Subcutaneous injection

Subcutaneous — often shortened to “subQ” or “SC” — means under the skin. A subcutaneous injection uses a short, fine needle to place a small amount of liquid into the fatty layer that sits between your skin and your muscle. It’s the same layer people pinch on the belly or the back of the arm.

Because that fat layer has a modest blood supply, the compound seeps into the bloodstream gradually rather than all at once. Picture a slow-release rather than a splash — a steady trickle over hours. For a lot of peptides that’s exactly what you want, since a smooth level tends to beat a sharp spike.

This is the default route for most research peptides and for GLP-1 drugs like semaglutide, along with everyday medicines such as insulin. The needle is short (the fat layer is shallow), the angle is often 45 to 90 degrees, and common sites are the abdomen, upper thigh, and back of the upper arm.

For a concrete example, semaglutide is available in prefilled Ozempic pens and syringes labeled for subcutaneous use, meaning the medicine is deposited in the fat layer rather than the muscle beneath it. The official instructions name the abdomen, thigh, and upper arm as injection sites, tell patients to rotate sites, and direct users of the prefilled syringe to hold it at a 45-degree angle. In other words, “subcutaneous semaglutide” describes where the dose enters the body; it does not describe the drug’s GLP-1 receptor activity or what the compound does afterward. That distinction matters when comparing it with an intramuscular injection, where the target tissue and usual absorption pattern differ even if the substance in the syringe stays the same.

The main contrast to know is intramuscular injection, which goes deeper into the muscle and absorbs faster. Subcutaneous trades speed for a gentler, longer, and generally easier-to-give shot.