subcut

Subcut, short for subcutaneous, refers to the layer of tissue just beneath the skin, consisting mainly of adipose tissue and connective tissue with a rich blood supply but less organized muscular structure than underlying muscle. It lies between the dermis and the fascia surrounding muscles. The term subcutaneous is used in anatomy as well as in medical practice, and the abbreviation subcut is often found in clinical notes, prescriptions, and nursing documentation.

Subcutaneous administration involves delivering medications into this tissue, where absorption into the systemic circulation occurs more slowly than with intramuscular injections, providing a gradual onset. The exact rate depends on factors such as blood flow, injection site, local fat thickness, and the drug formulation. Subcut injections are commonly used for insulin, certain anticoagulants and biologic therapies; vaccines are sometimes given subcutaneously, but many vaccines are intramuscular.

Sites commonly used for subcutaneous injections include the abdomen (avoiding a two-inch area around the navel), the outer aspects of the upper arms, the front of the thighs, and the buttocks. Rotating injection sites helps prevent lipodystrophy, a condition involving abnormal fat distribution.

Adverse effects are usually local and may include redness, swelling, or bruising; infection is rare. Improper technique or injection into scar tissue can affect absorption. Subcut is distinct from intradermal and intramuscular routes, each with different depths, absorption characteristics, and clinical uses.