What is a subcutaneous injection?

Subcutaneous injection places testosterone into the adipose (fatty) tissue directly beneath the skin, rather than into muscle. The needle typically measures 25 to 31 gauge-thinner and shorter than those used for intramuscular delivery-and penetrates only about one-quarter to one-half inch deep. This shallower placement allows the hormone to absorb slowly and steadily into the bloodstream through the rich network of small blood vessels in subcutaneous fat.

For testosterone replacement, subcutaneous delivery offers practical differences from intramuscular injection. Patients often experience less injection site soreness because the needle enters thinner tissue and avoids muscle trauma. Absorption tends to be more gradual and consistent, which can mean more stable hormone levels between doses. Common injection sites include the abdomen (belly fat), outer thigh, and back of the arm-areas where patients can easily access fatty tissue and rotate to prevent bruising or lumps.

The method works well for patients on weekly or twice-weekly schedules and suits those who prefer smaller needles or have concerns about muscle injection. Some providers specializing in testosterone replacement therapy offer subcutaneous protocols as an alternative to traditional intramuscular shots, though absorption rates and dosing may differ slightly depending on individual body composition and injection depth.