Oral testosterone shows 96% restoration rate — what TRT users need to know.

Why oral TRT matters: the delivery-method landscape

Male hypogonadism — clinically defined as serum testosterone below 300 ng/dL (10.4 nmol/L) in combination with symptoms — affects an estimated 2–4 million men in the United States, though many more have low-normal levels accompanied by symptomatic fatigue, reduced libido, impaired body composition, and mood changes. The American Urological Association (AUA) diagnostic threshold is total testosterone below 300 ng/dL on two morning measurements.

Until 2022, testosterone replacement therapy in the US required choosing among intramuscular injections (testosterone cypionate or enanthate, typically weekly to biweekly), transdermal gels applied daily, subcutaneous pellets implanted every 3–6 months, or scrotal or axillary patches. Each delivery method carries practical and clinical tradeoffs. Injections produce supraphysiologic peaks followed by troughs that some men experience as symptomatic. Gels carry transference risk to partners and children. Pellets require minor surgical procedures for insertion and removal. None of these is frictionless.

The question driving substantial clinical and patient interest for years has been simple: is there an oral testosterone option that works? The answer, since the FDA approved KYZATREX (testosterone undecanoate) on August 2, 2022, is yes. Two other oral testosterone formulations — Jatenzo (testosterone undecanoate, an earlier formulation) and Tlando (testosterone undecanoate, another formulation) — also carry FDA approval, making oral testosterone undecanoate the first legitimate prescription oral androgen option for hypogonadism in the US market. This article focuses primarily on KYZATREX, which has the broadest recent data disclosure and the highest-profile commercial rollout, but the key clinical points apply across formulations.

What KYZATREX is and how oral testosterone undecanoate works

KYZATREX delivers testosterone undecanoate (TU) — a fatty-acid ester of testosterone — in a lipid-solubilized oral capsule taken twice daily with food. The "with food" requirement is not optional: fat in the meal is required to stimulate lymphatic absorption via chylomicron incorporation, bypassing the hepatic first-pass metabolism that destroys standard oral testosterone.

This is the same pharmacokinetic strategy used by the older oral TU formulation (Andriol/Restandol, available in Europe and Canada for decades but never FDA-approved for the US market). The KYZATREX innovation is a refined lipid delivery matrix that improves the dose-response consistency, a wide flexible dose range (100 mg, 150 mg, and 200 mg twice-daily strengths), and a clinical titration protocol designed to hit the normal serum testosterone range (222–800 ng/dL) without supraphysiologic peaks.

Once absorbed via lymphatic transport, testosterone undecanoate is hydrolyzed to testosterone and undecanoic acid (a medium-chain fatty acid). The active compound is therefore identical to endogenous testosterone — the same molecule that cypionate and enanthate deliver after ester cleavage from injection. The difference is delivery route and pharmacokinetics, not molecular identity.

The twice-daily dosing produces a more stable concentration-time profile than weekly injections: the peak-to-trough ratio is substantially smaller, which many men report as a more consistent symptomatic experience without the energy and mood swings associated with injection protocols.

Oral testosterone undecanoate bypasses liver first-pass metabolism via lymphatic absorption — it requires fat in a meal to work. The active molecule delivered is identical to every other form of TRT: testosterone.

The Phase 3 efficacy data: 96%, 88%, and what the numbers mean

The efficacy figures for KYZATREX require a careful reading because two different numbers appear in different sources, and they measure different things.

The KYZATREX prescribing information and marketing state that the drug is "shown to restore testosterone levels in up to 96% of men." This figure comes from the broader clinical program. The published Phase 3 trial (Bernstein and Dhingra, SAGE Journals, 2024) — a 6-month, single-arm, open-label study in 155 hypogonadal males aged 18–65 — reports that 88% of participants in the pharmacokinetic evaluation population (n=139) achieved a mean plasma total testosterone concentration within the normal range (222–800 ng/dL) on the final assessment at Day 90.

