IM (Intra-Muscular) injections involve injecting medication directly into the muscle tissue. Select a well-muscled area such as the thigh, buttocks, or deltoids (shoulders) for the injection. These injections typically require longer needles to penetrate the muscle tissue effectively. SQ (Subcutaneous) injections involve injecting medication just beneath the skin, into the fatty layer. Locate a fatty area or loose skin, usually around the stomach region, for the injection. These injections typically utilize smaller needles.