Testosterone Replacement Therapy (TRT): Complete Guide

Who Qualifies for TRT: Clinical Criteria

TRT is indicated for men with symptomatic hypogonadism — the combination of low testosterone on lab testing plus clinical symptoms consistent with testosterone deficiency. Either criterion alone is typically insufficient.

Testosterone threshold by organization:

Guidelines vary, but most clinicians use 300 ng/dL as a practical threshold. Diagnosis requires at least two morning testosterone measurements (before 10 AM, when levels peak) using a reliable assay. Single measurements are insufficient due to diurnal variation and day-to-day fluctuation.

In borderline cases — total testosterone of 300-400 ng/dL with symptoms — clinicians check free testosterone and SHBG. High SHBG can suppress bioavailable testosterone even when total testosterone reads normal. Testosterone declines with age (~1-2% per year after 30), so context matters.

Symptoms required for diagnosis include some combination of: reduced libido, fatigue and low energy, decreased muscle mass and strength, increased body fat (especially visceral), depressed mood or low motivation, erectile dysfunction, reduced bone density, and poor concentration. See our detailed low testosterone symptoms hub and causes of low testosterone for more.

Contraindications: TRT should not be initiated in men with prostate cancer, breast cancer, untreated sleep apnea, hematocrit >50%, severe congestive heart failure, active desire for fertility, or PSA >4.0 ng/mL without urological evaluation. Men planning to father children in the near future should consider alternative approaches, as TRT suppresses sperm production.

Before starting TRT, your doctor should evaluate: PSA, hematocrit/CBC, metabolic panel, LH and FSH (to distinguish primary from secondary hypogonadism), lipid panel, and cardiovascular risk. Lifestyle interventions — weight loss, sleep optimization, resistance training — should be attempted first in functional hypogonadism, as these can increase testosterone by 100-200 ng/dL in some men. See our guide on how to increase testosterone naturally.

Types of TRT: Injections, Gels, Pellets, and Patches Compared

There is no single best delivery method for TRT — the right choice depends on your lifestyle, cost tolerance, preference for convenience vs. control, and how your body responds. Here is a clinical comparison of all major options:

Testosterone Cypionate vs. Enanthate: These are the two most commonly prescribed injectable forms in the US and are functionally interchangeable. Cypionate has a half-life of approximately 8 days and is more widely available domestically. Enanthate has a half-life of 5-7 days and is the standard in Europe. Neither is clinically superior — selection depends on availability, cost, and provider familiarity. Both are available as generics for $30-$120/month without insurance.

TRT Cost Breakdown (2025-2026)

The total cost of TRT includes medication, lab monitoring, and provider fees. Here is a realistic breakdown:

With insurance: Medicare and most commercial insurance cover FDA-approved testosterone formulations when hypogonadism is properly diagnosed and documented. Copays for injections typically run $10-$40/month; for gels, $50-$150. Prior authorization is sometimes required.

Without insurance: Generic injectable testosterone is the most affordable option — roughly $30-$120/month for medication alone. Discount programs (GoodRx) can further reduce costs. Telemedicine TRT clinics offer all-in programs starting around $100-$200/month including medication, labs, and provider access.

Total annual cost estimates:

• Injections (low end, insurance or generic): $500-$1,500/year
• Gels (mid-range, with insurance): $2,000-$4,000/year
• Concierge/telemedicine clinic: $1,500-$3,500/year all-inclusive
• Pellets: $2,000-$6,000/year

TRT Benefits: What the Evidence Shows

When TRT is appropriately prescribed for genuinely hypogonadal men, the clinical evidence supports the following benefits:

• Sexual function: Improved libido and erectile function — the most consistently demonstrated benefit. A meta-analysis of 39 RCTs found significant improvement in sexual desire, frequency of sexual activity, and erectile function.
• Body composition: Reduction in fat mass (particularly visceral fat) and increase in lean muscle mass. Average increase in lean mass: 1.6-2.0 kg over 6-12 months in hypogonadal men.
• Bone density: TRT increases bone mineral density in men with hypogonadism. Particularly important for men with osteopenia or osteoporosis related to low T.
• Mood and energy: Improved mood, motivation, and energy in men with symptomatic hypogonadism. Effects are most pronounced in men with true clinical deficiency rather than low-normal levels.
• Metabolic markers: Modest improvements in insulin sensitivity and fasting glucose in hypogonadal men with metabolic syndrome.

Important caveat: benefits are most robust in men with clearly low testosterone (<200-250 ng/dL) and documented symptoms. Men with low-normal testosterone (250-350 ng/dL) may see smaller or less consistent gains. TRT is not a general anti-aging treatment for men with normal testosterone levels — the risk-benefit ratio shifts substantially.

