TRT Side Effects: What to Expect and How to Manage Them, Backed by 4 Studies (2026)

The TRAVERSE trial — 5,246 men with hypogonadism and elevated cardiovascular risk — found no increased rate of major adverse cardiac events on TRT compared to placebo over a median 33-month follow-up (Lincoff et al., NEJM 2023). For most men with documented hypogonadism, TRT side effects are manageable, predictable, and preventable with proper medical supervision. But some providers and online clinics minimize these risks, leaving patients unprepared when side effects do occur. Here is what to actually expect.

Key Takeaways

• TRAVERSE found no increased cardiovascular risk from TRT in 5,246 high-risk men over 33 months (Lincoff et al., NEJM 2023)
• Most common short-term side effects: acne, mild fluid retention, mood fluctuations during dose adjustment
• Hematocrit elevation is the most-monitored side effect; addressed via dose adjustment or therapeutic phlebotomy
• Testicular atrophy occurs in nearly all men on TRT (~20–30% volume reduction); reversible after stopping
• Elevated estradiol and gynecomastia are dose-dependent and manageable
• Prostate cancer concerns have been largely debunked by modern research; baseline PSA still recommended
• Endocrine Society 2018 guidelines provide the standard monitoring framework (Bhasin et al., JCEM 2018)

Common Side Effects of TRT

The following side effects are relatively common, especially in the first few months of therapy. Most are mild, and many can be addressed with dosage adjustments or supportive treatments.

Acne and Oily Skin

Testosterone stimulates sebaceous glands, increasing oil production in the skin. This can lead to acne breakouts, particularly on the back, shoulders, and face. This side effect is more common in men who were acne-prone in their youth and tends to be most noticeable in the first three to six months of therapy as your body adjusts to higher hormone levels. For most men, acne improves over time as levels stabilize. If it persists, your provider may recommend topical treatments, dose adjustments, or more frequent but smaller injections to reduce hormonal peaks.

Fluid Retention and Bloating

Testosterone promotes sodium and water retention through its effects on the kidneys. This can cause mild bloating, puffiness in the face or extremities, and a small weight gain (typically 3 to 7 pounds of water weight in the first few weeks). It is almost always temporary and resolves as the body adapts. Staying well-hydrated and keeping sodium moderate helps. If fluid retention is significant or persistent, the dose may be too high or estradiol may need to be checked.

Mood Changes

TRT generally improves mood, reducing depression, irritability, and anxiety associated with low testosterone. But some men experience mood fluctuations during the adjustment period. This is particularly common with injectable testosterone, which creates peaks and troughs in hormone levels. Some men report feeling more emotionally reactive or having mood swings in the days following an injection. These fluctuations typically diminish as the body adjusts. They can be minimized with more frequent injections or topical formulations that produce more stable daily levels.

Testicular Atrophy

When you supplement testosterone externally, the brain detects the elevated levels and reduces signaling to the testes. Without this stimulation (via luteinizing hormone), the testes gradually shrink, typically by 20% to 30%. This is one of the most common and predictable side effects of TRT. It is not painful or harmful in itself, but it does affect fertility, since the testes also produce sperm under the same hormonal signaling.

Increased Hematocrit and Red Blood Cell Count

Testosterone stimulates erythropoiesis (the production of red blood cells). A modest increase can be beneficial, improving oxygen delivery and energy, but excessive red blood cell production thickens the blood and raises clotting risk. This is measured through hematocrit, the percentage of blood volume made up of red blood cells. Normal hematocrit for men is roughly 38% to 50%. TRT can push hematocrit above 50%, and levels above 54% are generally considered a risk threshold.

This is one of the most important reasons for regular blood monitoring during TRT. If hematocrit rises too high, your provider may reduce your dose, adjust injection frequency, or recommend therapeutic phlebotomy (blood donation) to bring levels down. This side effect is more common with injectable testosterone than with topical formulations.

Changes in Sleep Patterns

Most men report improved sleep on TRT, but some have initial trouble falling asleep or more vivid dreams. In men predisposed to sleep apnea, TRT may worsen the condition, though the evidence is mixed. Existing sleep apnea should be treated before or alongside TRT. A 2014 review in the Journal of Clinical Sleep Medicine concluded that TRT may worsen sleep apnea in some men but does not appear to cause it in men without a predisposition.

Less Common but Serious Side Effects

The following side effects are less frequent but require awareness and monitoring. This is why TRT should always be managed by a qualified provider with regular laboratory follow-up.

