Hypodermic

Hypodermic is an adjective relating to structures or actions beneath the skin. In medicine, it most often refers to methods and instruments used to inject substances into or withdraw fluids from subcutaneous tissue, especially the hypodermic needle and syringe themselves.

A hypodermic needle is a slender, hollow steel tube sharpened to a bevelled tip. When attached to a syringe, it enables delivery of liquids by injection or withdrawal of body fluids by suction. Injections are categorized by depth: intradermal, subcutaneous, and intramuscular.

The hypodermic syringe emerged in the 1850s through independent efforts in France and Britain. Charles Gabriel Pravaz in France and Alexander Wood in the United Kingdom developed functional devices that combined a metal syringe with a sharpened needle, enabling direct administration of drugs such as morphine. The invention facilitated rapid, controlled delivery of medications and later supported vaccines and anesthesia.

Medical uses include vaccines, local anesthesia, analgesia, and the delivery of insulin and other medications. The technique is also used to withdraw blood or other fluids for laboratory testing. The term hypodermic remains in use to describe both the instrument and the injection technique.

Modern practice relies on sterile, disposable syringes and needles to reduce infection and cross-contamination. Safety measures address needle-stick injuries; disposal is handled with sharps containers and appropriate handling practices. Needle gauges vary by application, with finer gauges used for subcutaneous or intradermal injections and thicker gauges for some intramuscular injections.