Definition: An insulin pen is a prefilled device that holds several doses of a liquid medicine. You attach a new pen needle, set the dose, and inject. The name comes from insulin, but several GLP-1 drugs come in the same kind of pen, such as Ozempic and the Mounjaro KwikPen.
How multi-dose pens work
Pens differ in how you set a dose. The Lantus SoloStar label says the pen holds 300 units in 3 mL and dials from 1 to 80 units in steps of 1. The Ozempic pen is a dial-a-dose pen; its 1 mg pen holds 4 mg, which is four 1 mg doses. The Mounjaro KwikPen holds 2.4 mL and gives four fixed weekly doses: you turn the dose knob all the way until it stops.
Each pen also has a time limit once opened. The Lantus label gives 28 days for an in-use SoloStar pen, kept at room temperature. The Ozempic label gives 56 days after first use.
Rules the labels share
- Never share a pen. The Ozempic and Lantus labels both say a pen must never be shared between people, even if the needle is changed, because of the risk of passing on blood-borne infections.
- New needle every time. The Lantus label says reusing needles raises the risk of blocked needles, which can give the wrong dose, and of infection.
- No needle left on. The Ozempic label says to remove the needle after each injection and store the pen without one attached.
- No syringe. The Lantus instructions say not to use a syringe to remove insulin from the pen.
Why it matters when you track doses
A pen holds a known number of doses and has an in-use time limit, so two dates matter: when you opened it and when it will be empty. Logging each dose makes both easy to see. Dose Track can also remind you to reorder before you run out.
Read more on Dose Track: Ozempic guide · Mounjaro guide · Tracking vials and supplies
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.
Can I share an insulin pen if I change the needle?+
No. The Ozempic and Lantus labels both say pens must never be shared between people, even with a new needle, because of the risk of passing on blood-borne infections.
How long does an opened pen last?+
It depends on the product. The Lantus label gives 28 days for an in-use SoloStar pen. The Ozempic label gives 56 days after first use. Check the label for your pen.
Are GLP-1 pens the same as insulin pens?+
They work the same way: a prefilled cartridge, a dose setting and a pen needle. The drug, the dose steps and the in-use time limits differ by product.