What testosterone replacement therapy is
The testicles make testosterone under signals from the pituitary gland. When either part of that system falters, testosterone falls, a condition called hypogonadism. Primary hypogonadism starts in the testicles; secondary hypogonadism starts in the pituitary or hypothalamus. Testosterone replacement therapy gives back the hormone the body is not making, and the Endocrine Society suggests aiming for blood levels in the mid-normal range.
TRT is one branch of hormone replacement therapy. For how estrogen and progesterone are used around menopause, and how the two compare, see What is hormone replacement therapy?
Symptoms of low testosterone
- Low sex drive, erectile problems, or fewer morning erections
- Fatigue and low energy
- Loss of muscle and strength, or more body fat
- Low mood, irritability, or poor concentration
- Loss of bone density
These symptoms overlap with poor sleep, depression, thyroid problems, weight gain, alcohol, and many medications. That overlap is why symptoms alone are never enough to start treatment.
How low testosterone is diagnosed
The Endocrine Society's guideline sets out a careful sequence:
- Symptoms or signs consistent with testosterone deficiency.
- Two early-morning, fasting total testosterone tests on separate days. Levels are highest in the morning and vary from day to day, and the guideline found that at least two measurements were needed to diagnose deficiency with confidence.
- LH and FSH to tell primary from secondary hypogonadism, which changes both the workup and the treatment options, especially for fertility.
- Baseline safety labs, including hematocrit, and an assessment of prostate cancer risk in men 55 to 69 who choose prostate monitoring.
Laboratory reference ranges differ. For context, the TRAVERSE trial enrolled men with two fasting testosterone levels below 300 ng/dL plus symptoms. The guideline recommends against routine screening of the general population.
Who should not start testosterone
The Endocrine Society recommends against testosterone in men with:
- Plans to father a child in the near term
- Breast or prostate cancer, a prostate nodule, or a PSA above 4 ng/mL (above 3 ng/mL in men at high risk) without urologic evaluation
- An elevated hematocrit
- Untreated severe obstructive sleep apnea
- Severe urinary symptoms from an enlarged prostate
- Uncontrolled heart failure
- A heart attack or stroke in the past six months
- A clotting disorder (thrombophilia)
Treatment options
| Form | Advantages | Drawbacks |
|---|---|---|
| Injections (cypionate or enanthate) | Relatively inexpensive when self-injected; flexible dosing | Peaks and valleys in levels that can cause swings in mood or libido; injection-site pain |
| Gels and solutions | Daily application; flexible dosing; easy to use | Skin irritation or odor; can transfer to a partner or child through skin contact |
| Patches | Daily, steady delivery | Frequent skin reactions where the patch sits |
| Pellets | Placed under the skin and replaced infrequently | Needs a small incision each time; pellets can work their way out or become infected |
| Other forms | Long-acting undecanoate injections, buccal tablets, nasal gel | Vary by product in schedule, cost, and side effects |
The guideline lets clinicians start with any approved form, chosen by preference, how the drug behaves in the body, treatment burden, and cost. It does not recommend oral methyltestosterone. The best form is usually the one a man will use consistently and that keeps his levels steady on follow-up labs.
Monitoring on TRT
Testosterone therapy needs follow-up. The Endocrine Society's monitoring plan includes:
- Testosterone level 3 to 6 months after starting, aiming for the mid-normal range. With cypionate or enanthate injections it is checked midway between doses, and the dose or interval is adjusted if the level is above 600 ng/dL or below 350 ng/dL. Gels are checked 2 to 8 hours after application; pellets at the end of the dosing interval.
- Hematocrit at baseline, at 3 to 6 months, and then yearly. If it rises above 54%, therapy is stopped until it returns to a safe level, the man is evaluated for sleep apnea and low oxygen, and treatment restarts at a lower dose.
- PSA and prostate exam 3 to 12 months after starting in men who choose prostate monitoring, then routine screening. A confirmed PSA rise of more than 1.4 ng/mL in the first year, a confirmed PSA above 4 ng/mL, or an abnormal exam calls for a urology referral.
- Bone density after 1 to 2 years in men with osteoporosis.
- Symptoms and side effects at each visit, then a yearly review once stable.
Does testosterone therapy cause prostate cancer?
Current trial evidence does not show that it does in men who are screened and monitored. In the TRAVERSE prostate safety study, 5,204 men aged 45 to 80 with hypogonadism were randomized to testosterone gel or placebo and followed for an average of 33 months. High-grade prostate cancer occurred in 0.19% of men on testosterone and 0.12% on placebo, and any prostate cancer in 0.46% and 0.42%. Neither difference was statistically significant.
Three caveats. Men at higher prostate risk were excluded, including those with a PSA above 3 ng/mL. PSA rose slightly more on testosterone. And there were too few cancers to prove the risk is identical. Testosterone can also uncover a prostate cancer that was already present and can drive the growth of metastatic prostate cancer, which is why screening comes before treatment and PSA is followed during it.
Does testosterone therapy cause infertility?
It can. Testosterone from outside the body tells the pituitary to stop signaling the testicles, and sperm production falls. The Endocrine Society recommends against testosterone for men planning fertility in the near term. Men unsure about future children may want to bank sperm first, and a semen analysis before treatment can guide that decision. In men with secondary hypogonadism, gonadotropin treatment can stimulate sperm production and restore fertility. If children are part of your plans, raise it at the first visit.