The 96% figure reflects the upper bound from the broader dataset; the 88% from the pivotal published trial is the more conservatively interpreted number from the peer-reviewed paper. Both figures represent meaningful testosterone restoration rates — higher than typical injection and gel adherence-adjusted outcomes in real-world practice.

Additional efficacy data from the Phase 3 trial:

• Mean total testosterone increased from a baseline of approximately 211 ng/dL to a Day 90 mean of approximately 421 ng/dL — roughly double baseline, within the normal reference range
• Free testosterone (the biologically active, unbound fraction) approximately doubled from baseline
• Symptom improvement on the Aging Males' Symptoms (AMS) scale was reported across physical, psychological, and sexual subscales
• The study was not placebo-controlled — a limitation inherent to single-arm TRT trials where ethical constraints make withholding treatment difficult once hypogonadism is diagnosed

The TRAVERSE trial: what the long-term cardiovascular safety data says

The TRAVERSE (Testosterone Replacement in Adult Men with Hypogonadism) trial is the largest randomized cardiovascular safety trial of testosterone replacement therapy to date. It enrolled 5,246 men aged 45–80 with confirmed hypogonadism (testosterone 100–300 ng/dL), pre-existing cardiovascular disease or high cardiovascular risk, and randomized them to testosterone gel (1.62%) or placebo gel for a mean follow-up of approximately 33 months.

The primary endpoint was major adverse cardiac events (MACE): a composite of cardiovascular death, non-fatal myocardial infarction, and non-fatal stroke. The result: testosterone-replacement therapy was noninferior to placebo for MACE — meaning it did not increase the risk of this composite cardiac endpoint in a population with established cardiovascular risk. This was the finding that supported the FDA's removal of the cardiovascular black box warning.

However, TRAVERSE also found elevated rates in the testosterone group for:

• Atrial fibrillation: significantly higher in the testosterone group (hazard ratio approximately 1.35)
• Acute kidney injury: higher in the testosterone group
• Pulmonary embolism: higher in the testosterone group

These secondary findings mean the TRAVERSE data is reassuring for the specific question of MACE risk, while generating new monitoring signals for cardiac rhythm, renal function, and thromboembolic risk. The TRAVERSE population was men 45–80 with existing cardiovascular risk — not healthy young men or those using TRT for performance enhancement. Extrapolating TRAVERSE safety data to other demographics requires caution.

The 2026 Mendelian randomization study: higher testosterone and CAD risk

In February 2026, a research team led by scientists at the Medical Research Council (MRC) Epidemiology Unit at the University of Cambridge published a Mendelian randomization (MR) study in the Journal of Clinical Endocrinology & Metabolism (Volume 111, Issue 4) — the lead author Emily J Morbey and colleagues.

Mendelian randomization (MR) is a study design that uses genetic variants as natural experiments. Because genetic variants are assigned at conception and cannot be influenced by lifestyle or disease status, they serve as instruments to estimate causal relationships between an exposure (here, circulating testosterone levels) and an outcome (coronary artery disease, CAD). It is a stronger design than standard observational epidemiology for inferring causation, though it has its own limitations.

The finding: men with genetically predicted higher lifelong testosterone levels had approximately 17% higher risk of coronary artery disease, mediated at least partly through blood pressure elevation. The study used UK Biobank data and included survival analyses alongside the MR component.

This finding received attention because it appears to tension directly with the TRAVERSE noninferior-to-placebo finding. Understanding why the two are not contradictory requires understanding what each study actually measured.

The critical distinction: endogenous testosterone vs exogenous TRT

The MR study measures the effect of genetically higher endogenous testosterone across a lifetime — from birth, through adolescence, into adulthood. A person with a genetic predisposition to higher testosterone has had elevated T since puberty, affecting vascular development, red blood cell mass, blood pressure regulation, and every other testosterone-sensitive system for decades.

