What is a subcutaneous injection?
A subcutaneous injection places medication into the fatty tissue layer directly under the skin, rather than into muscle tissue, and is a common administration route for testosterone in TRT.
In testosterone replacement therapy, a subcutaneous injection delivers testosterone into the hypodermis, the fat layer that sits between your skin and muscle. This differs from intramuscular (IM) injection, which penetrates deeper to place the hormone directly into muscle tissue. Subcutaneous injections use shorter, finer needles and are typically given in areas like the abdomen, thigh, or back of the arm.
The method matters for TRT patients because absorption rates and injection frequency vary between routes. Subcutaneous testosterone tends to be absorbed more gradually than intramuscular doses, often allowing for less frequent dosing schedules. Many patients on TRT choose subcutaneous administration because it can feel less intimidating than IM injection and requires minimal training to perform at home.
Testosterone formulations come in preparations designed for different injection routes, so the medication type your provider prescribes affects which method you use. Some patients rotate between both methods depending on their response and preference. If you are evaluating TRT options, a TRT provider can discuss which injection route suits your treatment goals and comfort level.