which is fundamentally different from supraphysiological dosing used in performance enhancement.
The goal isn't to give you "extra" testosterone. It's to restore what your body should be producing on its own, allowing your systems to function as they're designed to.
How Does TRT Work?
When you have clinically low testosterone, your body's systems that depend on this hormone — energy metabolism, muscle protein synthesis, fat regulation, mood, cognitive function, sexual health — are all operating at a deficit. TRT provides exogenous testosterone to bring levels back to normal, allowing these systems to function properly again.
After starting treatment, most men notice improvements in a predictable timeline: energy and mood improvements within 2-4 weeks, sexual function improvements within 3-6 weeks, body composition changes over 3-6 months, and full benefits by 9-12 months of consistent treatment.
Treatment Methods Compared
Testosterone can be delivered through several methods, each with distinct advantages. Intramuscular injections (cypionate or enanthate) are the most common, given weekly or bi-weekly, offering precise dosing and reliable absorption. Topical gels provide daily steady-state levels but carry transfer risk to others. Transdermal patches offer consistent delivery but may cause skin irritation. Subcutaneous pellets are implanted every 3-6 months for hands-off treatment. Oral formulations (like testosterone undecanoate) are newer options that avoid first-pass liver metabolism.
Important: TRT Is Ongoing Treatment
TRT is not a short-term fix. Because exogenous testosterone suppresses your body's natural production, stopping treatment means your levels will drop — often below where they started. This is a long-term medical commitment that requires ongoing monitoring.
Who Is a Candidate for TRT?
TRT is appropriate for men with documented low testosterone (below 300 ng/dL on two separate morning tests) AND bothersome symptoms that haven't responded to lifestyle interventions. It is NOT appropriate for men trying to conceive (TRT suppresses sperm production), men with untreated prostate cancer, men with severe untreated sleep apnea, or men with significantly elevated red blood cell counts.
Monitoring & Safety
Responsible TRT requires regular lab monitoring — typically every 3-6 months. Your provider should track total and free testosterone, hematocrit and hemoglobin (to watch for polycythemia), PSA (prostate health marker), estradiol (testosterone converts to estrogen), and lipid panel and metabolic markers.