A hypodermic needle (from Greek ὑπο- (hypo- = under), and δέρμα (derma = skin)) is a very thin, hollow tube with one sharp tip.

A hypodermic needle is used for rapid delivery of liquids, or when the injected substance cannot be ingested, either because it would not be absorbed (as with insulin), or because it would harm the liver.

[2][3][4][5] The ancient Greeks and Romans knew injection as a method of medicinal delivery from observations of snakebites and poisoned weapons.

[6] There are also references to "anointing" and "inunction" in the Old Testament as well as the works of Homer, but injection as a legitimate medical tool was not truly explored until the 17th century.

[7] These experiments consisted of using animal bladders (as the syringe) and goose quills (as the needle) to administer drugs such as opium intravenously to dogs.

"[9] Irish physician Francis Rynd is generally credited with the first successful injection in 1844, in the Meath Hospital in Dublin, Ireland.

[10][11] Alexander Wood's main contribution was the all-glass syringe in 1851, which allowed the user to estimate dosage based on the levels of liquid observed through the glass.

[8] Simultaneous to Wood's work in Edinburgh, Charles Pravaz of Lyon also experimented with sub-dermal injections in sheep using a syringe of his own design.

[citation needed] Charles Hunter, a London surgeon, is credited with the coining of the term "hypodermic" to describe subcutaneous injection in 1858.

[7][8] Hunter and Wood were involved in a lengthy dispute over not only the origin of the modern hypodermic needle, but also because of their disagreement as to the medicine's effect once administered.

Hypodermic needles remain essential to large volume administration or exchange in settings of trauma or dialysis.

[14] The onset of World War II spurred the early development of partially disposable syringes for the administration of morphine and penicillin on the battlefield.

Disposable needles are embedded in a plastic or aluminium hub that attaches to the syringe barrel by means of a press-fit or twist-on fitting.

The male and female luer lock and hub—produced by pharmaceutical equipment manufacturers—are two of the most critical parts of disposable hypodermic needles.