TRT for Beginners: Who Qualifies, What It Helps, and What It Risks

TRT is a prescription treatment for men who have both symptoms of low testosterone and blood tests that confirm it, usually under 300 ng/dL on two mornings. It is often described as good for the heart. The largest trial found it neutral for heart attacks and strokes, with more atrial fibrillation and blood clots in the lungs, and the FDA now warns that every testosterone product can raise blood pressure.

What is TRT?

Testosterone replacement therapy (TRT) gives your body testosterone from outside. FDA-approved forms include injections, gels, patches, oral products, and a buccal system applied to the upper gum or inner cheek (FDA 2025).

The goal is a normal level. The American Urological Association (AUA) recommends adjusting the dose to reach the middle third of the normal range (statement 22, Conditional, Grade C), and the Endocrine Society suggests aiming for the mid-normal range (AUA 2018; Endocrine Society 2018). For reference, the harmonized normal range in healthy young men runs from about 264 to 916 ng/dL (Endocrine Society slides, 2018).

hCG and clomiphene are sometimes listed as TRT, but neither is testosterone. The AUA says clinicians "may" use them, or aromatase inhibitors, in men with low testosterone who want to keep their fertility (statement 27, Conditional, Grade C).

Who qualifies for TRT?

Two things have to be true: you have symptoms or signs of low testosterone, and your blood tests confirm it.

The AUA uses total testosterone below 300 ng/dL as the cutoff (statement 1, Moderate, Grade B), measured on two separate early mornings (statement 2, Strong, Grade A). The Endocrine Society asks for levels that are "unequivocally and consistently low", confirmed with a repeat fasting morning test. When total testosterone sits near the lower limit, or you have a condition that changes sex hormone-binding globulin (SHBG, the protein that carries testosterone in the blood), it adds a free testosterone test (Endocrine Society 2018).

Symptoms start the evaluation, but they cannot settle it. Low sex drive, erectile problems, fatigue, and low mood all appear on lists of low-T symptoms. The AUA notes that these symptoms "are very non-specific and can be manifestations of other conditions (e.g., chronic fatigue, chronic stress, a depressed state)" (AUA 2018). If your levels come back in the normal range, the next step is looking for those other causes. Starting TRT with a level of 450 ng/dL is a separate question with its own answer.

A confirmed low level also calls for a search for the cause (Endocrine Society 2018). Opioid use and stopping anabolic steroids are two causes the guideline authors list as becoming more common (Endocrine Society slides, 2018). Excess weight is another: in a meta-analysis of 24 studies, low-calorie diets and bariatric surgery both raised total testosterone, and the rise was larger in men who lost more weight (Corona et al., 2013).

Does age matter?

The diagnostic criteria are the same at 30 as at 60. What changes is how readily a guideline backs treatment for age alone. The FDA approves testosterone "solely for use in men who lack or have low testosterone levels in conjunction with an associated medical condition", and its 2025 update kept the label's limitation of use for age-related low testosterone (FDA 2025). The Endocrine Society recommends against routinely prescribing testosterone to all men 65 or older with low levels, and suggests offering it case by case to older men with symptoms and consistently low morning levels (Endocrine Society slides, 2018).

What does TRT improve?

Sexual function has the strongest evidence. The Endocrine Society's systematic review found significant improvement in libido, erectile function, and sexual activity, and no statistically significant difference in energy or mood. It also found benefits for anemia and for bone density in the spine and hip, based on the Testosterone Trials (Endocrine Society slides, 2018).

The Testosterone Trials were placebo controlled: 790 men aged 65 or older with testosterone under 275 ng/dL used a gel or a placebo gel for one year. Testosterone brought a moderate benefit to sexual function, some benefit to mood and depressive symptoms, and no benefit to vitality or walking distance (Snyder et al., NEJM 2016). These were older men, and the trial lasted a year, so it says less about younger men or longer use.

Is TRT good or bad for your heart?

Neither claim holds up. TRT is not shown to protect the heart, and the largest trial did not find that it causes heart attacks.

TRAVERSE (NEJM 2023) randomized 5,246 men aged 45 to 80 who had heart disease or a high risk of it, symptoms of low testosterone, and two fasting levels under 300 ng/dL. Over about 33 months of follow-up, heart attack, stroke, or cardiovascular death occurred in 7.0% of men on testosterone gel and 7.3% on placebo. That result met the trial's test for noninferiority (testosterone was not worse than placebo); it was not designed to show protection. Atrial fibrillation (an irregular heart rhythm), acute kidney injury, and pulmonary embolism (a blood clot in the lungs) were more frequent with testosterone (TRAVERSE, 2023).

