Insulin Pen FAQ's

Insulin Pens: A Guide to Use and FAQs

Welcome to our resource center on injection pens. These devices are a popular and convenient method for administering insulin, peptides and other medications and while their operation is generally straightforward, users often have questions about how to use them effectively. This section provides answers to frequently asked questions, covering topics such as how peptide pens work, how to choose the right one, proper storage, safe disposal, and other essential tips.

Types of Insulin Injection Pens

Insulin pens come in two main forms: disposable prefilled pens and reusable pens that use insulin cartridges. Disposable pens are ready-to-use and available at pharmacies already filled with insulin. Reusable pens, on the other hand, can be refilled either with preloaded cartridges or by manually transferring insulin from a vial into a compatible cartridge.

Many reusable models are classified as smart pens, offering advanced features through app connectivity. These include automatic logging of doses with timestamps, reminder settings, and integration with devices like glucometers or continuous glucose monitors (CGMs).

Smart pens also support broader diabetes management by tracking insulin doses, meals, physical activity, and glucose levels. They help interpret this data and can provide dosing recommendations, making them a valuable tool for personalized care.

What are the parts of an injection pen?

While insulin pens vary in design, they share a common set of essential parts that work together to ensure accurate and safe insulin delivery:

Pen Cap: Shields the insulin and needle when not in use.
Rubber Seal: Forms a secure connection between the pen needle and the pen body.
Insulin Reservoir: Holds the insulin; often includes a transparent section to monitor remaining insulin levels.
Label: Displays the insulin type and expiration date for easy reference.
Dosage Selector: Allows users to dial in the prescribed insulin dose.
Dose Window: Shows the selected number of insulin units.
Injection Button Activates the pen to deliver the insulin dose.

How do I use a pen?

Single-user only: Insulin pens are designed for individual use and should never be shared.
Rotate injection sites: Regularly change injection locations across and within approved areas to maintain healthy skin and avoid tissue damage.
Mixing insulin: For mixed insulin types, gently roll the pen between your palms to blend—never shake.
Priming: Always prime the pen before each injection to clear air bubbles (see detailed instructions in Learning How to Inject).
Injection technique: After pressing the injection button, count to 10 before removing the needle to ensure full dose delivery.
Needle hygiene: Use a new needle for each injection and dispose of it safely after use.

Dosing Accuracy

Double-check the dose: Always confirm the dialed dose before injecting—don’t rely on habit or routine.
Use the correct pen:
- Pens are labeled with the insulin type and reusable pens often have color coding.
- Consider adding custom labels or markings (e.g., permanent marker or rubber band) to distinguish between long-acting and short-acting pens.
- Always verify the label before every injection to avoid mix-ups.

Can Insulin Pens Be Reused?

Insulin pens come in two types: disposable and reusable.

Disposable pens are prefilled with insulin and intended for single-patient use until the insulin runs out or the pen reaches its expiration window—typically 28 to 32 days after opening. These pens require a prescription specifically for the pen format (not a vial).
Reusable pens are designed to be used with replaceable insulin cartridges. To use one, you’ll need two prescriptions: one for the reusable pen itself and another for the insulin cartridges and refills. Once a cartridge is empty or has reached its post-opening lifespan, it should be discarded and replaced.

While the pen body of a reusable pen can be used long-term, needles must be replaced after every injection and properly disposed of.

How do I store my injection pen and how long can I use it before it expires?

Proper storage and awareness of expiration timelines are essential for maintaining insulin effectiveness and avoiding waste.

Storage Guidelines

Unopened insulin pens, cartridges, and vials should be stored in the refrigerator door, where they’re easy to locate and less likely to freeze.
Avoid placing insulin near the back of the fridge, where temperatures may be too cold.
Check expiration dates upon receiving insulin—whether from a pharmacy or by mail—and use supplies in order of expiration to prevent unnecessary waste.
If expired insulin becomes a recurring issue, consider using a logbook to track inventory and expiration dates.

After Opening

Once opened, insulin pens and cartridges can be kept at room temperature, but the duration varies depending on the insulin type.
Most disposable pens and cartridges should be discarded 28 to 32 days after opening, regardless of remaining insulin or peptide.

Can I travel with my injection pen?

Yes, you can—and should—travel with your insulin pens, extra insulin, and related supplies. Here are key precautions to ensure safe and hassle-free travel:

Packing and Storage

Always carry insulin in your carry-on bag, not checked luggage, to avoid exposure to extreme temperatures or pressure changes.
Store insulin between 59°F and 86°F during travel. It can remain unrefrigerated within this range for up to 28 days, according to FDA guidelines.
Use cooling packs or portable refrigeration devices if traveling in hot climates or for extended periods.
Never use insulin that has been frozen, and keep it away from direct sunlight or heat.

Documentation and Security

Bring a copy of your prescriptions for all medications and supplies, especially when flying. This can ease airport security checks and help replace supplies if needed during your trip.
A TSA Disability Notification Card can help streamline the screening process. Try clicking on the link for the official TSA template.
Medications over 3.4 fluid ounces, including insulin, glucagon, juice, and gels for treating hypoglycemia, are exempt from TSA liquid restrictions.
You may request a hand inspection of your diabetes supplies instead of sending them through the X-ray machine. While insulin can tolerate X-rays, this option is available for added peace of mind.

How often should I change my pen needles?

To ensure safe and effective insulin delivery, it's recommended to use a new needle for each injection, or at minimum, replace the needle once per day.

