Testosterone gel is testosterone in an alcohol-based gel that is rubbed into the skin once a day and absorbed into the blood over the following hours. It is used for testosterone replacement therapy (TRT); brands include AndroGel and Testim.
Also known as: AndroGel, Testim.
AndroGel 1.62% gives 20.25 mg of testosterone per pump press (1.25 g of gel), and comes in 20.25 mg and 40.5 mg packets. AndroGel 1% gives 12.5 mg per pump press and comes in 25 mg and 50 mg packets. Testim comes as 50 mg tubes (5 g of gel). Doses and application sites are not interchangeable between products.
The FDA labels approve testosterone gel for testosterone replacement in adult men with primary hypogonadism or hypogonadotropic hypogonadism. They say safety and efficacy have not been established for age-related low testosterone or for males under 18.
Labeled dosing differs by product. AndroGel 1.62% starts at 40.5 mg once daily in the morning on the shoulders and upper arms, adjusted between 20.25 mg and 81 mg based on morning testosterone measured before a dose (about days 14 and 28). AndroGel 1% starts at 50 mg once daily on the shoulders, upper arms or abdomen, with steps to 75 and 100 mg. Testim is 50 mg once daily on the shoulders or upper arms, up to 100 mg.
All three labels carry a boxed warning about secondary exposure: children have been virilized after touching unwashed or uncovered application sites. The labels say to wash hands after applying, cover the site with clothing, and wash the site before expected skin contact. In the AndroGel 1.62% study, 15 minutes of skin contact raised female partners' testosterone about 280%. Avoid showering or swimming for at least 2 hours after AndroGel 1.62% or Testim, and 5 hours after AndroGel 1%. The gel is flammable until dry.
The gel labels give no half-life for the gel itself. They say reported half-lives of testosterone in blood vary from 10 to 100 minutes, and that absorption from the skin continues through the whole 24-hour dosing interval, so levels after a gel dose fall much more slowly than that. After the last AndroGel 1.62% dose, testosterone returns to about baseline within 48 to 72 hours. The app uses 10 hours as a modeling value for the gel's curve; no label or study we found gives a half-life for the gel, so we do not list one. The labels give no single time to peak.