Oral Testosterone Replacement: Kyzatrex Vs Jatenzo

Oral testosterone replacement now comes in two main FDA-approved capsules a provider can prescribe for diagnosed low testosterone: Kyzatrex and Jatenzo. Both contain the same active drug, testosterone undecanoate, taken twice a day with food. They differ in dose strengths, how much they raise blood pressure, how a man has to eat to absorb them, and how easy they are to get. This is a side-by-side look at where the two part ways, based on their FDA labels and current guidelines, so the conversation with a licensed provider starts from facts rather than ad copy.

Oral testosterone replacement restores testosterone using a swallowed capsule of testosterone undecanoate, rather than an injection, gel, or pellet. The undecanoate form is absorbed through the lymphatic system instead of the liver, which is thought to reduce the liver toxicity associated with older oral drugs. Both treat diagnosed deficiency, not aging. Neither is approved for "low T from getting older": the FDA labels carry a Limitation of Use indicating them for hypogonadism tied to a medical condition, not age-related decline (FDA, 2025). That limitation is central to whether a man is a candidate.

What is testosterone undecanoate, and why does the oral form matter?

Testosterone undecanoate is testosterone attached to a long fatty-acid chain absorbed through the gut's lymphatic system. Because the drug rides in on dietary fat and routes around the liver, it carries a lower risk of the liver toxicity associated with methyltestosterone, the older oral option that fell out of use (Swerdloff et al., 2020). That mechanism is why oral testosterone is back on the table after decades of gels and needles. It may also lower sex hormone-binding globulin (SHBG); the clinical significance is not fully established, and guidelines base diagnosis primarily on total testosterone, with free testosterone considered in selected cases such as abnormal SHBG.

How do Kyzatrex and Jatenzo work in the body?

Both raise testosterone through the same active ingredient and peak a few hours after a dose, so the underlying pharmacology is identical. Jatenzo reached the market first in 2019; Kyzatrex followed in 2022. A third oral undecanoate, Tlando, also exists, but these two are the products men most often compare. Because the drug clears faster than a long-acting injection, levels rise and fall across the day, which is why both are dosed morning and evening. The tradeoffs between oral testosterone and injections go beyond convenience and are worth weighing with a provider.

What is the dose for each one?

Both start at a high dose and titrate based on a blood test, so the starting capsule is not the long-term dose. Kyzatrex comes in 100 mg, 150 mg, and 200 mg capsules, starting at 200 mg twice daily and adjusting between 100 mg once daily and 400 mg twice daily (Kyzatrex PI, 2022). Jatenzo comes in 158 mg, 198 mg, and 237 mg capsules, starting at 237 mg twice daily and adjusting between 158 mg and 396 mg twice daily (Jatenzo PI, 2025).

Both labels require the same thing before the first capsule: confirmed low testosterone measured in the morning on at least two separate days, plus symptoms. The American Urological Association uses a total testosterone below 300 ng/dL as a reasonable cutoff (Mulhall et al., 2018), and the Endocrine Society recommends therapy only after low levels are confirmed alongside symptoms (Bhasin et al., 2018). A level alone is not a diagnosis.

One practical difference shows up at the dinner table. Jatenzo has to be taken with a fatty meal for its fat-dependent absorption to work, while Kyzatrex is taken with food but its label does not specify a fatty meal (Kyzatrex PI, 2022). For a man who does not want to plan a high-fat breakfast around a pill, that is a real quality-of-life gap.

How well does oral testosterone restore normal levels?

Oral testosterone undecanoate brings most men with diagnosed hypogonadism back into the normal range within about three months. In Kyzatrex's pivotal open-label study of 139 hypogonadal men, between 87.8% (worst-case analysis) and 96.1% (completers) reached a 24-hour average testosterone inside the normal range of 222 to 800 ng/dL by day 90 (Kyzatrex PI, 2022). Restoring a number is not the same as fixing every symptom. Symptom response varies between individuals and is not guaranteed; some men notice changes in energy and libido over the first several weeks, while others notice little change.

What side effects should men watch for?

The main shared side effect of both capsules is a rise in blood pressure, which is why both labels call for monitoring during treatment. The degree of that rise is one notable difference, though it is one factor among several a provider weighs rather than a basis for choosing on its own. In ambulatory blood pressure monitoring, Kyzatrex raised mean blood pressure by about 1.7/0.6 to 1.8/0.6 mm Hg over four to six months (Kyzatrex PI, 2022). Jatenzo's pivotal study showed a larger mean rise of about 4.9 mm Hg systolic and 2.5 mm Hg diastolic by day 139 (Jatenzo PI, 2025). These figures come from separate trials, not a head-to-head comparison.

Neither capsule carries a cardiovascular boxed warning. The FDA removed it across the testosterone class in February 2025 after the TRAVERSE trial and replaced it with a blood pressure warning (FDA, 2025). In that trial of 5,246 men with hypogonadism and cardiovascular risk, testosterone gel was noninferior to placebo on major cardiac events but showed higher rates of atrial fibrillation, acute kidney injury, and pulmonary embolism (Lincoff et al., 2023). Those data are from transdermal testosterone rather than the oral capsules, but the mixed result is why the boxed warning came off while blood pressure and clotting are still monitored.

Jatenzo lists more common gastrointestinal complaints, including diarrhea, heartburn, burping, and nausea, plus headache, swelling in the limbs, an enlarged prostate, and higher hematocrit, and was associated with more reported side effects than Kyzatrex in clinical studies. Kyzatrex may be associated with less red-blood-cell elevation than injectable testosterone, though its label still reports increased hematocrit as a potential effect to monitor and head-to-head data are limited, so this is best read as a possible difference rather than a confirmed advantage (Kyzatrex PI, 2022). Hematocrit and cardiovascular monitoring continue regardless of route.