Proper Disposal

Used needles should be placed in a designated sharps container immediately after use.
If a sharps container isn’t available, a clean, rigid household container—such as an empty laundry detergent bottle—can be repurposed, provided it meets local disposal guidelines.
Never discard needles loosely in household trash, as this poses a serious risk of injury to others handling waste.

For specific disposal regulations, check with your local health department or waste management authority to ensure compliance with community safety standards.

Need help troubleshooting common injection pen issues?

If your insulin pen is leaking, malfunctioning, or behaving unexpectedly, here are practical steps to help resolve or prevent common problems:

Preventing Air Bubbles and Malfunctions

Prime the pen before each injection following the manufacturer’s instructions. This clears air from the needle and prevents bubble buildup, which can interfere with dosing.
Never press the plunger without a needle attached, as this can create internal pressure and damage the pen.

Avoiding Leaks

Always remove the needle after each use before storing the pen. Leaving the needle attached can cause insulin to leak and compromise sterility.
When attaching a new needle, hold the pen upright with the tip pointing upward. Tap the side gently to move any air bubbles to the top before priming.

Identifying Physical Damage

Inspect the pen regularly. If you notice cracks, a malfunctioning plunger, or a dose counter that doesn’t move properly, stop using the pen immediately and return it to the pharmacy for a replacement.

Ensuring Full Dose Delivery

After pressing the injection button, count to 10 before removing the needle from the skin. This ensures the full dose is delivered and reduces the chance of leakage.

Can I make injections less painful?

While insulin injections are generally well tolerated, there are several techniques that can help minimize discomfort:

Needle Selection and Use

Use a new needle for each injection to avoid dull tips that can cause pain.
Choose the shortest and thinnest needle available that’s appropriate for your body type. Longer needles may reach muscle tissue, leading to more painful injections and faster insulin absorption than intended.

Injection Technique

Target the fat pad beneath the skin, not the muscle. A shorter needle helps ensure proper placement.
If body fat is minimal, pinch the skin to create a fat pad before injecting.
Inject at a 90-degree angle, or adjust based on needle length and fat pad thickness to ensure accurate delivery.

Site Management

Rotate injection sites regularly to avoid tissue damage and reduce sensitivity.
Use a tracking system or chart to manage site rotation and maintain healthy skin.

How do I know I got the right dose?

To confirm that you've received the full and intended insulin dose, follow these key practices:

Hold the pen in place for a full count of 10 after pressing the injection button. This allows the insulin to fully dispense and helps prevent leakage.
Avoid injecting into areas affected by lipohypertrophy—thickened or lumpy skin caused by repeated injections. These areas can interfere with insulin absorption and lead to inconsistent dosing.
Inject into the subcutaneous fat layer, not the muscle. Proper needle selection and technique help ensure the insulin is delivered into the correct tissue for reliable absorption.

Do All Needles Fit All Insulin Pens?

Most insulin pens are compatible with a range of needle types, but not all needles fit every pen. It’s important to select a needle that matches both the pen model and the user’s individual needs. There is an ISO standard that Nest pens and other reputable models adhere to called ISO 11608. Section 2, ISO 11608-2 lays out the guidelines for double sided pen needles. Any ISO 11608-2 needle will work with this style of insulin pen.

Choosing the right needle length and diameter is essential for proper insulin delivery. The goal is to inject into the subcutaneous fat layer just beneath the skin, avoiding muscle tissue. Using a needle that’s too long or thick may cause discomfort or lead to faster-than-intended insulin absorption.

I Bled, did I get the full dose?

It’s not uncommon for a small drop of blood to appear after an insulin injection. If this happens, gently press the area with clean gauze or a tissue—no need to panic.

As long as the pen was held in place for the full dose and the user counted to 10 before removing the needle, the entire dose was likely delivered.

However, if fluid leaks from the injection site and has the distinct smell of insulin, it may indicate that some of the dose was not absorbed. In that case, contact your healthcare provider to determine whether glucose monitoring or a follow-up dose is needed.

Does it matter what injection site I use?

Insulin is meant to be absorbed into the subcutaneous fat, the layer just beneath the skin. Injecting into muscle can cause faster absorption, which may lead to unpredictable blood sugar levels and more discomfort.
Common injection sites include:
- Abdomen (except within 2 inches of the navel)
- Outer thighs
- Upper arms (back or side)
- Upper buttocks or hips

Each site absorbs insulin at slightly different rates. The abdomen typically offers the most consistent absorption, which is why it's often preferred for rapid-acting insulin.

Best practices:

Rotate injection sites to avoid lipohypertrophy (lumpy or thickened skin from repeated injections in the same spot). This helps maintain healthy tissue and consistent insulin absorption.
Use a site rotation chart or system to keep track of where you've injected recently.
Choose needle length based on body type to ensure you're reaching the fat pad and not muscle. Shorter needles are usually better for comfort and accuracy.

What happens if my insulin freezes or gets too warm?

Frozen Insulin

Do not use insulin that has been frozen, even if it thaws. Freezing can break down the protein structure, making it unreliable or completely ineffective.
If you suspect your insulin has frozen (e.g., stored at the back of the fridge or exposed to freezing temps during travel), discard it and replace it.

Overheated Insulin

Insulin exposed to temperatures above 86°F (30°C) for extended periods may degrade.
Signs of heat damage include cloudiness, clumping, or discoloration—though not all damage is visible.
If insulin has been left in a hot car, near direct sunlight, or close to a heat source, it’s safest to replace it, even if it looks normal.