Is testosterone replacement therapy safe?
For years the main worry was the heart. TRAVERSE, the largest trial to test it, enrolled 5,246 men aged 45 to 80 with low testosterone and existing heart disease or high cardiovascular risk. A major cardiac event occurred in 7.0% of men on testosterone gel and 7.3% on placebo, meeting the trial's test for safety. The testosterone group did have more atrial fibrillation, acute kidney injury, and pulmonary embolism.
In February 2025 the FDA required class-wide label changes for testosterone products: the TRAVERSE results were added, the cardiovascular language was removed from the boxed warning, a warning about increased blood pressure was added, and the limitation of use for age-related low testosterone was kept.
Other effects to know about:
- A rise in red blood cell count (erythrocytosis), which is why hematocrit is checked
- Acne, oily skin, and breast tenderness
- Reduced sperm production and fertility
- Less commonly, breast enlargement or new or worsening sleep apnea
TRT is not for performance enhancement
Testosterone treats a deficiency. In men with normal levels it is not indicated for building muscle, athletic performance, or general anti-aging. The Endocrine Society advises against routinely prescribing it to all men 65 or older, and expects a diagnosis built on both symptoms and repeated low levels before treatment.
Cost and insurance
The cost of testosterone replacement therapy depends on several things:
- The form. Generic injectable testosterone is relatively inexpensive when self-administered. Brand-name gels, long-acting injections, and pellets usually cost more, and pellets add a procedure each time.
- Labs. Diagnosis needs at least two morning tests plus other labs, and monitoring adds labs at 3 to 6 months and then yearly.
- Visits. Expect an initial evaluation and regular follow-ups, more often in the first year.
- Insurance. Many plans cover testosterone when low levels and symptoms are documented, sometimes with prior authorization. Coverage of specific forms varies, and some clinics are cash-pay only.
When comparing clinics, ask for the total yearly cost, including medication, labs, and visits, so you are comparing like with like.
Frequently asked questions
What is testosterone replacement therapy for men?
Testosterone replacement therapy (TRT) is prescription testosterone for men with symptoms of deficiency and consistently low blood testosterone. It aims to bring levels back into the mid-normal range. It is the main form of hormone replacement therapy for men.
How much does testosterone replacement therapy cost?
Cost depends on the form, whether a generic is available, how often you need labs and visits, and whether insurance pays. The Endocrine Society notes that self-injected testosterone is relatively inexpensive, while brand-name gels and newer formulations usually cost more. Ask any clinic for the full yearly cost, including labs, before you start.
Does insurance cover testosterone replacement therapy?
Many plans cover testosterone when hypogonadism is documented with symptoms and repeated low morning lab results, though rules differ by plan and may require prior authorization. Coverage for a particular form, such as pellets or a brand-name gel, varies more. Cash-pay clinics may not bill insurance at all, so check before your first visit.
Is testosterone replacement therapy safe?
For men with confirmed low testosterone who are monitored, the large TRAVERSE trial found no increase in major heart events compared with placebo. It did find more atrial fibrillation, acute kidney injury, and pulmonary embolism, and testosterone can raise red blood cell counts and blood pressure. Safety depends on choosing the right candidates and checking labs regularly.
Does testosterone replacement therapy cause prostate cancer?
Current trial evidence does not show that it does. In the TRAVERSE prostate study of more than 5,000 men followed for about three years, high-grade prostate cancer was rare and not significantly different between testosterone and placebo. Testosterone can speed the growth of prostate cancer that has spread, so men with prostate cancer or a concerning PSA should not start it without urologic evaluation.
Does testosterone replacement therapy cause infertility?
It can. Testosterone from outside the body suppresses sperm production, and the Endocrine Society recommends against it for men planning to father a child in the near term. Men who may want children later can consider sperm banking, and some men with secondary hypogonadism can use gonadotropin treatment that preserves sperm production instead.
How is low testosterone diagnosed?
Diagnosis needs both symptoms and consistently low testosterone. The Endocrine Society recommends measuring total testosterone on two separate mornings while fasting, because levels peak in the morning and vary from day to day. LH and FSH help show whether the problem starts in the testicles or the pituitary.
Can men with normal testosterone take TRT?
Testosterone is not indicated for men with normal levels, including for muscle building or athletic performance. The Endocrine Society also advises against routinely prescribing it to all men 65 or older, and FDA labeling keeps a limitation of use for age-related low testosterone.
Testosterone therapy in Miami
I evaluate and treat low testosterone in Miami. Every plan starts with your symptoms and two morning lab tests, and I recheck testosterone, hematocrit, and PSA where appropriate so treatment stays safe and effective. For the bigger picture, including menopause hormone therapy, read What is hormone replacement therapy?, see how I approach hormone replacement therapy in Miami, or book a consultation.
Sources
- Endocrine Society: Testosterone Therapy in Men with Hypogonadism (Clinical Practice Guideline, 2018)
- Lincoff AM, et al. Cardiovascular Safety of Testosterone-Replacement Therapy (TRAVERSE). New England Journal of Medicine, 2023
- Bhasin S, et al. Prostate Safety Events During Testosterone Replacement Therapy in Men With Hypogonadism. JAMA Network Open, 2023
- U.S. Food and Drug Administration: FDA Issues Class-Wide Labeling Changes for Testosterone Products (2025)
- ClinicalTrials.gov: TRAVERSE trial (NCT03518034)