Subcutaneous injections are delivered into which tissue layer?

• A. Inject into the muscle
• B. Into the subcutaneous fat, below dermis/above muscle
• C. Into the bone
• D. Within the epidermis

Answer: (A)

Subcutaneous injections are delivered into the subcutaneous tissue, the fatty layer just beneath the skin’s dermis and above the underlying muscle. This layer is rich in fat and has a relatively slower blood supply than muscle, so medications absorbed here enter the bloodstream more gradually. That slower absorption is why many drugs given SC—like certain anticoagulants or insulin—are formulated for subcutaneous use. In contrast, injecting into the epidermis would be intradermal, into the muscle would be intramuscular, and into bone would be intraosseous, so those options aren’t correct for subcutaneous administration.