In 2025 the FDA removed the Boxed Warning language about cardiovascular risk from testosterone labels. In the same action it added an increased blood pressure warning to products that lacked one, after ambulatory blood pressure studies "confirmed an increase in blood pressure with use of all testosterone products, class-wide" (FDA 2025). This guide on whether TRT raises blood pressure goes into more detail.

The AUA still asks clinicians to tell patients that "it cannot be stated definitively whether testosterone therapy increases or decreases the risk of cardiovascular events" (statement 20). That statement predates TRAVERSE.

What labs come before and after starting?

Before starting:

• Two early-morning total testosterone tests (AUA statements 1 and 2).
• Hemoglobin and hematocrit (the share of your blood made of red cells), with counseling about the higher risk of polycythemia (too many red cells) (AUA statement 11, Strong, Grade A).
• PSA in men over 40, to rule out prostate cancer before treatment (AUA statement 12, Clinical Principle) (AUA 2018).

After starting, the Endocrine Society checks testosterone 3 to 6 months in, aiming for the mid-normal range, and checks hematocrit at baseline, 3 to 6 months, and then yearly (Endocrine Society slides, 2018). The AUA measures testosterone every 6 to 12 months while on therapy (statement 30, Expert Opinion). AlphaMD providers review labs before prescribing and order follow-up labs.

What are the side effects?

A rise in red blood cells is the most common one. In the Endocrine Society's review, erythrocytosis (hematocrit above 54%) was the most frequent adverse event and was significantly more common with testosterone (Endocrine Society slides, 2018). The review summary gives no single rate.

The DEPO-Testosterone (testosterone cypionate) label lists these as well (DailyMed):

• Acne, oily skin (seborrhea), and male-pattern hair loss.
• Breast enlargement (gynecomastia), which "may develop and occasionally persists".
• Increased or decreased libido, headache, anxiety, and depression.
• Higher blood pressure, which "can increase cardiovascular (CV) risk over time".
• Blood clots in the legs or lungs, from postmarketing reports.
• Lower sperm production.

TRAVERSE adds atrial fibrillation, acute kidney injury, and pulmonary embolism, all more frequent than with placebo (TRAVERSE, 2023).

Does TRT affect fertility?

It can. The testosterone cypionate label says that at large doses, testosterone can suppress sperm production by lowering the pituitary's output of follicle-stimulating hormone (FSH), and that low sperm counts may follow prolonged use or excessive doses (DailyMed).

The AUA is direct: "Exogenous testosterone therapy should not be prescribed to men who are currently trying to conceive" (statement 23, Strong, Grade A) (AUA 2018). If you want children now or soon, raise it with your prescriber before starting. This article on how TRT affects sperm production covers the options.

Who should not start TRT?

The Endocrine Society recommends against starting testosterone in men who (Endocrine Society 2018):

• Plan to father a child in the near term.
• Have breast or prostate cancer.
• Have a prostate nodule or hardness that can be felt on exam.
• Have a PSA above 4 ng/mL, or above 3 ng/mL with a higher prostate cancer risk (for example, African American men or men with a first-degree relative diagnosed with prostate cancer), without further urology evaluation.
• Have an elevated hematocrit.
• Have untreated severe obstructive sleep apnea.
• Have severe lower urinary tract symptoms.
• Have uncontrolled heart failure.
• Had a heart attack or stroke in the last 6 months.
• Have thrombophilia (an inherited or acquired tendency to form blood clots).

Common questions

Is TRT the same as taking steroids?

Testosterone is the hormone in both, so the difference lies in the dose and the monitoring. TRT doses are adjusted to reach the middle third of the normal range (AUA statement 22), with scheduled testosterone and hematocrit checks.

Can younger men get TRT?

Yes, if they meet the same criteria: symptoms plus confirmed low morning levels. A low level at any age calls for a search for the cause (Endocrine Society 2018), and opioid use and stopping anabolic steroids are two causes the guideline authors name.

Will TRT fix my energy?

Maybe not. In the Endocrine Society's review, testosterone made no statistically significant difference to energy, and the Testosterone Trials found no benefit for vitality. Sexual function is where the trials show the clearest gains.

Bottom line

TRT is for men with symptoms and testosterone confirmed low on repeat morning tests, after other causes have been looked for. It most reliably improves sex drive and erectile function. In TRAVERSE it did not raise heart attack or stroke risk, but it brought more atrial fibrillation and lung clots, and every testosterone product now carries a blood pressure warning. Men trying to conceive should not start it.

AlphaMD's testosterone replacement therapy program starts with labs reviewed by a licensed provider.