Use an 18- to 23-Gauge Needle for Thick Injectables Like Testosterone
Selecting the right needles and syringes can be confusing.
Use these rules of thumb to help you pick the right one.
NEEDLE LENGTH depends on the injection location. In general, dispense 1/2" to 5/8" needles for many subcutaneous injections. These are short enough that they don't go too deep...and accidentally hit muscle.