Exogenous TRT in hypogonadal men is an entirely different exposure: testosterone is being restored from a pathologically low level to the normal physiologic range, in middle-aged to older men, for a period of months to years. The accompanying editorial to the Morbey JCEM paper made exactly this point: "Mendelian randomization of endogenous testosterone is not the same thing as exogenous TRT in carefully treated hypogonadal men."

The comparison most clinically relevant to TRT decisions is not "men with genetically high testosterone vs normal testosterone" — it is "hypogonadal men treated with TRT vs hypogonadal men on placebo," which is exactly what TRAVERSE measured. And TRAVERSE found no MACE difference.

That said, the MR study's blood pressure finding is clinically actionable for TRT users. Higher testosterone raises blood pressure — this is the proposed mechanism through which the MR study's CAD signal operates. TRT does raise blood pressure in some men, including via hematocrit elevation (more red blood cells = increased blood viscosity = higher blood pressure). This is not a new finding, but the MR study provides stronger causal evidence for the mechanism.

Blood pressure: the specific signal to monitor

The practical implication of the 2026 MR study for TRT users is not "stop testosterone" — it is "monitor blood pressure." The signal runs through hypertension, which is a modifiable risk factor. Men on TRT who develop elevated blood pressure are acquiring a cardiovascular risk that can and should be managed.

Blood pressure elevation on TRT is most commonly associated with:

• Hematocrit rise: testosterone stimulates erythropoiesis (red blood cell production). Hematocrit above 54% is associated with hyperviscosity and elevated thrombotic and hypertensive risk. Hematocrit monitoring is standard TRT practice and triggers dose adjustment or therapeutic phlebotomy when elevated.
• Fluid retention: androgen receptors in the kidney affect sodium and water balance. Some men on TRT retain fluid, raising blood pressure. This effect is typically mild at physiologic doses but can be amplified in men with borderline renal function.
• Estradiol elevation: testosterone aromatizes to estradiol. Elevated estradiol in men also contributes to fluid retention and blood pressure. Estradiol monitoring is standard in comprehensive TRT management.

The KYZATREX Phase 3 trial reported hypertension as an adverse event occurring in 1.3% of participants — a low rate, but one that was the most common drug-related adverse event with a clear cardiovascular mechanism. The FDA's prescribing information for all oral testosterone formulations flags blood pressure monitoring as required.

Who is a candidate for oral TRT — and who should be cautious

FDA indication: KYZATREX is indicated for adult males with hypogonadism — a condition confirmed by two morning serum testosterone measurements below 300 ng/dL, combined with symptomatic presentation. It is not approved or indicated for age-related testosterone decline in the absence of clinical hypogonadism, athletic enhancement, or body composition optimization.

Men for whom the oral route offers specific advantages:

• Those with needle aversion or injection administration barriers
• Those who find gel application inconvenient or have transference concerns with partners or children
• Those who want a twice-daily oral dosing routine consistent with other medications
• Those on stable dietary patterns that include fat-containing meals twice daily (required for lymphatic absorption)

Men who require additional clinical consideration before oral TRT:

• Existing hypertension: blood pressure must be stable and monitored closely; the MR and TRAVERSE data both flag this interaction
• Personal or family history of atrial fibrillation: TRAVERSE found an elevated AF signal; pre-TRT cardiac rhythm assessment may be warranted
• History of thromboembolic events (DVT, pulmonary embolism): TRAVERSE found elevated pulmonary embolism rates; prothrombotic conditions require careful evaluation
• Prostate cancer or elevated PSA: testosterone is contraindicated in men with known or suspected prostate cancer; PSA monitoring is standard
• Polycythemia vera or high baseline hematocrit: testosterone will further raise hematocrit; baseline above 50% should prompt careful evaluation

Comparing delivery methods: oral vs injection vs gel vs pellet

No single TRT delivery method is objectively superior — the "best" method is the one that achieves consistent hormonal restoration with acceptable burden and monitoring for the individual patient.

A monitoring framework for TRT users

We do not write prescriptions. What follows is a monitoring framework for consideration with a prescribing clinician — not a self-management protocol.