HGH pens are injection devices designed to deliver recombinant human growth hormone (r-hGH) for treating growth hormone deficiency and related conditions in children and adults. These pens are typically prefilled with liquid growth hormone (such as Norditropin or Genotropin) and allow for subcutaneous administration, usually once daily.

Modern HGH pens come in reusable or disposable forms and are engineered for ease of use, accuracy, and patient adherence. Features often include a dose dial, injection button, and dose-display window. Some advanced pens, like the prototype device studied for Saizen®, have aluminum bodies, clear cartridge windows, and injection feedback mechanisms to reassure users that the full dose was delivered. These pens are designed to be comfortable to hold and simple to operate, suitable for both children and adults, and help improve adherence to the demanding injection regimen required for effective therapy.