Why did oral testosterone get a bad reputation?
Oral testosterone got its reputation from older tablets that had to be chemically altered to survive the liver. Plain testosterone swallowed as a pill is largely destroyed on its first pass through the liver, a problem described in a study of oral testosterone undecanoate as extensive first-pass metabolism.
The early workaround was methyltestosterone, which carries an extra chemical group at the 17-alpha position so it resists breakdown. That change came at a cost. As the Kyzatrex label summarizes, prolonged high-dose use of 17-alpha-alkyl androgens such as methyltestosterone has been associated with serious liver effects: peliosis hepatis, which the label calls potentially life-threatening, plus liver tumors, cholestatic hepatitis and jaundice.
How is Kyzatrex different?
Kyzatrex avoids that problem by using a different route rather than a different molecule. It is testosterone undecanoate, testosterone attached to a long fatty chain, taken as a capsule with food. That fatty ester is absorbed into the lymphatic vessels of the gut instead of going straight to the liver.
In that absorption study, done in dogs, lymphatic transport accounted for 91.5% to 99.7% of the testosterone undecanoate that reached the bloodstream, which is how it largely bypasses the liver’s first pass. The Kyzatrex label states plainly that it is not a 17-alpha-alkyl androgen and is not known to cause liver adverse effects.
| Feature | Methyltestosterone tablets | Kyzatrex capsules |
|---|---|---|
| Chemistry | 17-alpha-alkylated | Testosterone undecanoate, not alkylated |
| How it avoids the liver | Resists breakdown chemically | Absorbed largely through lymphatics |
| Liver warnings on label | Serious liver effects with prolonged use | Not known to cause liver adverse effects |
| Main safety focus | Liver | Blood pressure |
What blood pressure checks does the label require?
The Kyzatrex label asks for periodic blood pressure monitoring, especially in men who already have hypertension, and says it is not recommended for men whose hypertension is uncontrolled. In its 24-hour monitoring study, average blood pressure rose by 1.7/0.6 mm Hg after four months and 1.8/0.6 mm Hg after six. In men already taking blood pressure medicine, the four-month rise was 3.4/0.7 mm Hg.
Those are averages, and some men rise more. Blood pressure is now a concern across the whole testosterone class: in 2025 the FDA required a blood pressure warning on testosterone products that lacked one. The Kyzatrex label notes that its earlier boxed warning on blood pressure was removed in July 2025, but the monitoring advice remains. Our pages on whether TRT can raise blood pressure and on TRT for men on blood pressure medicines explain how that is handled.
Are there other checks on oral testosterone?
Yes, the same core labs as any TRT plus a few specific to Kyzatrex. The label sets the testosterone check 3 to 5 hours after the morning dose, at least 7 days after starting or changing the dose, and asks for periodic lipid monitoring. MedlinePlus covers the practical side for patients: take it with food twice a day, at around the same times each day. Hematocrit and PSA are monitored as with any form of testosterone. Our page on ALT and AST liver enzymes explains what those routine liver numbers mean.
How Ultimate Male uses Kyzatrex
Kyzatrex is the oral option on the Ultimate Male TRT menu, a daily capsule taken with food for men who would rather not inject. Before it is recommended, your provider reviews your blood pressure history and baseline labs, drawn on site at San Gabriel or Downey.
On treatment, blood pressure is checked at visits and testosterone is drawn at the timing the label specifies. Read more about Kyzatrex oral testosterone, see how it compares in Kyzatrex versus testosterone injections, or ask about testosterone therapy on the free 10-minute call.
