Definition: An auto-injector is a single-use device with a hidden needle that gives one fixed dose. You press it against the skin and it inserts the needle and pushes the medicine in for you. The Mounjaro single-dose pen and the Xyosted testosterone autoinjector are examples. The whole device goes into a sharps container afterwards.
How labels describe using one
The Mounjaro single-dose pen instructions say to place the clear base flat on the skin, unlock the pen, then press and hold the button for up to 10 seconds. The first click means the injection started and the second means it is done; the gray plunger then shows.
In the Wegovy pen, the needle is hidden under a needle cover. Its instructions say the injection starts when the cover is pressed firmly against the skin, and not to lift the pen until the yellow bar stops moving. The cover locks when the pen is removed, and you cannot stop and restart an injection.
Xyosted is a 0.5 mL single-dose autoinjector of testosterone enanthate for subcutaneous use in the abdomen. Its label says to discard it after use and not to reuse it.
Auto-injector vs multi-dose pen
- Dose. An auto-injector gives one set dose. A multi-dose pen holds several.
- Needle. An auto-injector has its own hidden needle. A multi-dose pen takes a new pen needle each time.
- Priming. The Mounjaro single-dose pen instructions have no priming step. The Mounjaro KwikPen instructions say to prime before each weekly injection.
- Disposal. The Mounjaro and Wegovy instructions say to put the used pen in an FDA-cleared sharps container right away, not the household trash.
Read more on Dose Track: Wegovy guide · Mounjaro guide · Testosterone enanthate guide
General education drawn from labels and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your product are the final word.
How do I know an auto-injector finished?+
It depends on the device. The Mounjaro single-dose pen gives a second click and shows a gray plunger. The Wegovy pen instructions say to wait until the yellow bar stops moving.
Can an auto-injector be reused?+
No. They are single-dose devices. The Xyosted label says to discard it after use and not reuse it.
Where does a used auto-injector go?+
Into an FDA-cleared sharps disposal container right away, according to the Mounjaro and Wegovy instructions, not the household trash.