Testosterone injection needle

The Half Lives of Different Forms of Testosterone

The following table lists the half-life of the most popular forms of testosterone used in testosterone replacement therapy from longest to shortest.

Form of Testosterone Half-Life
Testosterone cypionate 8 days
Testosterone enanthate 4.5 days
Testosterone undecanoate 20 days
Testosterone propionate 2 days
Testosterone gel (transdermal) 2-4 hours
Testosterone patches (transdermal) 24 hours
Testosterone pellets (implanted subcutaneously) 3-6 months
Buccal testosterone 10-12 hours
Nasal testosterone 2 hours

How long does it take to reach peak testosterone levels with TRT?

The table below shows how long it would take for testosterone to reach peak levels in the bloodstream for each type of testosterone. After the peak, testosterone levels will gradually decline until the next administration.

Form of Testosterone Time to Reach Peak Levels
Testosterone cypionate 2-3 days
Testosterone enanthate 2-4 days
Testosterone undecanoate 7-14 days
Testosterone propionate 1-2 days
Testosterone gel (transdermal) 2-6 hours
Testosterone patches (transdermal) 24 hours
Testosterone pellets (implanted subcutaneously) 1-2 weeks
Buccal testosterone 30 minutes
Nasal testosterone 30 minutes

How often do you take testosterone for TRT?

The table below shows how frequently each form of testosterone is typically administered.

Form of Testosterone Typical Administration Frequency
Testosterone cypionate Every 7-10 days
Testosterone enanthate Every 7-10 days
Testosterone undecanoate Every 10-14 weeks
Testosterone propionate Every 2-3 days
Testosterone gel (transdermal) Daily
Testosterone patches (transdermal) Daily
Testosterone pellets (implanted subcutaneously) Every 3-6 months
Buccal testosterone Twice daily
Nasal testosterone Twice daily

I personally split up dosage of testosterone enanthate into two shots per week because it provides me with more stable testosterone levels and reduces side effects.


Why are testosterone enanthate and testosterone cypionate taken at the same frequencies when they have very different half-lives?

Testosterone enanthate has a half-life of approximately 4-5 days, while testosterone cypionate has a half-life of approximately 8 days. This means that it takes longer for testosterone cypionate to be eliminated from the body compared to testosterone enanthate. However, both forms of testosterone have a similar duration of action, which is why they are both typically administered every 7-10 days in testosterone replacement therapy.

In this context, “duration of action” refers to the length of time that a drug remains active in the body after administration. For testosterone replacement therapy, the duration of action refers to the length of time that the testosterone levels remain within the therapeutic range after a dose of testosterone is administered.

The duration of action of a drug can depend on many factors, not just the half-life of the drug. While testosterone enanthate and testosterone cypionate have different half-lives, they have a similar duration of action because they both have a similar pharmacokinetic profile.

While testosterone cypionate has a longer half-life than testosterone enanthate, the duration of action is not solely determined by the half-life. Other factors, such as the rate of absorption and metabolism, can also impact the duration of action. Additionally, the frequency of administration can be adjusted to achieve the desired duration of action.

Ultimately, the appropriate form of testosterone and the frequency of administration should be determined by a healthcare provider based on the individual’s specific needs and medical history.