Definition: Pen priming means pushing a small amount of medicine out through a new needle, into the air, before injecting. It clears air and shows the pen and needle work. Labels call it different things, such as a flow check or safety test, and they disagree on how often to do it.
| Pen | When | If no drop appears |
|---|---|---|
| Ozempic pen | Flow check before the first injection with each new pen only | Repeat up to 6 times, then change the needle and try again |
| Mounjaro or Zepbound KwikPen | Prime before each weekly injection | Repeat up to 2 more times, change the needle, try once more, then call Lilly |
| Lantus SoloStar | Safety test of 2 units before each injection | Repeat up to 3 times, then change the needle; if still nothing, use a new pen |
The KwikPen instructions say priming removes air from the cartridge and makes sure the pen is working. You turn the knob to the prime position, hold the pen with the needle pointing up, and release medicine into the air, not into your body. The Ozempic flow check is also done with the needle pointing up.
The Mounjaro single-dose pen instructions have no priming step.
Skipping a prime the label asks for can mean an incomplete dose if the needle is blocked. Priming more often than the label says uses up medicine the pen was not designed to spare. A prime is not a dose, so do not log it as one. If a pen needed several tries, a note on that dose helps explain a pen that runs out early.
Air bubbles in a pen are expected: the Lantus and Mounjaro instructions both say small bubbles are normal.
Read more on Dose Track: Ozempic guide · Zepbound guide · How to log a dose