What are the serious risks of oral testosterone?

Both drugs share the same rare but serious risks, because they share the same active ingredient: worsening of benign prostatic hyperplasia, a possible increase in the risk of blood clots through venous thromboembolism, worsening sleep apnea in men already prone to it, and reduced sperm production that can affect fertility (Kyzatrex PI, 2022). Because testosterone is a Schedule III controlled substance, both also carry a real risk of misuse, and the dose should never exceed what a provider prescribes.

Fertility deserves a straight answer rather than a reassuring one. Exogenous testosterone typically suppresses the body's own sperm production. That suppression may reverse after stopping, but recovery is variable, can take many months, and is not assured. A man who wants children should raise fertility preservation on TRT, such as a semen analysis or adjuncts like hCG, with his provider before starting.

Mood changes, including depression, are recognized considerations with testosterone therapy as a class. Jatenzo's labeling addresses this explicitly: during clinical studies, multiple patients reported new or worsening depression, mood changes, and suicidal thoughts (Jatenzo PI, 2025). Because both products share the same active ingredient, this is better understood as a class consideration than a confirmed difference, and any man with a mental health history should discuss it with his provider. Overall, the risk profiles are close, the differences are in degree, and the right call depends on the individual man's health.

Who should not take oral testosterone?

Some men are ruled out regardless of how low their levels run. Neither Kyzatrex nor Jatenzo should be used by men with known or suspected prostate cancer or breast cancer, by women who are pregnant, or by men whose low testosterone is not caused by a diagnosed medical condition (Kyzatrex PI, 2022). That last group is the age-related "low T" population the labels exclude. This is why the evaluation for hypogonadism is not a formality, and why it helps to understand the symptoms of low testosterone before assuming a capsule is the answer.

What about access and cost?

For years the real barrier to oral testosterone was not the drug, it was insurance, with some oral options positioned behind gels and injections by some payers, though coverage varies and changes over time. Cost also varies widely by coverage, dose, and how a man obtains the medication, so a flat price comparison is misleading. The more durable point is the access model: some oral testosterone is now offered through cash-pay channels that skip insurance, and telehealth hormone care has widened access. Any program that quotes a price should state plainly what is included, what is not, and the billing terms. Marek Health is direct-pay, and HSA or FSA funds may be eligible.

Kyzatrex vs Jatenzo at a glance

The two capsules are closer than their marketing suggests and farther apart than their shared ingredient implies. A man who knows his own blood pressure, fertility plans, mental health history, and how he actually eats brings most of what he needs to a conversation with a provider. The right choice is individualized and best made together with that provider through shared decision-making, weighing personal risk factors, preferences, and goals, including whether a pill is even the right route compared with a capsule versus injections.

Disclaimer: This blog post is intended for informational purposes only and should not be considered medical advice. Always consult a healthcare professional before making changes to your health routine.

FAQs

Is oral testosterone replacement as effective as injections? 

In men with diagnosed hypogonadism, oral testosterone undecanoate returned most trial participants to a normal range, with Kyzatrex's study showing 87.8% to 96.1% reaching normal 24-hour average levels by day 90. It avoids needles and the sharp peaks and troughs of injections. Symptom response still varies by individual, and all forms require lab monitoring.

What is the difference between Kyzatrex and Jatenzo? 

Both are twice-daily testosterone undecanoate capsules approved for diagnosed hypogonadism, but they differ in dose strengths, food rules, and blood pressure effect. Kyzatrex is taken with food without a specific fatty-meal requirement and showed a smaller mean blood pressure rise of about 1.7 to 1.8 mm Hg systolic. Jatenzo requires a fatty meal, showed a larger rise near 4.9 mm Hg systolic, and lists reported mood changes in studies.

Does oral testosterone replacement cause high blood pressure? 

Increased blood pressure is the main shared side effect of both oral testosterone products, which is why monitoring is required during treatment. The average increase differs between the two drugs. Neither carries a cardiovascular boxed warning anymore, since the FDA removed that class-wide in February 2025 and kept a blood pressure warning instead.

Can I take oral testosterone for age-related low T? 

No. Both Kyzatrex and Jatenzo are FDA-approved only for low testosterone caused by a diagnosed medical condition, not for decline due to aging. Their labels carry a specific Limitation of Use stating this. A provider confirms eligibility with two morning blood tests plus symptoms.

Does oral testosterone affect fertility? 

Testosterone therapy can suppress sperm production, which may reduce fertility. This effect is often reversible after stopping but is not guaranteed, and recovery can take months. Men planning to have children should discuss fertility preservation with a provider before starting.

How is low testosterone diagnosed before starting oral testosterone? 

Diagnosis requires blood testosterone measured in the morning on at least two separate days, with levels below the normal range, alongside symptoms. The American Urological Association uses a total testosterone below 300 ng/dL as a reasonable cutoff. A level by itself, without symptoms, is not enough to start therapy.

Which oral testosterone has fewer side effects? 

In clinical studies, Jatenzo was associated with more reported side effects than Kyzatrex, including more gastrointestinal complaints. Kyzatrex may also be associated with less red-blood-cell elevation than injectable testosterone, though head-to-head data are limited. The right choice still depends on an individual's health profile and is best made with a provider.

References

• FDA. Class-wide labeling changes for testosterone products. 2025

• J Clin Endocrinol Metab. 2018;103(5):1715-1744

• J Clin Endocrinol Metab. 2020;105(8):2515-2531

• J Urol. 2018;200:423

• JATENZO (testosterone undecanoate) prescribing information. 2025

• KYZATREX (testosterone undecanoate) prescribing information. 2022

• N Engl J Med. 2023;389:107-117