Testosterone replacement therapy for men typically requires the injection of two different drugs: testosterone cypionate and human chorionic gonadotropin (HCG).
These two drugs have different viscosities. Testosterone cypionate is thick because it is mixed with grape seed oil to carry it into the body. HCG is thin like water.
Syringes with very narrow, small needles used to inject HCG won't work for the thicker testosterone cypionate.
I learned all of this through trial and error. My goal here is to pass this information along to you so you can skip the experimentation.
My clinic ships my package with the drugs and needles to inject. It took only one look at the 21 gauge needles that shipped with my prescription to know I didn't want to inject with them regularly.
For the uninitiated, the smaller the number, the larger the needle diameter. 21 gauge is wider/larger than 31 gauge.
For the testosterone cypionate, my first attempt at downsizing was syringes with 31 gauge needles intended for use by diabetics injecting insulin.
31 gauge needles work fine for injecting HCG, but they are too narrow to effectively allow the testosterone cypionate to pass through.
I decided to try 27 gauge needles as a compromise between 21 gauge and 31 gauge. While not splitting the difference evenly, I felt that 27 gauge was a good starting point.
At the time, I didn't realize that the term "Luer-Lok" compatible meant an industry standard system of threaded needles and syringes making thousands of combinations possible. This revelation led me to shop for syringes and needles independent of one another.
After shopping around, I settled on 31 gauge needles fixed on syringes with 50 units of capacity for injecting the HCG. I've been prescribed a 25 unit injection of HCG each week so this makes measuring easy.
For injecting testosterone cypionate, I've settled on a 1ml capacity syringes with a 27 gauge needles.
For drawing up the testosterone cypionate into the syringe from the vial, I'm using 18 gauge needles to make it quick.
After drawing up the dose from the vial into the syringe, I swap the 18 gauge needle for at 27 gauge needle so I'm not stabbing massive holes in my thigh.
Both the syringe and the needles are Luer-Lock compatible with threads. I can screw the needles on and off the syringe.
For injecting the HCG, I use 50 unit (1/2cc) syringes with 31 gauge needles.