Two Potential Downsides of TE and TC Injections

Unfortunately, testosterone injections do not mimic physiologic dosing. As a result, T levels can fluctuate in between injections. Fluctuations in testosterone are not ideal. These fluctuations can affect mood, emotional stability, and sexual activity.2

Following an injection of testosterone enanthate or testosterone cypionate, T levels exceed normal physiological levels for the first two to three days. They then steadily decline to levels below normal just prior to the next injection. The graphic below illustrates T levels following TE and TC injections. Shortening the interval between testosterone injections and lowering the dose can minimize this cyclical nature of highs and lows, which is why weekly injections of 75 to 100 mg are preferred to every other week injections of 150 to 200 mg.

Of note, another testosterone ester, testosterone undecanoate, has been approved that maintains T levels in normal ranges.7-9

In addition to not mimicking physiologic dosing, injectable testosterone also show a stronger impact on raising red blood cell levels than transdermal options.10-13 One of the more concerning potential side effects of TRT is an increase in red blood cells. Testosterone stimulates the production of red blood cells. In most cases the increase in red blood cells is small (2-5%) and within a safe range. However, for a considerable number of TRT users, testosterone injections produce red blood cell levels above safe levels over 50%. This increase in red blood cells causes your blood to become more viscous. Blood that is too viscous increases your risk of forming blood clots, which can subsequently lead to a heart attack and/or stroke.

Men using injectable testosterone should be vigilant in monitoring for this particular problem. A simple measure of your red blood cell count can alert your physician of this problem, which can then be treated. Lowering the injectable dosage and shortening the time between injections may potentially reduce the possibility of this side effect.