TRT Side Effects and Risks

All forms of TRT carry a risk profile that requires informed consent and ongoing monitoring. The major categories:

Common side effects (affecting 10-30% of users):

• Testicular atrophy and suppressed fertility: Exogenous testosterone suppresses the HPG axis, reducing LH/FSH and stopping intratesticular testosterone production. Testicular size decreases in 65-70% of users. Sperm production is suppressed in 65-90%. This is reversible in most cases — sperm counts typically recover within 6-18 months of stopping. Men who want to father children should discuss hCG co-therapy or alternatives like clomiphene/enclomiphene.
• Erythrocytosis (elevated hematocrit): Testosterone stimulates red blood cell production. Hematocrit >52% increases blood viscosity and clotting risk; this affects 10-20% of TRT users. Managed by reducing dose, switching to more frequent smaller doses, or therapeutic phlebotomy.
• Acne and oily skin: Affects 25-30%, especially with injectable forms that cause higher peak levels. Twice-weekly injections (splitting the weekly dose) reduce this significantly.
• Mood changes: Mood swings, irritability, or anxiety affect 15-25%, often correlated with peak-trough hormone fluctuations from infrequent injections.

Less common but serious (1-10%):

• Elevated estradiol / gynecomastia: Testosterone aromatizes to estradiol. Elevated estrogen causes breast tissue enlargement in 10-15%. Target estradiol: 20-40 pg/mL. Aromatase inhibitors are sometimes used if estradiol exceeds 50 pg/mL.
• Sleep apnea worsening: TRT can worsen obstructive sleep apnea. Screen for OSA before and during treatment.
• Cardiovascular effects: The 2023 TRAVERSE trial (5,246 men, 33 months) found TRT was not associated with increased major adverse cardiovascular events (MACE) vs. placebo. In February 2025, the FDA removed the prior boxed warning about cardiovascular risk from testosterone labels. However, the trial did identify elevated rates of pulmonary embolism, atrial fibrillation, and acute kidney injury in the TRT group. Men with pre-existing cardiovascular disease require individualized risk assessment.
• Prostate effects: TRT does not appear to cause prostate cancer, but it can stimulate growth of existing undiagnosed cancer. PSA monitoring is essential. TRT is contraindicated in active prostate cancer.

Monitoring Requirements on TRT

Responsible TRT requires structured monitoring to catch and manage side effects early. The standard protocol:

Key thresholds to watch:

• Hematocrit: reduce dose or phlebotomize if >52% (US guideline) or >54% (European guideline)
• PSA: investigate if >4.0 ng/mL absolute or if increase >1.4 ng/mL within 12 months
• Estradiol: investigate if >50 pg/mL with symptoms
• Target testosterone: mid-normal range, approximately 400-700 ng/dL; higher levels increase side effects without additional clinical benefit

If you have not yet tested your hormone levels, start with a comprehensive hormone panel that includes total testosterone, free testosterone, SHBG, estradiol, LH, FSH, and hematocrit. Check your levels against testosterone ranges by age to understand where you stand.

How to Get Testosterone Prescribed

TRT requires a prescription in the United States and most countries — it is a controlled substance (Schedule III). Here is the standard pathway:

1. Get a baseline hormone panel. Before any appointment, it helps to have initial data. A hormone testing panel including total testosterone (morning draw), free testosterone, SHBG, LH, FSH, estradiol, and CBC gives you and your doctor a clear starting picture.
2. See the right provider. Primary care physicians, urologists, endocrinologists, and men's health clinics all prescribe TRT. Endocrinologists and urologists have the deepest hypogonadism expertise. Telemedicine TRT clinics offer convenient access but vary in rigor.
3. Confirm with two morning testosterone draws. Guidelines require at least two separate morning measurements below threshold before initiating TRT.
4. Document symptoms. Quantified symptom questionnaires (ADAM — Androgen Deficiency in Aging Males, or AMS — Aging Males Symptoms scale) support the clinical picture. Be specific about libido, energy, sleep, mood, and body composition changes.
5. Rule out reversible causes first. Your doctor should check for and address: obesity (weight loss can increase T substantially), sleep apnea, medications (opioids, corticosteroids), nutritional deficiencies (zinc, vitamin D), and chronic illness. See causes of low testosterone for a full list.
6. Discuss and choose a delivery method. Based on your lifestyle, cost tolerance, and clinical factors, you and your provider select the appropriate formulation and starting dose.

Red flags with providers: Avoid any clinic that prescribes testosterone without confirmed baseline labs, does not monitor hematocrit and PSA, or pressures you toward expensive proprietary formulations when generic injectables would work equally well.