How To Use Insulin Pen: A Simple Guide For Beginners

So, you’re at the hospital, and someone hands you what looks like the world’s fanciest pen. Insulin pen, they say. Uh… am I supposed to write with this thing or stab myself? Yeah, I’ve seen patients asking me questions like this. Honestly, the thing looks way more intimidating than it actually is.

So here’s the deal. This is your no-BS, straight-up walkthrough for insulin pens. Whether you’re just joining the diabetes club (welcome, the snacks are terrible), helping out your grandma, or your doctor’s making you brush up—whatever. In this post, I'll share everything you need to know about how to use an insulin pen step-by-step.

Main Components of Insulin Pen

Source: Siloam Hospitals

1. Pen Cap – This is the protective cover that keeps your insulin pen safe, clean, and prevents accidental needle pricks.

2. Insulin Reservoir/Cartridge - The small container that contains a specific amount of insulin.

3. Cartridge Holder - Hold the cartridge inside the pen

4. Rubber Seal - A soft barrier that prevents leakage and ensures smooth insulin delivery from the cartridge.

5. Needle Caps—Covers that keep the pen needle clean, safe, and sterile before use.

6. Pen Needle - A fine, short needle that delivers insulin under the skin.

7. Dose Window - A small display on the pen that shows the insulin dose you’ve selected.

8. Dosage Knob - The rotating dial you turn to set the exact amount of insulin prescribed.

9. Injection Button - The button you press to inject the insulin into your body

Types of Insulin Pen

Insulin pens basically come in two types—prefilled and reusable (sometimes people call those cartridge pens, but let’s not get lost in the jargon).

Firstly, prefilled pens. They’re all about convenience. The insulin’s already chilling inside when you open the pen cap. No fiddling around with cartridges or any complicated steps. It’s honestly like those disposable chopsticks you get with takeout: use it, toss it, move on with your life. Super handy if you’re just starting out or you’re not in the mood for an insulin pen DIY project. Just turn to your dose, jab, and when it’s empty? Into the trash it goes. Done and dusted.

Next, reusable pens are a whole different thing. You keep the actual pen and just replace the insulin cartridge when it runs dry. This one’s for the eco-warriors or anyone who doesn’t want to keep cashing out for a new pen every time. It’s less waste, saves you money in the long run, and honestly just feels a bit more grown-up. Sort of like trading in single-use coffee cups for a fancy travel mug—better for the planet, better for your wallet.

Step-by-Step Guide on How to Use an Insulin Pen

1. Wash Your Hands First

Washing your hands keeps your injection uncontaminated and reduces the risk of infection

2. Check the Insulin Pen

Look at the insulin label to make sure you receive the right one. Double-check the expiry date, and if it’s a cloudy insulin, gently shake the cartridge up and down to mix the contents.

3. Attach a New Needle

Remove the pen cap, wipe the rubber seal with an alcohol swab, and screw on a fresh needle. Keep the outer cap for needle removal.

4. Prime the Pen

Before injecting, turn the dial to 2 units and press the button to release a tiny drop of insulin. This removes air bubbles and makes sure your pen is working properly.

You may need to repeat several times before you can observe insulin coming out of the needle.

5. Dial Your Dose

Turn the dosage knob to the exact number of units your doctor prescribed. Make sure it clicks into place so you get the right dose every time.

6. Pick an Injection Site

The most common injection sites are the abdomen, thighs, upper arms, and buttocks. Be sure to rotate your injection spots each day to prevent lumps or irritation, and avoid injecting near scars, wounds, or within about three fingers’ width of your belly button.

7. Inject the Insulin

Pinch the skin lightly, insert the needle at a 90-degree angle, and press the button all the way to zero.

Hold it there for about 10 seconds to ensure the full dose is delivered.

8. Remove the Needle Safely

Pull the needle straight out, then carefully unscrew it with the outer cap and dispose of it in a hard container or detergent bottle

9. Cap and Store Your Pen

Replace the pen cap  and store it properly—unused pens go in the fridge, while opened pens can usually be kept at room temperature (check your insulin instructions).

Common Mistakes Beginners Make 

1. Skipping the priming step

Forgetting to prime the pen means air bubbles may sneak in, and you won’t get the full dose of insulin. Think of priming like warming up before exercise, it only takes a few seconds, but it makes everything work better.

2. Reusing Needles

It might feel convenient to reuse the same needle, but it can cause pain, blocked needles, and even skin infections. Plus, blunt needles hurt more—so always go with a new one each day.

3. Injecting in the Same Spot Over and Over

Not switching injection sites can cause lumps, swelling, or uneven insulin absorption. Rotating injection sites keeps your skin healthy and helps insulin work properly.

4. Storing the pen incorrectly

Leaving insulin pens in a hot car, direct sunlight, or even the freezer can damage the insulin. Proper storage is key—unused pens belong in the fridge, while opened ones can usually stay at room temperature.

How to Travel with an Insulin Pen

Traveling with diabetes doesn’t mean your insulin pen has to stay home in the fridge With a little planning, you can take your insulin on vacation just like your favorite Pokémon plush. Here are three simple travel tips to make sure your insulin pen works as smoothly as your flight.

1. Keep Insulin Cool, Not Frozen

Insulin is sensitive to temperature fluctuations. Store your pens in an insulated travel pouch or a cooler bag to keep them at the right temperature. Avoid placing them directly on ice or in the freezer—frozen insulin spoils and doesn't work properly.

2. Carry Insulin Pens in Your Hand Luggage

Always keep your insulin pens and supplies in your carry-on bag, not checked luggage. Airplane cargo holds can get too hot or too cold, which may damage your insulin. Plus, having it with you means easy access when you need it.

3. Pack Extra Supplies and a Prescription

Bring more needles, cartridges, and pens than you think you’ll need, just in case of delays. Carry a copy of your prescription or a doctor’s note; this makes airport security checks smoother and ensures you can get replacements if needed.

FAQs

1. Do I need to prime my insulin pen every time?

You only need to prime your insulin pen when starting a new pen or inserting a new cartridge. This step clears out air bubbles and ensures your pen delivers the correct dose every time.

2. What are the side effects of insulin pens and how do I manage them?

The most common side effects are mild, such as redness, swelling, or itching at the injection site. These usually go away on their own. Rotating injection spots and using a fresh needle every time can help prevent irritation. 

In some cases, insulin can cause symptoms of low blood sugar like dizziness and palpitations, so always keep a quick snack like glucose tablets or juice handy. If side effects don’t improve, it’s best to talk to your doctor.

3. Does using an insulin pen hurt?

Insulin pen needles are super thin and designed to make injections as pain-free as possible. If you do feel discomfort, try changing injection sites, making sure the needle is new, and relaxing your muscles before injecting. 

With enough practice, many users say it feels like a tiny pinch or nothing at all.

4. How long can I use an insulin pen after opening it?

Once opened, most insulin pens can be used for around 28 days at room temperature, but this can differ depending on the insulin brand. Always check the instructions that come with your pen. A good rule of thumb: jot down the opening date on the pen so you know when it’s time to replace it. Insulin that’s expired or stored incorrectly may not work properly, so don’t take chances.