How Many Times Do You Prime an Insulin Pen?

October 9, 2025 •

4 min read

According to manufacturer instructions, it is essential to prime an insulin pen before each and every injection to ensure dosing accuracy. Skipping this vital step can lead to a lower or inaccurate dose of insulin, potentially affecting blood sugar management.

Quick Summary

An insulin pen must be primed before each dose to remove air from the needle and cartridge, ensuring the pen functions correctly and delivers the full, accurate amount. Specific pen models may have variations in the priming process.

Key Points

Prime Before Every Injection: Priming is required each time you inject to ensure accuracy and function.
Remove Air Bubbles: Priming expels any air that may have entered the pen cartridge or needle, ensuring a full dose of insulin is administered.
Check for Functionality: The priming process acts as a safety check, confirming that the needle is clear and the pen is working correctly.
Follow Manufacturer's Instructions: The specific priming dose and procedure can vary by pen brand, so always consult the instructions for your pen.
Always Use a New Needle: A new, sterile pen needle should be used for each injection, and the needle should be removed immediately after.
Confirm Insulin Flow: A drop of insulin at the needle tip confirms the pen is primed. If no drop appears after following the recommended steps, you may need to repeat the process or consider replacing the needle or pen.

Why Is Priming an Insulin Pen Necessary?

Priming an insulin pen is a critical safety step that ensures you receive your correct insulin dosage. The process serves two main purposes:

Removes air bubbles: Air can collect in the pen's cartridge and needle during normal use, especially when attaching a new needle. If this air is not expelled, it will be injected instead of insulin, meaning you receive a lower dose than intended.
Confirms proper function: Priming also acts as a safety check to ensure that the pen and needle are working correctly and that the pathway for the insulin is clear. Seeing a drop of insulin at the needle tip confirms the system is functional and ready for your full dose.

The consequences of skipping the priming step

Failing to prime your insulin pen can have significant health implications. Since air in the pen displaces insulin, skipping this step can result in an inconsistent or lower dose. For individuals managing diabetes, this can lead to hyperglycemia (high blood sugar), which can be dangerous, particularly for those who are sensitive to their insulin dosage. Consistent blood sugar control is crucial for preventing short-term and long-term complications of diabetes.

Step-by-Step Priming Procedure

Following a consistent procedure for each injection helps ensure accurate dosing and promotes safe usage.

Gather supplies: Before you begin, gather your insulin pen, a new pen needle, and an alcohol swab.
Prepare the pen: Wash your hands thoroughly. If your insulin is cloudy, like intermediate-acting NPH, roll the pen gently between your palms 10 times and tip it up and down 10 times to mix. Do not shake the pen.
Attach a new needle: Remove the paper tab from a new, sterile pen needle and screw it firmly onto the pen. Remove both the outer and inner needle caps.
Dial the priming dose: Turn the dosage knob to select the priming dose as recommended by the manufacturer.
Remove air bubbles: Hold the pen upright with the needle pointing towards the ceiling. Gently tap the cartridge holder to encourage any air bubbles to rise to the top.
Perform the safety test: With the pen still pointing upward, press the injection button all the way in until the dose counter returns to zero. You should see at least one drop of insulin at the needle's tip.
Repeat if necessary: If no drop appears, repeat the priming steps as directed by the manufacturer. If you repeat the process as recommended and still see no drop, attach a new needle and start over. If it still doesn't work after repeating the manufacturer's suggested steps, discard the pen and use a new one.

Comparison of Priming for Common Insulin Pen Types

While most insulin pens follow a similar priming procedure, there can be slight variations, especially in the priming dose and the specific steps recommended. Always consult the instructions for use included with your specific pen. The following table provides a general overview based on common practice and information from manufacturers.


Feature	Most Common Pens (e.g., KwikPen, FlexPen)	Tresiba FlexTouch	Notes
Priming Units	Follow manufacturer instructions	Follow manufacturer instructions	Always verify with manufacturer instructions for your specific insulin pen.
Priming Action	Typically involves dialing the recommended priming dose, holding upright, and pushing the injection button until the dose counter reaches zero.	Typically involves dialing the recommended priming dose, holding upright, and pressing the green dose button until zero.	Action confirms proper function by expelling air and releasing insulin.
Confirmation	At least one drop of insulin must appear at needle tip.	A drop of insulin must be seen at needle tip.	If no drop appears after repeating the process as recommended, consider replacing the needle or pen.

Proper Needle and Pen Management

Use a new needle every time: Reusing pen needles is strongly discouraged. A used needle is duller, which can cause pain and tissue damage, and increases the risk of infection.
Detach after injection: To prevent air from leaking into the pen and insulin from leaking out, always remove the needle immediately after each injection.
Safe disposal: Dispose of used needles in an FDA-approved sharps container to prevent accidental needle sticks. Never throw loose needles in the trash.

Conclusion

Priming your insulin pen before every single injection is a non-negotiable step for anyone using an insulin pen. It is a simple, quick procedure that ensures accuracy, protects against air being injected, and confirms the pen's proper function. While the general procedure involves dialing the manufacturer-recommended priming units and checking for a drop of insulin, it is crucial to always follow the specific manufacturer instructions for your pen. By making this a consistent part of your routine, you can have confidence in your dosage and contribute to better, more predictable blood sugar control.

Frequently Asked Questions

If you don't prime your insulin pen, you risk injecting air instead of insulin. This can lead to receiving a smaller dose than intended, which can result in elevated blood sugar levels.

The number of units used to prime an insulin pen varies depending on the specific pen model and manufacturer. Always refer to the instructions provided with your pen for the recommended priming dose.

If no drop of insulin appears after priming, repeat the priming step according to the manufacturer's instructions. If a drop still does not appear after the recommended number of attempts, attach a new needle and repeat the process. If it still fails, the pen may be defective and should be discarded.

Yes, you must prime a new insulin pen before its first use. This ensures the pen is ready to deliver accurate doses and confirms there is no trapped air in the cartridge.

Reusing pen needles can cause them to become dull, which can lead to pain, bruising, and damage to injection sites. It also increases the risk of infection and can affect dosing accuracy.

No, you should never store your insulin pen with the needle attached. This can allow air to enter the cartridge and insulin to leak out, compromising the sterility and accuracy of your dose.

Small air bubbles are common and usually not a concern. The priming process is designed to remove these bubbles. If you see a large bubble or are concerned, follow the priming procedure to expel it.

You should always hold the insulin pen with the needle pointing straight up toward the ceiling. This allows any air bubbles to rise to the top of the cartridge, where they can be expelled more easily.