Polycythemia

Polycythemia is an excessive increase in red blood cell mass that goes beyond the moderate increase described above. It significantly raises the risk of blood clots, stroke, and cardiovascular events. It is the most serious hematologic risk of TRT and is the primary reason that regular complete blood count monitoring is non-negotiable during therapy. Men who smoke, live at high altitudes, or have a history of polycythemia are at increased risk. If caught early through routine blood work, polycythemia is easily managed with dose reduction or phlebotomy.

Elevated Estrogen and Gynecomastia

Testosterone is partially converted to estradiol (an estrogen) by the aromatase enzyme, particularly in fat tissue. If doses are too high or a man carries significant body fat, estradiol levels can rise enough to cause symptoms: breast tenderness, nipple sensitivity, emotional changes, or breast tissue growth (gynecomastia). Monitoring estradiol and adjusting the testosterone dose, or in some cases adding an aromatase inhibitor, can prevent or reverse this.

Cardiovascular Considerations

For years, the cardiovascular safety of TRT was debated on the basis of conflicting and often poorly designed studies. The TRAVERSE trial, published in the New England Journal of Medicine in 2023, was a randomized, double-blind, placebo-controlled study evaluating cardiovascular safety in over 5,000 men aged 45 to 80 with hypogonadism and existing cardiovascular risk factors.

TRAVERSE found that testosterone therapy did not increase major adverse cardiac events (heart attack, stroke, or cardiovascular death) compared to placebo. This was the first high-quality evidence addressing a long-standing concern. However, the trial noted a higher incidence of atrial fibrillation, pulmonary embolism, and non-fatal arrhythmias in the testosterone group, which is why ongoing monitoring matters.

Prostate Considerations

The historical concern that TRT causes prostate cancer has been largely debunked by modern research. The saturation model, proposed by Dr. Abraham Morgentaler, demonstrates that prostate tissue androgen receptors are fully saturated at relatively low testosterone levels, meaning that raising testosterone above this saturation point does not meaningfully increase prostate stimulation. Multiple studies and meta-analyses have failed to find an increased risk of prostate cancer with TRT. However, TRT is contraindicated in men with active prostate cancer, and baseline PSA testing is recommended before starting therapy.

How Proper Monitoring Prevents Problems

The most important factor in TRT safety is regular monitoring by a knowledgeable provider. Nearly every serious side effect of TRT is preventable or manageable when caught early through routine blood work. A responsible protocol includes laboratory monitoring at specific intervals.

1. Baseline labs before starting therapy: total testosterone, free testosterone, CBC, metabolic panel, lipid panel, estradiol, PSA, LH, FSH
2. Follow-up labs at 6 to 8 weeks: assess initial response, check hematocrit, estradiol, and testosterone levels
3. Labs at 3 to 6 months: confirm stable levels, recheck hematocrit and metabolic markers
4. Ongoing labs every 6 to 12 months: comprehensive panel to ensure long-term safety and efficacy

This monitoring schedule allows your provider to catch issues like rising hematocrit, elevated estradiol, or changes in prostate markers before they become clinically significant. It also allows for ongoing dose optimization to ensure you are receiving the lowest effective dose for symptom relief.

The Bottom Line: Is TRT Safe?

TRT is a well-studied medical therapy with a favorable risk-benefit profile when used appropriately in men with documented testosterone deficiency. It is not risk-free (no medical therapy is), but the risks are well-characterized, predictable, and manageable with proper supervision. The men who get into trouble with TRT are almost always those who self-prescribe, use underground sources, skip blood work, or work with providers who do not monitor adequately.

At PrimeHealth, patient safety is the foundation of our protocol. Every patient receives baseline labs, regular follow-up testing, and direct access to our medical team. We monitor hematocrit, estradiol, liver function, lipids, and prostate markers throughout treatment, and adjust quickly when needed. The goal is to optimize your testosterone safely and with full transparency about what to expect. Start your free assessment today.

Sources

• Lincoff AM, Bhasin S, Flevaris P, et al. Cardiovascular Safety of Testosterone-Replacement Therapy (TRAVERSE trial). N Engl J Med. 2023;389(2):107-117.
• Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103(5):1715-1744.
• Corona G, Giagulli VA, Maseroli E, et al. Testosterone supplementation and body composition: results from a meta-analysis study. Eur J Endocrinol. 2016;174(3):R99-116.
• American Urological Association. Evaluation and Management of Testosterone Deficiency Guideline.

Last updated: April 2026.